2.5 and 1.5 mm Allen key
  • 2.5 and 1.5 mm Allen key

  • Needle-nose pliers

What better way to start a birthday than with the extruder assembly! ;)

John-Robert Yrjölä - Reply

Happy birthday and enjoy your present! :)

Jakub Dolezal -

uh oh, I have the bag labelled E-axis containing the extruder printed parts but see no sign of any of the fixings

i.e bolts, nuts, springs or pulley etc, am I missing a bag? what should the bag be labelled?

Jeff - Reply

Hi Jeff, there should be another bag for chapter 5 with the bolts/nuts/screws. If you can’t find it, please contact our support via live-chat (visit shop.prusa3d.com).

Jakub Dolezal -

Extruder-cover Extruder-body
  • Extruder-cover

  • Extruder-body

  • Attention! Starting August 2017 there is a redesigned P.I.N.D.A. probe holder, remaining parts of Extruder-body are unchanged. See the second picture.

  • Extruder-idler

  • Fan-nozzle (can be in black color, dimensions are the same).

  • Extruder-cable-holder

  • Printed parts are in the bag labeled "E-AXIS".

Also 2 cable holders, used in step 30. Black in my kit.

Francisco Ramos - Reply

Hi Francisco, thank you for your comment. I "refreshed" the photo so it reflects the new items (cable holders).

Jakub Dolezal -

Also on it's pocket it is named E-AXIS

Emil - Reply

Yes, thanks ;)

Jakub Dolezal -

I would update the name of this section to include E-AXIS to ensure that future builders understand which bag to use.

Richie Bishop -

Richie thanks for the suggestion.

Jakub Dolezal -

I have looked in every box and bag that came with the printer, and I unfortunately cannot find the Fan Nozzle part anywhere. Is this not included in the newer i3 mk2s kits? Is it a required part? Is it not in the E-axis bag?

Jason Wright - Reply

Hi Jason, if you can't find it anywhere in the package,

one of our colleagues forgot to include it. I'm sorry about that. You can either print your own from ABS using STL files from here: http://www.prusa3d.com/prusa-i3-printabl... or contact our support at info@prusa3d.com.

Jakub Dolezal -

Thank god I already have another prusa because the Extruder-cover and Fan-nozzle came with pieces broken off...

Justin - Reply

Is the stl model for the new extruder body available somewhere? The version that I can find on the prusa site is the old version. I need to reprint mine because part of it is broken (not an important part - the lower left curved piece.)

Daniel Segel - Reply

Hi Daniel, we are working on it. New design is already on our GitHub and the package with all parts should be renewed soon.

Jakub Dolezal -

Hi, The bag with the printed parts is missing from my kit?

Guy Heylens - Reply

Hi, Received my kit yesterday and was able to get to this step in assembly. Now I notice that the bag with the printed parts is missing?

Guy Heylens - Reply

Hi, also missing the bag of printed extruder parts, Quality inspection is a joke when the signed packing list confirms I should have received all the printed parts!!

Simon Adams - Reply

Guys (@guyheylens, @smadams), I’m sorry about this, please contact our support via livechat or email (info@prusa3d.com) and we will ship you parts immediately.

Jakub Dolezal - Reply

If you're experiencing troubles with getting nut into the top hole, just follow these simple steps. Screw M3 nut a bit on a long screw (M3x40 from 9.SPARE bag works in most cases). Push the screw with the nut into the hole where it is supposed to be.
  • If you're experiencing troubles with getting nut into the top hole, just follow these simple steps.

  • Screw M3 nut a bit on a long screw (M3x40 from 9.SPARE bag works in most cases).

  • Push the screw with the nut into the hole where it is supposed to be.

  • Grab the screw with pliers and gently hammer the nut in place using a wrench.

This "tip" is misleading: Step 6 should include a note that you shouldn't insert a second nut in case you followed this step's images. Also they could me marked as "for illustration only".

Mario Liebisch - Reply

Hi Mario, I'm sorry this step is confusing. It is only a tip, how to insert nut. It is not a regular step.

Jakub Dolezal -

I was mislead by this tip. Just came back from a further step to figure it out.

Fewze - Reply

Hi, Fewze, I'm sorry to mislead you. This step is not part of the assembly, it is only a tip, how to insert nuts. I will redo it.

Jakub Dolezal -

Please have QC inspect for correctly printed extruder covers. I received one (black) with a broken piece of the grid. It did not affect the assembly but for the price I paid for the printer I would like to have all the parts printed correctly. Other than that I am very pleased with the quality of all the parts and the build instructions. Everyone's comments have been very helpful.

Tyrone McCloud - Reply

Hi Tyrone, I'm sorry for sending damaged extruder cover. We are working on improvements every day.

Jakub Dolezal -

I just came back from step 17. My M3 screw basically got stuck with the bolt and I cannot tighten nor loosen the screw. Now I have a screw stuck into the fan and into the extruder cover. I am pretty much stuck and cannot proceed.

Eric C - Reply

Hi Eric, in case you still have issues can you please send pictures and description to info@prusa3d.com? Thanks

Jakub Dolezal -

You should move this "TIP" to step 6. It can be a part of the process.

Eitan Cher - Reply

Hi Eitan, thanks for the suggestion, we will consider the change.

Jakub Dolezal -

Hi, i think it is safer and easier and more accurate to pull the nut in by using screw and washer from the other side. Maybe you could change this tip.

John-Robert Yrjölä - Reply

Hi John, thanks for the suggestion. We are working on a different solution. However, it will take some time to test everything.

Jakub Dolezal -

The fact that this is a [TIP] should be highlighted; I, like a lot of others, are getting confused when we hit Step 6. This really could be presented in a much more logical manner. Perhaps add this "tip" to Step 6. The current format is confusing and really sub-optimal.

Jeffrey Lazar - Reply

Hi Jeffrey, thanks for the feedback. Each chapter is starting with some introduction and explanation. For us, the TIP step should follow, but I will think about some rearrangement.

Jakub Dolezal -

Place the M3 nuts (2 pcs) into the traps on the left side of the extruder body. Slide the M3nS square nuts (4 pcs) into the traps on the right side of the extruder body. Place the nuts as deep as possible.
  • Place the M3 nuts (2 pcs) into the traps on the left side of the extruder body.

  • Slide the M3nS square nuts (4 pcs) into the traps on the right side of the extruder body.

  • Place the nuts as deep as possible.

  • Ensure you have placed all nuts (from both sides of the body).

Somehow I missed installing the M3 nut red arrow second photo. Didn't realize it until attaching extruder later and screw wouldn't tighten. Disassembled back to this point, couldn't find any M3 (regular) nuts in the spares bag, although it said there should be 2 in there. Spares bag did have 2 M3 nylon-insert locknuts, so I used one of those. It would be great if PRUSA could add a few more M3 nuts to the spares. They're very small and easy to drop/lose.

Dave Templeton - Reply

Hi Dave, see my other comment regarding the spare nuts ;)

Jakub Dolezal -

Ha! Continung through the assembly instructions, I just realized what happened to the 2 M3 nuts from the spare bag. They are still on the screws holding on my Y-belt holder.

Dave Templeton - Reply

Hi Dave, you're right those spare M3 nuts are on the Y-carriage. In case you've lost M3 nut, you can also use a square nut from the spare bag to temporarily tighten the Y-belt holder.

Jakub Dolezal -

Adding a note to folks following along to take your time here. I too missed that second nut marked in red, had to backtrack, then didn't set it in deeply enough. Of all the steps, it's the simple ones that get you.

Twerd - Reply

Hi, Twerd, thanks for the feedback, a note added to the manual.

Jakub Dolezal -

I highly recommend gluing the loose nuts into position with hot melt glue. When you get to the final steps of assembly and realize that a nut has fallen out and now you have to take the whole thing apart it is demoralizing.

phil gerskovich - Reply

Hi Phil, nuts should be holding in place by themselves, but thanks for the feedback, we are working on some improvements.

Jakub Dolezal -

A better way to seat the hex nuts than hammering is to insert a screw/washer from the other side, thread the nut onto the screw, then tighten the screw to pull the hex nut into its well until you feel significant resistance. This insures the correct depth and also removes any tilt on the hex nut that might make it difficult to mate with a screw later.

Lane Hauck - Reply

Hi, Lane, thanks for sharing your solution.

Jakub Dolezal -

I wouldn’t recommend this! There’s a chance you will crack the part by overtightening.

jcr -

The square nut that is nearest the top edge of Picture 2 doesn't get secured until Step 27. You'll be cussing when it falls out a dozen times between this step and Step 27. I suggest not putting it in the slot till Step 27 or temporarily stop it from falling out with a piece of tape. You'll be thankful you took heed of this hint!

Richard - Reply

Hi Richard, thanks for the tip ;)

Jakub Dolezal -

Yep, me too. I just added some hot glue like others suggested, that seemed to work fine.

Nicholas Vellenga -

Square nuts on top of picture 2 do not stay in place, the slots have too much play ... adding a small drop of superglue seems to have resolved the problem.

Stuart - Reply

Hi Stuart, thanks for the feedback. I will ask the devs if the slots can be made a bit more narrow.

Jakub Dolezal -

Hi. Old mechanic's trick. Keep the nuts in place with a dab of Vaseline (petroleum jelly) after insertion. Wipe off excess.

Walter Gawronski - Reply

I've temporarily fixated the two top square nuts with the same M3x40 bolt as used for hammering down the nuts.

Mathieu Robroek - Reply

I guess we all had NUT problems. Here goes: The M3 nut (step 4 extruder body) placed in inside hole (first picture) fell into deep hole (step 6 picture 1) of extruder cover after it was closed up (step 7). Not discovered until trying to tighten right screw, Picture 1 step 27, when screw would not tighten or catch nut. Disassembled various parts back to removing extruder cover, 1 and 1/2 fans, etc, Found the nut in the deep hole and tried to stabelize it in its socket but ended up keeping that nut facing up until I could get the assembly back together and get the screw to catch (2 disassemblies later). Hot glue or something sticky would help to keep the nut in place for the next 23 steps.

Merrill Albury - Reply

The part that we are adding the nuts to only has one nut slot on the bottom right (when looking at the same angle as in then first photo above) instead of two. Is this the proper part?

jtfbrowning@gmail.com - Reply

same here... answer?

Davide G -

Hi,

there is an updated version of the PINDA holder. Only one nut is needed.

Jakub Dolezal -

It would work really great except the singular slot isn't wide enough to fit a square nut or tall enough to fit a hex nut. What gives?

Jacob Grafenstein -

Hi Jacob (@grafficmedia), please check there isn't any small particle blocking the slot.

Jakub Dolezal -

This part was printed with such low quality that the nut could not fit far down enough. discovered this in the very last step of this section and had to take everything apart.

This is absolutely crucial as the beginning step, then 23(27-4) steps later everything depends on this one detail. So i feel that you should make sure that the nut tracks are printed okay, and offer a guide for how to secure the nut so that the shaking of the 23 steps does not make it fall out.

oijsadj - Reply

Hi, I'm sorry if there was a printed part with lower quality. In case you can't assemble the printer, please contact our support at info@prusa3d.com

Jakub Dolezal -

The sleeve that holds the Pinta sensor only has one place for the square nut instead as illustrated for two. Was this a design change? Do we have the incorrect part?

Chuck Moore - Reply

Same here. This was already asked on 05.08. PRUSA?

Michael W. -

Well I just finished the assembly and it seems to work fine. I guess it is absolutely irrelevant is the sensor is locked with one or two screws.

Michael W. -

Hi guys, yes there is a design change in the PINDA holder. Only one nut is now needed, the manual will be updated.

Jakub Dolezal -

Thanks for the information on the nuts falling out during assembly, that was good to know before getting started. Since you all gave a heads up and pre-empted future problems by securing them with some flash breaker tape, any tape would work. Just pull the tape as you insert the bolts for each one. Allowed me to not worry about the nuts dropping out.

David Bleakley - Reply

we only have one hole for the square nut!?

Kimberly Hobson - Reply

Hi Kimberly, do you mean the probe holder? Yes, there is an update to the design, see the first step.

Jakub Dolezal -

I only have a single square nut hole as well. is this a change?

Michael Hoyt - Reply

Hi Michael, do you mean the probe holder? Yes, there is an update to the design, see the first step.

Jakub Dolezal -

I strongly recommend that everyone take Walter’s advice above and seat the nuts in the traps using a small amount of petroleum jelly. The nuts have no force holding them in place, so when you try to thread the screw into them, you’re likely to push the nut out of place and/or alignment. This can result in head-scratching and do-overs when the screw won’t catch — please read down to the comments in Step 27 to see what I mean.

Van Albert - Reply

Slide the extruder body on the nozzle as shown in the picture. Push the nozzle all the way down and make sure that cables are on the side as shown in the picture. Be careful with all extruder cables from now on.
  • Slide the extruder body on the nozzle as shown in the picture.

  • Push the nozzle all the way down and make sure that cables are on the side as shown in the picture.

  • Be careful with all extruder cables from now on.

I will like to make a point that from this point forward while building the extruder assembly great care should be taken to not damage the wires on the thermistor and heater cartridge. I kept mine bundled together to prevent them from getting snagged on anything and limit movement.

Paul Betz - Reply

Hi, Paul, good point. Note added to the manual. Thanks.

Jakub Dolezal -

Also go ahead a keep the square nuts out until you need them. The holes are too big and they just fall out while you are building. Especially the left one above the extruder. See the 3rd picture, you will see what I'm talking about. They don't have a nut in the hole in the picture. Just keep it out until you have to mount the extruder to the X-axis.

Paul Betz - Reply

Hi, Paul, thanks for noticing. The nut was there, but deep and not visible. We reshoot this photo. You're right the traps are bigger, but if you move the extruder body carefully, nuts shouldn't fall out.

Jakub Dolezal -

We used a small piece of masking tape to keep the nuts intact and took it off later

Dave DeWitt -

please add a picture of the extruder / cabling from underneath when finished. I had to retrace all the way to here from step 25.

Baziel de Leeuw - Reply

Hi Baziel, thanks for the suggestion, I will reshoot the photos, so it is more clear.

Jakub Dolezal -

I cannot insert the extruder perpendicular. My part looks different as well. Just one square nut. Not sure if I should file the part to make it fit. Came to a point where I lose faith in the building process. Maybe I should stop here and contact the support. Too bad.

Alexander Buschek - Reply

Hi Alexander, please contact our support and send them pictures. Thanks

Jakub Dolezal -

Like Alexander, I'm having problems inserting the extruder perpendicular. I think the printed piece does just not allow it. It does look however, like the extruder should be turned 45 degrees, with cables pointing at roughly 5 o'clock when viewed from first picture perspective. Can anyone please confirm this? This is a brand new printer, so maybe slight change in design here?

Jimmy Larsson - Reply

Hi Jimmy, noted for further tests ;)

Jakub Dolezal -

Same Problem as Jimmy and Alexander here. Is there a solution to this issue? I really dont want to damage the extruder…

Sören Intemann - Reply

Hi Sören and Jimmy (@jimmy_l),

already tested on random Extruder body parts and no issue at all. Can you please send pictures or videos showing, where is the issue? Email is info@prusa3d.com

Thank you

Jakub Dolezal -

Im having the same problem. It seems like there is a approximately 1 mm interference between the plastic extruder body and the heating block, causing the extruder to sit at an angle and bind.

Craig Rogers - Reply

I figured it out. I think its sitting ok now.

Craig Rogers -

White plastic tube (at opposite end from extruder nozzle) did not go through hole. 10 minutes with a needle file solved the problem. Risk of pushing too hard, thereby damaging extruder assembly. This should be changed before shipping the kit.

Walter Banzhaf - Reply

Place the M3 nuts (2 pcs) into the traps of the extruder cover. Top nut needs to be pushed all the way down! (the nut trap has 2 diameters, only last 3 mm have correct diameter for the nut trap).
  • Place the M3 nuts (2 pcs) into the traps of the extruder cover.

  • Top nut needs to be pushed all the way down! (the nut trap has 2 diameters, only last 3 mm have correct diameter for the nut trap).

This top nuts is painful. You should verify if you can temporally mount the fan at this step (see step 17). And secure the bolt with a screw so it stay in place.

Lyrandel - Reply

Confirming that. I did not verify and so I had to come back here when reaching step 17. It *looked* inside but was not.

frederic wagner -

Hi Lyrandel and Frederic, thank you for the feedback, I've asked the designers to improve this printed part, so the nut fits in nicely.

Jakub Dolezal -

Same here; nut is too loose and gets displaced while turning these parts which makes it impossible to tighten the fan later. Had to take it apart at step 17. I tightened the top screw of the fan here and went through the steps again.

Codrin Kruijne -

Yes, either mount the fan once or simply use a screw that will pull the nut in the low diameter trap. Then, remove the screw and the nut should not move.

Thierry Paché - Reply

Your advice of screwing in a screw from the back side to pull the nut in is the best way to accomplish this task. Others should heed this advice. Thanks for the tip.

Paul Genovese -

Hi Thierry, thanks for the tip. We are working on a new design.

Jakub Dolezal -

Excellent tip. I should have followed your guidance, I had to come back and do this step as well.

Robert Klein -

Surprisingly, pulling the nut through did not work for me. I had to take a hammer to it in order to get it fully in there.

Fewze -

Only place one nut (bottom left in the picture), if you placed the example nut from Step 3 above. Don't put two nuts into the same trap or get confused by the example pictures.

Mario Liebisch - Reply

Hi Mario, Step 3 is only a tip. You are right, there must be only 1 nut inside each opening.

Jakub Dolezal -

Thanks Mario - Yes, manual steps implies 2 nuts - following comments saves time as verbal steps can be confusing - as this point is

Albert Alonso -

I think that step 17 must be here, I have to open it again

Emil - Reply

Hi, Emil, you are unable to tighten the fan?

Jakub Dolezal -

I used some hot melt glue to keep all the nuts in place while I assembled things..

phil gerskovich - Reply

Hi Phil, thanks for sharing your approach. We are working on an update to this nut insertion.

Jakub Dolezal -

Top nut also does not stay for me (even when using a screw to pull it into place) ... I had to add a small drop of superglue to hold it in place.

Stuart - Reply

Hi Stuart, thanks for the feedback. Please ensure you can place the screw in, meaning the glue is not blocking anything.

Jakub Dolezal -

The top nut is killing me. My problem was that the second diamter was too tight and I couldn't place the nut all the way up. Hammering did not help, so I pulled the nut using a screw from the back side (with a washer) as suggested by @pacheth. Total disaster, seems like I screwed too much (did not feel like it though), the nut carved a circular hole into the plastic and I cannot unscrew anything.

Yaron Strauch - Reply

The fan is attached to this piece in step 17, however, I recommend partially attaching the fan in this step (step 6). The two nuts you are inserting in this step are the ones which the fan will attach to in step 17. You should attach the fan to this piece by bolting to the deep hard to place nut. This is next to impossible to achieve in step 17 as the nut will come lose as you attempt to push the bolt in (if it hasn't already come lose). Which means you have to disassemble to re-insert the nut. Here are pics of the fan partially attached... http://imgur.com/IzaXPuI http://imgur.com/NrQGabG. At the end of step 7 you can fully attach the fan, as it will obstruct one of the bolts used in step 7.

Neil Martin - Reply

I was expecting quality by buying original prusa, you really have to check before shipping , i had a lot of problems with the top nut

Carlos Talamantes - Reply

I also had a little difficulty with the top nut - I used the head of an M3x40 screw inserted up against the nut and gently hammered it into place using the supplied wrench. Worked a treat.

Angela Pickett - Reply

Hello, the bottom piece off to the side that has to hold a nut is way to small. I’ve tried hammering and carving some plastic out, but nothing seems to be working. Any suggestions?

Ved Kenjale - Reply

Hi Ved, try to place screw from the opposite site and tighten it. If the opening is really too small, please contact our support.

Jakub Dolezal -

M3x18 (1 pc) M3x25 (1 pc) Mind the correct orientation of cables leading from the extruder heater.
  • M3x18 (1 pc)

  • M3x25 (1 pc)

  • Mind the correct orientation of cables leading from the extruder heater.

  • Using the 2.5mm Allen key tighten both screws to mount the extruder cover on the extruder body.

  • Make sure to use the proper length of screws when mounting the extruder cover. Check all nuts are in their places.

  • Tighten until the nozzle stops moving in the extruder, if there's still a gap between the cover and the body it's alright.

  • The M3x18 screw needs to reach just the first square nut. The second square nut is for a different screw used in another step.

To make the M3x25 screw reach the bolt on the other side I had to squeeze the extruder cover and the extruder together with a screwstick, otherwise it was not possible. Be careful not to scratch the smooth side of the extruder as I did.

Claus - Reply

Hi Claus, thanks for the feedback. You should be able to assemble the extruder without any extra tools.

Jakub Dolezal -

I too find too short the M318 screw to reach the second squared nut :(

Alex Tutusaus - Reply

Hi, Alex, everything is fine. The second square nut is for other screw added later.

Jakub Dolezal -

OK i see....the squared nut needs to be free for step27....perhaps worth mentioning "not to worry!" lol :D

Alex Tutusaus - Reply

Yes, exactly ;) I will add a note to the manual.

Jakub Dolezal -

is the M18 supposed t go through both square nuts?

DoubleC - Reply

Hi, DoubleC, no just the first.

Jakub Dolezal -

No. I had to get to step 27 to figure this out.

Lane Hauck - Reply

Hi, Lane, I will adjust this step.

Jakub Dolezal -

At step 24, I am left with M20, although the instruction tells me to use M18. Maybe here M18 means M20.

Kang Sin Choi - Reply

Hi, Kang, the lengths are correct. This M20 screw is the only left?

Jakub Dolezal -

I had a helper push on the hex nut with a long bolt head while I screwed in the 25mm bolt. That helped.

Gordon McDonough - Reply

Before you do this step make sure to check that all the nuts are put in correctly and cant move around (except the square one that don't fit in this are fine) make sure that all the hex nuts are in properly because its a crucial part in the future steps. If not you'll have to take the whole thing apart just for one little nut. If you don't have an extra nut just email the company or got to your local hardware store to try and get one.

Dave DeWitt - Reply

Hi, Dave, you are 100% correct, the nuts must be placed according to the manual. However, we are working on improvements to make these steps easier.

Jakub Dolezal -

Yeah, the slot for the pinda nut fell out without me noticing so I had to work back here from step 21.

David H. Brown -

just a note to all my fellow dummies. make sure you put the hot end all the way back into that slot. my first time around i only put it in the first notch and it resulted in some bad experiences.

Kevin Hart - Reply

Hi Kevin, the hotend must be placed "all the way in", the extruder's body inner side is copying the shape of the hotend body.

Jakub Dolezal -

my cover is two milimeters too large and the screws are not align, should I force ?

Yuuta Jorand - Reply

Hi Yuuta, you shouldn't use any superhuman force. If you need to, then please contact our support at info@prusa3d.com and discuss a replacement. It is better than to cause some irreversible damage to the other parts.

Jakub Dolezal -

My extruder cable came with a zip tie pulled tightly around it the main bundle. This is making it incredibly difficult to cut because I am nervous about cutting a wire.

Please leave some slack when doing this in the future.

Chris Cooke - Reply

Hi Chris, thanks for the feedback. Already sent to the production department.

Jakub Dolezal -

The nozzle seems to be loose after I screwed the cover on. The nozzle and the "box" to which the wires are attached wants to rotate freely. The heat sink area does not rotate with the nozzle... How do I re-tighten it?

Jeremy Martin - Reply

Ok, so I removed the cover and indeed the "box" part was loose. I re-tightened it, made sure the hot end was rotated correctly, and continued. I think there should be a warning note (with a new picture) to check that the "box" with the wires is not loose.

Jeremy Martin - Reply

This section is by far the easiest thing I have ever done in my life

David - Reply

You must be a brain surgeon ?

Brian Knight -

No my friend I am just a standard man armed only with sarcasm. I had so much frustration with this I accidentally all capped my username when signing up just to leave a comment!

David -

No my friend I am just a standard man armed only with sarcasm. I had so much frustration with this I accidentally all capped my username when signing up just to leave a comment!

David -

Tip: Make sure you push the extruder right up into the body so the top flange is hard against the plastic. The nylon filament tube needs to be showing at the top of the extruder body.

I found out when trying to load the filament that it had 'missed' the nylon tube and ended up forcing the extruder out of the extruder body, making it really difficult to correct the situation with all the cables etc now tied down.

Brian Knight - Reply

I managed to get the extruder mispositioned between the printed body and holder parts. I did not notice the problem until I got all the way to preflight check. The xyz calibration worked fine, but the first-layer-calibration failed miserably and I scratched my heat bed, but way at its edge. Scars to show I was stupid at this point. Looking back at the instructions, I cannot see how they could be any clearer. I just did not do the proper visual to confirm it was right before moving on to the next step.

Wayne - Reply

Press the pulley on the motor. The screws must be facing directly against the pad (flat part) on the shaft. If you're experiencing trouble, loose the grub screw a bit.
  • Press the pulley on the motor.

  • The screws must be facing directly against the pad (flat part) on the shaft.

  • If you're experiencing trouble, loose the grub screw a bit.

  • Note the correct orientation (the screw has to be closer to the motor).

  • Don't tighten the pulley at the moment, we have still time for that.

It should be mentioned, that the grub screw (set screw), should be aligned with the flat on the motor shaft and tightened slightly to prevent the pulley from rotating off the flat. This can be done while still allowing the the pulley to be adjusted along the shaft for proper alignment with the filament path.

Scott Miles - Reply

Hi Scott, thanks for the feedback. Note added.

Jakub Dolezal -

Could you please check the tolerance on the pulley? I could not get the pulley to fit without grinding the ID with a rotary tool. The ID read between 4.95mm to 4.97mm and the OD of the shaft was 4.97mm. The area with the smallest ID on the pulley was where the knurling is.

Perry Liu - Reply

Hi Perry, did you manage to fit the pulley on the shaft? If not please contact the support for a replacement at info@prusa3d.com. I will try to get the tolerances from the manufacturer.

Jakub Dolezal -

Jakub, this step took about 30 minutes longer than it should've but yes after grinding down the ID on the pulley I was able to get it to fit.

Perry Liu -

Hello same behavior for me, no way to slide pulley on motor shaft. It will be possible with a hammer....but hard to adjust pulley for next step :) :/

Yoann WYFFELS - Reply

Do NOT hammer in the pulley into the shaft, no matter how tempting it may be (believe me I was tempted). Doing so will very likely damage the motor

Perry Liu -

Hi Yoann, as Perry correctly stated, please do not use excessive force or any inappropriate tool. If you can't slide the pulley on the shaft, please contact our support at info@prusa3d.com.

Jakub Dolezal -

Same problem here, the motor shaft is too big or the pulley.. still figure out the way to fit the pulley in.

Sila Prapinwong - Reply

Same issue here. Received my mk2s 2.03 on July 31 but pulley will not fit over motor. I could force it with a hammer but obviously I won't do that after reading this thread.

Scott W - Reply

I was also given a tight tolerance pulley. With a little lubricant it slides just fine.

Théo Chorques - Reply

Please save someone the trouble that i went through and show a picture of the motor with axis showing that is being used

arthur duarte - Reply

Same tolerance problem. Solved by hand sanding with 400grit and then finishing with 800grit. took a while... this should really be addressed!

Davide G - Reply

Received my kit 11/8/17 and the pulley situation is still the same.Prusa please check your stock and dont ship with these they are not good. Thanks

les - Reply

same problem, but worst, pulley stuck on the shaft...

BlackBeton -

Problem solved : the sanding solution : Roll a métal sanding paper : 7 cm x 2,5cm, in order to have a thin tube corresponding to the Pulley inner diameter, insert it from'one end and let il get through by pulling the other paper edge coming out.

Thick sanding paper (80 in France ) does the job With only one Way from one edge or the pulley to the other.

Cost : 0,59€ for a 25x25cm sanding paper.

BlackBeton - Reply

Same tolerance problem here.

Jeffrey Lazar - Reply

@sila @bigtoga @theo @deddolo @iwik @blackbeton @jdl10011 Guys, thank you very much for you feedback. We are working with our supplier on a solution. If you can't slide the pulley on the shaft, please contact our support at info@prusa3d.com.

Jakub Dolezal - Reply

Add me to the list of people with pulleys out of tolerance. Not sure why shipments would not be halted until this was resolved, you would think shipping pulleys across the world becomes more expensive than stopping shipments until the issue is resolved.

Krutik Bhakta - Reply

Hi Krutik, I'm sorry for the issues. The problem was resolved within an hour, I went straight to the Head of Production. If you can 't press the pulley on the shaft, please contact our support at info@prusa3d.com.

Jakub Dolezal -

Diamater on one end of the pulley was too small so I just wrapped some sandpaper in a cone and spun it a few times. Managed to insert it onto the shaft easily afterward.

Andrei Flores - Reply

Sounds like I too had the tolerance issue mentioned here. I ended up applying a decent amount of force to get the pulley onto the motor shaft. I don't think anything is damaged, but it was a much tighter fit than the other motors.

Steve Oberther - Reply

I received my printer 8/24/17, I think it shipped ~8/19/17. My pulley fits perfectly fine, no issues whatsoever. Whatever you did, Prusa, I think it worked!

Nicholas Vellenga - Reply

Hi Nicholas, thank you for the positive feedback! We checked the pulleys at our warehouse.

Jakub Dolezal -

I used a round metallic fine file to adjust the inner diameter of the pulley in order to slide to the motor shaft

a short video here https://youtu.be/tIDwI--wfY8

Marius Lupu - Reply

Sorry my kit was shipped 8/29 and I am having the issue if the ID of the pulley being too small. I emailed info@prusa3d.com. Is sanding out the pulley advisable or do I need to halt the assembly until a replacement pulley is shipped?

Frank Thomas - Reply

Hi Frank, if there is just slight roughness preventing the assembly, you can try to remove it. However, in case of larger roughnesses I suggest contacting the support. I talked to our team and your email is already in the processing.

Jakub Dolezal -

My kit was shipped on 8/25. Completely jammed up. This is my 3rd Prusa... Quality is getting worse. Not better.

Justin - Reply

Hi Justin, I'm sorry for the issues. I'm reporting all the feedback from the manual to our production team and we are working on improving the quality.

Jakub Dolezal -

Hi I have the same issue. My order was shipped on August 1, 2017. The pulley seems too small.

LP007 - Reply

The pulley was slightly too tight in my kit as well (shipped 28th Aug). I was able to jam it on there using (significant) finger force only though. No hammers or any other barbaric tools needed so it wasn't too bad.

Anton Eliasson - Reply

My issue is that the holding screw in the pulley was fully screwed in, so there's no way I could have just pushed it in from the beginning. Afterwhich, it was pretty hard to slide on the shaft until I moved it a few times.. wonder how much fun this is going to be trying to align it later..

Marauderz - Reply

I had to use a small round metal file (available at Harbor Freight) to file out the inside of the Pulley in order to get it to fit.

My kit shipped on 09/11/2017. I expected higher quality and Quality Control from a high end printer kit like a Prusa.

Dennis Sladek - Reply

Hi Dennis, I'm sorry for the issues. We went through few thousands of pulleys and took out the tight ones. I asked the production manager to add another control process .

Jakub Dolezal -

Same here…spending all night getting this darn pulley on.. Kit received Sep 15

Dave Collea - Reply

Hi Dave, thank you for the feedback. I just talked to the production manager about this.

Jakub Dolezal -

No problems here.

Angela Pickett - Reply

I’m having this extruder pulley issue as well, i can’t even get half the pulley on the shaft before it gets exceedingly stuck. I ordered the printer kit on Sept 11 2017, and it shipped a couple days later. If I contact info@prusa3d.com will they send me a new properly sized pulley? I’m in Canada

Shawn Fuhrer - Reply

Hi Shawn, please contact our support info@prusa3d.com, my colleagues will help you sort this out.

Jakub Dolezal -

Mine is stuck. It’s flush at the edge but won’t go any further down. :(

Monique DeSalvo - Reply

I finally got it off, sanded it and now it’s on there but it still takes some force to move it around. I think it should work though.

Monique DeSalvo -

Kit shipped late October, same problem with ID of hobb too small. :(

Tim - Reply

Hi Tim, thanks for the feedback, if you can't slide it on the shaft, please contact our support info@prusa3d.com.

Jakub Dolezal -

My kit had a similar problem - was able to get it to slide on with a firm push, but only as far as the end of the motor shaft. I was able to get it back off with the same force, so I went with the sandpaper fix. A bit of scrubbing with some rolled up 800-grit, and it now slips on perfectly.

Bill Robitske, Jr. - Reply

Hi Bill, thanks for the feedback.

Jakub Dolezal -

I have the same problem that I was not able to slide pulley on with a firm push. I e-mail info@prusa3d.com but for couple days now. It doesn’t seem that customer support know about this issue.

T. Mek - Reply

Still a problem for me, I took a small file to the inside of the pulley, especially at the end opposite the set screw. That, and a little beeswax on the shaft got it seated without much force.

Tobias Boyd - Reply

In also having the pulley issue on this step.

Chad Frerichs - Reply

M3x30 screws (2 pcs) Don't forget to have the idler in place (the screw has to go through it). Mount the motor on the the extruder body as shown in the picture, double check proper orientation of the motor cables.
  • M3x30 screws (2 pcs)

  • Don't forget to have the idler in place (the screw has to go through it).

  • Mount the motor on the the extruder body as shown in the picture, double check proper orientation of the motor cables.

  • Mind the correct orientation of motor cables.

Probably a good idea to check the small triangle tip with the hole for the filament. In my case it touched/blocked the pulley, since it had some small slope from printing. Just remove it carefully with a small file to ensure the pulley doesn't rub against it.

Mario Liebisch - Reply

Hi Mario, there shouldn't be any part blocking the pulley. I will forward your findings to the quality assurance.

Jakub Dolezal -

The pulley comes really close to the printed part. Is a gap of 1/10 mm ok ?

Luc verlinde - Reply

Hi Luc, there should be a gap so the pulley can rotate freely.

Jakub Dolezal -

Sure looks like it is touching, to me.

DoubleC - Reply

Hi, DoubleC, pulley and the printed part shouldn't be colliding. First, ensure you assembled everything correctly. In case it is still in a collision please contact our support info@prusa3d.com

Jakub Dolezal -

Mine is definitely colliding. Looks like I will need to employ the handy dandy file. If it would be helpful, I can upload or send pictures illustrating this minor problem. I could not figure out how or if picture attachments can be utilized here.

Jeffrey Aschenbrenner - Reply

Hi Jeffrey, please ensure the assembly is correct by going again through the steps. If there is still a collision please send the photos to info@prusa3d.com

Jakub Dolezal -

Hi, maybe you should make a bullet point earlier in the prosess, were we can check if the pulley hits the triangle or not? So we don't have to remove the motor and extruder, if it's necessary to use the file or knife.

Hans Petter Evenrud - Reply

Hi Hans, thanks for the suggestion, however, we will change this printed part, so you don't have to check it all.

Jakub Dolezal -

In my kit (with home-printed plastic parts), there was enough play in mounting the motor, that the gap could be varied from about 1mm to blocking the pulley. So by holding the pulley/triangle assembly up against a light, it is easy to adjust for a small gap while tightening the screws.

jptbrage - Reply

Hi jptbrage, thanks for your feedback. We will adjust the part, so there is no need for any further corrections while assembling.

Jakub Dolezal -

I had to use a razor (utility knife) to carve down part of the triangle section and the white tube coming out of it so they are not touching the pulley. There's not reason the pulley should touch them.

Jeremy Martin - Reply

Same problem, pulley definitely touching the printed part. This pyramid section also has some lumpiness that pinches the feeding tube a tiny bit on the nozzle piece, going to file down both areas to be safe

Scott - Reply

Same issue, any way that I mounted the motor it was touching the printed triangle portion. Filed down the side that was touching and now there's a tiny gap and the motor seems to turn without issue.

Sarkis Einarsson - Reply

@jeremyqmartin @scott @seinarsson Guys, thanks for the feedback, we will make changes in the design.

Jakub Dolezal - Reply

For everyone else still with the old piece or experiencing the problem: Filing down works, but is a lot of work. The printing layers are a good orientation and “pathway”, so I took a really sharp pocket knife and with careful moves I cut just cut down along the layers and remove a very clean part of both the triangle and the transparent tube. Looks clean and now I have a few millimeters distance.

Wolfsblvt - Reply

Tighten the motor screws gently.
  • Tighten the motor screws gently.

Darn, I cracked the extruder body. I over-tightened the lower screw in the photo above. I find it hard to sense how tight I’m making the screws. Hopefully it will work well enough to print a replacement part.

Jackie T - Reply

When I printed the replacement, it was the old style with the two holes on the probe clamp. Do you have the file for the new version with the single hole for the probe clamp? Thanks

Jackie T - Reply

Hi Jackie, see our page with printable parts, it will be in the MK2S zip file: https://www.prusa3d.com/prusa-i3-printab...

Jakub Dolezal -

I made the mistake of putting 3 screws into this piece. The hole was there and it seemed like the thing to do. I had to come back and remove it later, as it was in the way of a later step. Maybe a red circle with a line through it over the third hole ?

Joe O. - Reply

Using the 1.5mm Allen key tighten the pulley. Make sure that the part with smaller diameter is perfectly aligned with the nozzle entrance. Make sure the pulley can rotate freely.
  • Using the 1.5mm Allen key tighten the pulley.

  • Make sure that the part with smaller diameter is perfectly aligned with the nozzle entrance.

  • Make sure the pulley can rotate freely.

  • Use a piece of 1,75 mm filament (from the spool) to align the pulley with the openings for the filament (see the picture).

My filament included was too big, it was 3mm. Also the pulley screw seem defect has the Allen key can't barely tight it without skipping.

E Phenix - Reply

You're supposed to use some of the 1.75mm filament you get for free. the 3mm filament is unly to be used to strengthen the cables. *Don't cut it!*

Mario Liebisch -

Hi E Phenix, you have to use the filament from the included spool, its diameter is 1,75 mm. Regarding the pulley are you sure the screw is facing the flat part of motor shaft?

Jakub Dolezal -

This is an ideal use for the very first part of your 1.75mm filament spool (the bit pulled through the reel to secure it). Just use the pliers and cut it a bit after the last kink, so you're left with nice/straight filament on your spool. Use the cut-off during this step (it should be long enough). Just cut any remaining kinks to get a straight part.

Mario Liebisch - Reply

Mario exactly! +1

Jakub Dolezal -

also having issues with the pulley screw. It will not catch. Threads looks ok, but does not tighten.

Vince - Reply

Pretty sure the hole in the brass pulley is too wide. Screw is loose in the hole and falls out with the skightest tap.

Vince -

Hi Vince, can you please send pictures to the info@prusa3d.com?

Jakub Dolezal -

The triangular piece into which the clear tube from the extruder inserts is too long. with the motor attached, the small brass pully that attaches to the motor rubs too much to turn the motor. Are you expected to file down the triangular block slightly to remove the contact with the brass pulley? moving the pulley doesn't help.

mark young - Reply

same problem here, the motor+pulley can't rotate freely. what am i supposed to do? e-mail you to ask a new part?

Xv Mn -

The pulley supplied was quite tight on the motor axis and i had to gently tap it into place(the screw was loose), would be good to inspect that tolerance before shipping.

John-Robert Yrjölä - Reply

The fit on the pulley and the motor shaft is horribly tight.. It's impossible for me to get the pulley to align perfectly with the cable..

Abhinav Ram - Reply

Same here. Pulley was extremely tight. Needed a tube and a hammer to get it in place.

Alexander Buschek - Reply

+1 on pulley being way too tight. Had to gently tap it on with a hammer even after adding a little oil.

Ryne - Reply

My ptfe tube was too long and had to be shortened to not hit the pulley.

Ryne - Reply

Also my tube was touching the pulley

ALuppens - Reply

@myoung @xvmn @jry @abhi @alexander108 @ryne @eagledown Guys, thanks for the feedback. I'm sorry for the issues. We are working on it.

Jakub Dolezal - Reply

After nearly breaking a nail trying to force the pulley around the shaft.. I realized that the pulley is A HAIR from contacting the ptfe tube holder 'pyramid' Looks like someone smooshed it down already .. but like I said.. it ALMOST got in the way.

Marauderz - Reply

Either I got lucky, or they have tweaked the parts. PTFE tube comes just to the triangle/pyramid tip and there is about 0.5mm clearance to the pulley. Alignment seems good: pushing some filament through makes the pulley spin on the shaft. Nice and smooth until it bottoms out in the hot end.

David H. Brown - Reply

Unfortunately, I have exactly the same problem with a black coloured version. What can I do to make the pulley properly work? It touches both PTFE tube and triangular piece. Can I safely cut the PTFE tube in excess and refine the triangular part? Advice please!

Stefano60 - Reply

Hi Stefano, if you PTFE is hitting the pulley, first please ensure it is sitting tight in the hotend. For the trimming I will provide how-to guide in a day or two. It will be in the English section.

Jakub Dolezal -

A tip for anyone like my who couldn’t get the filament in the tube after the pully: Loosen the screws for the motor again until you can wiggle it. Push it all the way down, hold it that way and tighten the screws again. It seems there is a bit wiggle room for the screws and using that may make the way for the filament more straight.

This way I was able to push the filament bit through and it is only slightly bending around the pully. Which seems like what we want to achieve.

Wolfsblvt - Reply

  • Using the 1.5mm Allen key tighten the pulley. Make sure that the part with smaller diameter is perfectly aligned with the nozzle entrance. Use a piece of filament to align the pulley with the openings for the filament.

  • Video is available in an online (digital) version only.

I am missing the set screw for the pulley. What size is the part so I can try to find a replacement?

Jimmy Spinner - Reply

Hi Jimmy, please contact the support team at info@prusa3d.com

Jakub Dolezal -

Place the M3nS square nuts (2 pcs)  into the traps  of the extruder body. Place the M3nS square nuts (2 pcs)  into the traps  of the extruder body.
  • Place the M3nS square nuts (2 pcs) into the traps of the extruder body.

Bag "5. E-AXIS" contains four M3nS square nuts, which have already been used in step 4 (applies to MK2S version; prior version used only two pcs in step 4). Bag "9. SPARE" contains another two spare pieces which can be used here.

Oliver Dathe - Reply

Hi Oliver, the new package for MK2S contains square 6 nuts. I'm sorry if you received a smaller amount.

Jakub Dolezal -

My Bag did contain 6 square nuts. No problems here. I guess the MK2S has 2 Square Nuts more in the extruder assembly (due to the PINDA probe? We'll see). Maybe you got a bag for the MK2?

Roland Grichnik - Reply

Hi Roland, thank you for confirmation, there should be 6 square nuts included in the bag.

Jakub Dolezal -

I had to shave a bit off as the extruded part was a bit long, the motor bearing hitting the extruded part. I lined up the idler with the spring screws and found my part was a wee bit long and the holes were not true to line up with other holes without lightly reaming out the idler holes to allow a nice loose fit before it is screwed into the motor. I took a picture, Where to upload?

GREGORY - Reply

Hi Gregory, you can start thread with photos here: http://manual.prusa3d.com/Answers

Jakub Dolezal -

5x16sh shaft M5w washer (2 pcs) 625 bearing (1 pc)
  • 5x16sh shaft

  • M5w washer (2 pcs)

  • 625 bearing (1 pc)

  • Place the washers and bearing on the shaft as shown in the picture.

  • Place the shaft with bearing into the idler.

  • Check the shaft is pressed all the way in!

First problems for me in this step.

Getting the bearing into the shaft was difficult with a lot of force to apply on a small surface.

Also, once in place it spins very badly : there is a lot of friction. Is this going to be problematic later on or not ?

frederic wagner - Reply

Hi Frederic, thank you, I will forward your feedback.

Jakub Dolezal -

To answer myself : I removed shaft, washers and bearing and found some plastic defects (protrusion on idler plastic part). I took some time to carefully remove it and put everything back in place. It seems ok now.

frederic wagner - Reply

Hi Frederic, thanks, I send this finding to the guys at QC.

Jakub Dolezal -

This step is a lot easier to do before mounting the extruder motor. Moving this step makes it also easier to not have the square nuts drop out while pushing the shaft in there.

Mario Liebisch - Reply

Hi Mario, thanks, we will look into it.

Jakub Dolezal -

Frederic’s advice above to dissemble the idler from the motor if the shaft is not going in easily, is an excellent advice. Removed the one screw and was able to apply enough comfortable pressure that the shaft popped in really really well.

Michael Hoyt -

I did the same. just removed the top screw which holds the idler, put the idler on the desk, or on top of the two wrenches laid together, so that the bearing can stick through. Then I could easily push it in, check that it’s spinning and screw it back together.

Just make sure that the pully is aligned again. I needed to check how far in I had to put the screw again by looking through the whole to see that the pully matches.

Wolfsblvt -

I too, found that the shaft required A LOT of force to insert into the bearing.

John Mills - Reply

Hi John, sorry for troubles, we will investigate this.

Jakub Dolezal -

Had to get the exacto knife out and shave the side. The washers were just to tight. Now all is good.

Randy H - Reply

Hi Randy, glad to hear you solved it. However, you should be able to assemble this part without any modifications. Thanks for the feedback.

Jakub Dolezal -

The shaft didn't initially fit into the bearing. I had to work it with sandpaper for a few minutes before it could be pressed in.

August N - Reply

Hi August, thanks for you feedback. We will improve this part.

Jakub Dolezal -

Should the bearing spin freely once on the shaft and inserted? Mine barely spins without a bit of force which doesn't seem right

Emilie Corral - Reply

Spins perfectly fine for me. Not much force needed, too. It seems not to be a general issue.

Ralf Hennig -

Hi, Emilie, as Ralf said the bearing should be rotating freely. Isn't there any obstacle (plastic part) preventing it?

Jakub Dolezal -

It would have made more sense to provide this shaft in aluminum or steel, rather than producing it as a 3D printed part. Additionally Jakub, there seem to be a lot of good suggestions, that simply get forwarded to some unknown consensus group for further consideration.

Scott Miles - Reply

Hi Scott, all the suggestions from you are taken seriously and many parts of the printer have been changed accordingly. I'm forwarding these to our developers or guys in production. It just needs time to process them and find better solution.

Jakub Dolezal -

If worse comes to worse, even a fingernail file might be helpful in sanding this part down to tolerance, so that it will function as a shaft for the bearing.

Scott Miles - Reply

Hi, Scott, is your shaft working properly or there are still issues?

Jakub Dolezal -

Tip: To press the 3D printed shaft into the bearing, utilize the two wrenches provided. Place the bearing on top of the smaller opening (13mm) side of one of the wrenches. Utilize the second wrench handle to press the shaft into the bearing (think of a T shape with the wrench forming the top of the T and the bottom of the T is the shaft. The shaft will press through the bearing all the way to the table, giving you a perfectly centered shaft.

Richie Bishop - Reply

Hi Richie, thanks for sharing. Great idea, I would just add to be careful with the amount of pressure, so you won't break the shaft.

Jakub Dolezal -

The plastic shaft is tight in the bearing, and it isn't good for the bearing to put a lot of force on the outer part. I drilled a hole, just larger than the shaft, in a scrap of wood, and put the bearing on that. Then it was easy and safe to push the shaft through. Also, when mounting in the idler, I found the needle nose pliers were perfect for placing force on the shaft ends to pop each one into place.

Mark Leavitt - Reply

While I had trouble pushing the shaft into the bearing, I was able to gently tap it into place using just my table top.

I think it's also worth noting how far pressed the shaft is into the idler. Perhaps a side profile shot would help? I used pliers to pinch the shaft into the idler until it was fully seated. I figured that it wasn't pressed in enough on Step 16.

Perry Liu - Reply

I had a blast pushing the shaft in. It ended working after I tried to put the idler flat on the table, and pressing down on each side of the shaft with the handle of the nose pliers.

Jean-Luc Caron - Reply

Guys, I'm sorry for the issues with the shaft, our team working on improvement. In case you are unable to press the shaft in with a reasonable force, please contact our support at info@prusa3d.com.

Jakub Dolezal - Reply

The bearing was spinning fine after completing step 14 but after completing steps 15 and 16 I can't get it to spin at all. I assumed that was normal. I've now finished assembling the extruder up to step 35 and have it mounted to the X-axis and am worrying that there might be a problem.

Paul Green - Reply

Similar issues - the shaft is actually surpsisingly even throughout measured w calipers, fits into bearing ok except for flared end, but the printed part it pops into is pretty tight. if anyone's having trouble I removed the idler holder part from assembly, then used two very small c clamps and tightened very slowly on each side, went in very smooth without deforming. Be careful not to crush it, kind of pops into place after clearing the first lip.

Scott - Reply

I had to use a lot of force to insert the shaft. I used 2xM10n nuts from the spare bag to support the bearing and a hammer to tap the shaft through. I gradually increased the power of tapping with the hammer until the shaft started moving as I was worried I would warp the bearing. The bearing still worked great for me afterwards.

Neil Martin - Reply

I pass sand paper on the shaft and it went fine. Thank you all for your comment

Rémi Paquet - Reply

Same issue others have mentioned, the bearing doesn't spin once pressed in. There is too much pinching force on the washers, pressing in on the bearing. I took a miniature flat file and filed the sides of the insert where it touches the washers so the inside wall was basically flat. That fixed it.

Ray Ackley - Reply

No problems! 170914

Patrik Olsson - Reply

I had to sand the sides of the idler so that the washer would not exert too much pressure on the sides of the bearing. There was a small lip of plastic at the end of one side of the shaft that I carefully trimmed with an x-acto and sanded thereafter. Worked perfectly thereafter with snug fit of shaft and good rolling of bearing.

Barry Dworkin - Reply

It seems (at least in my case) that the printer used to manufacture the parts had it’s nozzle set too close to the bed, resulting in a “mushroomed” end on the shaft where it sat on the bed. This was a problem with a few other parts in the kit too. A little trimming on the one end and I was able to press the shaft into the holder. If people are having trouble getting the bearing and washers to fit over the shaft, try doing it from the other end.

Ira Schonfeld - Reply

No problems here.

Angela Pickett - Reply

I had no problems with the shaft, but in the kit I received, either the washers are too thick or the cavity where the bearing and washers go into is too narrow. It grips the bearing preventing it from rotating unless a lot of force is exerted. Spins freely with only 1 washer.

Jorg Driesener - Reply

This step should be earlier… before mounting the motor…

Manus van den Berg - Reply

I’m missing the 5x16 shaft. Not in the bag. Is there a substitute that I might find at a hardware store? Or do I need to request another one.

Wayne - Reply

Hi Wayne, please contact our support at info@prusa3d.com, missing shaft should be resolved by us or at least my colleagues will recommend to you appropriate substitution.

Jakub Dolezal -

I used a pair of channel locks (vise grips) to gently press the bearing shaft all the way into the slot, working it in a bit at a time. With the pressure of my hands it only went in half way. The bearing spins freely.

Mattew Farr - Reply

M3x40 screw (2 pcs)
  • M3x40 screw (2 pcs)

  • M3w washer (4 pcs)

  • Extruder spring (2 pcs)

  • Assemble the screws as shown in the picture.

Add Comment

Screw the extruder screws into the extruder body using the 2.5 mm allen key as shown in the picture.
  • Screw the extruder screws into the extruder body using the 2.5 mm allen key as shown in the picture.

  • Length of the springs should be circa 13 mm when tightened.

  • It is alright to tighten the screws with higher force, we need to induce pressure on the idler.

The bearing from step 14 is now in contact with the plastic of the extruder body. At this step it does not spin anymore.

Since I have no idea what his use is I don't know if I should stop here and cut some plastic away or carry on.

frederic wagner - Reply

Hi Frederic, the bearing shouldn't be in contact with plastic part of the extruder. However, after tightening the screws it might be a bit harder to move with the bearing, which is ok because the movement will be achieved by the motor.

Jakub Dolezal -

So, answering myself again (see step 14). After getting a better step 14 I did again this step.

This time I used a small filament piece (not the small sample provided which was 3mm) to give it a try and adjust screws heights.

Everything is moving nicely.

frederic wagner - Reply

Hi Frederic, you should use the 1.75mm filament from the spool for step 14, not the 3mm nylon.

Jakub Dolezal -

A side shot of the assembly would be nice here. It's not clear how much the bearing should spin, freely or tighly. With 13mm spring lenght, my bearing is not spinning at all.

Jasmin Lévesque - Reply

Hi Jasmin after tightening the screws it might be a bit harder to move with the bearing, which is ok because the movement will be achieved by the motor.

Jakub Dolezal -

The bearing is going to press the filament to the gear of the extruder, so it is going to spin when there is filament in the hotend. It can be calibrated later.

Joaquin - Reply

Hi Joaquin, yes exactly thanks ;)

Jakub Dolezal -

I think that my Extruder idler is long and does not fit here, it is not moving

Emil - Reply

Hi Emil, can you take pictures, upload them and share link here? Thanks

Jakub Dolezal -

One note about the square nuts: I had to back off my M3x40 screw three or four times to get it to thread properly. At first it felt like I was cross threading them, but I think that the nuts were just sitting too deep and not aligning properly.

Robert Klein - Reply

Hi Robert, it is important to have the nut and screws aligned properly. I'm glad you solved it.

Jakub Dolezal -

Tightening the screws until the springs compress to 13mm seems ridiculous. I tightened them to 14mm and the idler bearing was already pressing into the into the motor pulley!

Jeremy Martin - Reply

When the filament is inserted, it will push the bearing away, therefore you need to create a reasonable pressure, so the filament is always in contact with the pulley. You can adjust this later on depending on the behaviour during filament loading.

Jakub Dolezal -

Yet another step involving a 3D printed part and yet even more frustration. I just spent an hour trying to get the screw lined up with one of the square nuts, screwing into thin air in the attempt . I finally got it into place and started screwing down and now the square nut is fully rotating with the screw while inside it's little (previously) square-shaped hole. Now the screw with the nut firmly attached can't be screwed all the way in or even be removed to try and find a solution. I am sure this is a fantastic printer but I have had so many frustrating moments failing to put it together that it has left me exasperated. Has anybody had a similar experience? Yet again I am giving up for the night, if I find a solution I will post it here for anyone unlucky enough to run into the same problem.

David - Reply

Hi David, I'm sorry for the issues you have with the assembly. If there are some parts, which won't fit properly, please contact our support at info@prusa3d.com.

Jakub Dolezal -

Even fully seated, pulley easily contacts pyramid shape on filament inlet. Had to disassemble then shave this down a bit, same as the feeder pulley in step 9. Part clearances might have been ok if not for some curling at the corners of this area. Most of the time I've spent in this build section has been cleaning up this one part.

Scott - Reply

I kept a piece of filament in the extruder shaft and pulley while adjusting the spring length (setting them to 13 mm length).

Removed the filament thereafter and bearing does not impact on pulley. Filament can easily be inserted between them with good grip of it between the two parts.

The result is about a 2 mm gap between the pulley and the bearing.

Barry Dworkin - Reply

I had a lot of problems printing with tightening these screws too much. I would seriously recommend a 14mm distance between the printed part and the screw head. Any tighter and the motor can’t pull the filament through, which results in missing layers.

Tobias Hansen - Reply

Hi Tobias, we indicating recommended value, but yours can be slightly different.

Jakub Dolezal -

Typically screw length is not measured including the cap height. I assume the author means 13 mm between the washers (that is not including the screw cap)

Kevin - Reply

Hi Kevin, it is just the length of the compressed springs.

Jakub Dolezal -

Something I noticed was the Idler Screws were THREADING into the Idler, which makes the whole spring screw system non functional. I I filed out the two holes on the idler to allow the idler screws to pass freely. This made the whole Idler mechanism so much more functional and adjustable by the springed idler screws

Anthony Kwon - Reply

Hi Anthony, screws shouldn’t be connected to the idler. After you load the filament the idler must move slightly out. If not, please carefully increase the holes on the idler.

Jakub Dolezal -

I'm not sure if I'm doing it right. My first attemp failed as the filament couldn't fit in the gap as it was too tight when the spring length was 13mm, then i inserted the filament first then screw and the gap of the spring ia approximately 13.2mm

Ryan See - Reply

5015 print fan M3x20 screws (2 pcs)
  • 5015 print fan

  • M3x20 screws (2 pcs)

  • Screw the fan on to the extruder using the 2.5 mm Allen key as shown in the picture.

  • Do not tight fully at this moment, fan should just be secured in place.

  • Front print fan is in the box 2.3.4.5.SUP

For those cannot get the top left screw in -- use a longer screw to push the nut deeper from the other side of the hole (I smash it on the floor to push further).

Kevin Lam - Reply

Be careful. It looks like there is 2 nuts in that shaft. One for the fan, and one in the other side to fix the extruder part on the X-axis (step 26).

I (temporally ?) used a longer screw (M3x25) from spare.

Lyrandel -

Hi Kevin, you have to push the nut at Step 6 all the way down otherwise, you might experience issues similar to yours.

Jakub Dolezal -

Thank you Kevin!!

Abhinav Ram -

The screw M3x25 is too long, but the nut is push in place when mounting extruder on X-Axis, then I replaced the M3x25 with the right M3x20.

Lyrandel - Reply

Hi Lyrandel, thank you for your feedback. It is crucial to press the nuts all the way in the previous steps.

Jakub Dolezal -

If you need to pull the nut down as I did, use an M3x10 + M3nN + M3w direct in to the printed part and tighten until you feel the nut move down. Be careful on the level of force you use as too much will most probably damage the printed part.

Kevin Godwin - Reply

Hi Kevin, thank you for the feedback, we are working on improvement.

Jakub Dolezal -

This worked perfectly. Thanks for the assist!

Wesley DiBona -

That’s the ticket. Thanks!

Tony Williaims -

Didn’t even read the comments right away, but had the same problem. Nut was too far down, couldn’t reach it with the screw when the fan was on. So I took the M3x10 and a M3w from the spare bag and just tightened until I felt it pressed against the printed part. Works perfectly now.

Best tip right here! No need to disassemble the whole thing again.

Wolfsblvt -

I used a smaller screw (M3 x 10 ) with a washer on it like Kevin above and tightened it enough so the M3 x 12 can engage that nut, even if you feel you have it all the way in it can move in assembly or have a bit of foreign matter in there.

Jonathan Wise - Reply

Hi Jonathan, thank you for the comment, we are working on it.

Jakub Dolezal -

Whether you push the nut from step 6 all the way down or not, it doesn't "stay" there when you try and drive the M3x20 through the fan. The nut becomes offset. The back of the nut needs something to press back against to stay in place while the M3x20 is being driven through the fan.

Chad Z. Dawson - Reply

Hi, Chad, when inserting the screw you shouldn't press hard, otherwise, you can push the nut. We will change the design to prevent this. Thanks for the feedback.

Jakub Dolezal -

our solution was to disassemble the cover mount the problematic screw of the fan using counter force on the nut using a long screw. then mount the cover with the fan twisted so we could reach all cover screws. then adjusting the fan back to its place so we could mount the second screw.

yaron ronen - Reply

Hi, Yaron, thanks for the feedback. We are working on it.

Jakub Dolezal -

This one screw took over an hour and I used a combination of yaron's disassembly, pounding th nut in place a bit (I think my earlier attempts couldn't reach the nut - debris?), finally getting the one nut and fan on the disassembled mount, pivoting the fan to reach the other holes in order to reassemble. Yuk. Probably over an hour (maybe way more) on one fan screw. Everything else has been great so far but this one was a bummer

Jeff Tapia - Reply

Hi Jeff, sorry for the troubles with your assembly.

Jakub Dolezal -

Again I was shorted a screw of one size and given an extra screw of a different size. Missing a 20mm and have an extra 18mm.

Paul Betz - Reply

Hi, Paul, I'm sorry for troubles. You can use one from the spare bag.

Jakub Dolezal -

this is the worst step. the screw won't bite, the nut appears seated.....tempted to use a spare 25 mm screw....

DoubleC - Reply

Hi, DoubleC, please use the lengths described in the manual. If you can't reach the nut, try our insertion tip again.

Jakub Dolezal -

My method (quick and easy!)

Took an M3x30 and screwed it through the fan instead of the M3x20 . When I felt it was tight, I removed it slowly and gently without pushing it down. When the M3x30 was out, a quick peek into the hole revealed that the nut was pulled towards the fan.

Now I can screw the M3x20 again very easily, just be careful not to push it too much, so that it will catch the nut instead of pushing it out again.

Using this method it took me 2 minutes to assemble this screw.

Udi Finkelstein - Reply

Hi, Udi, interesting approach. Thanks for sharing.

Jakub Dolezal -

Don't try this. I did this and stripped the printed part. Now I can't take my M3x30mm out and it's stuck on the fan and the printed part. :/

Eric C -

I used the m3x40 to push from the other side (not twist and insert, just leave it against it and push) incase it didn't push all the way in the previous step. thank god that hole was there.

Simon Grigorian - Reply

Hi, Simon, the nut wasn't holding in place or you insert the screw from other side, just to be sure?

Jakub Dolezal -

Now would be the appropriate time to install that nut, noted for installation back in Step 6.

Scott Miles - Reply

Hi Scott, I suggest to stick with the manual.

Jakub Dolezal -

I didn't have any problem putting the screws in place. But I managed to crack one of the fan screw holes. Not a big deal as the crack is small. It was my bad as I overtightened the screw but on the other hand it doesn't take much to do so. Since the fan holes are quite big compare the the screw heads. I ended up adding the two small washers from the spare pack.

Premik - Reply

Hi, Premik, you have to be careful while tightening plastic part with "steel" screw, the amount of pressure you can introduce can easily break the plastic part.

Jakub Dolezal -

The bearings on my fan pretty much failed after 20 minutes. The noise is just amazingly loud!

Has anyone else experienced that?

Andrea Lini - Reply

Hi, Andrea, check there isn't some part of the fan cable inside or piece of plastic. If the fan is "obstacle-free", please contact our support for a replacement at info@prusa3d.com

Jakub Dolezal -

Just for clarification: it a rattling sound.

Andrea Lini - Reply

The nut casing is so loose that it was not possible to make the nut stick. I was able to screw the M3x20 in place by:

1) use the 1.5mm tool through the opposite hole to orient the nut

2) screw a M3x40 through the opposite hole through both nuts. The nut is now operatable, but it is in the wrong position on the threads. We fix that by...

3) screw a M3x25 though the fan & hole until it collides with the M3x40

4) unscrew the M3x40 at the same time as you continue screwing the M3x25, it will catch the nut and you will be able to pull out the M3x40.

5) tighten the M3x25. The nut is now resting where it should be, but we need to switch to a shorter screw. We do that by...

6) screw in the M3x40 again through the opposite hole until it collides with the M3x25.

7) unscrew the M3x25 and at the same time screw in the M3x40.

8) screw in the M3x20 and unscrew the M3x40 as the M3x20 collides with it and at the same time it catches the nut.

9) profit!

VK Arponen - Reply

Thank you so much for your solution! This was the only way that I could work out how to do it. This step really needs to be changed to be easier as it took me about 45 mins in total to screw in one screw.

James -

The fan screw is too short. I can't even connect it just to the part of the case not attached.

Kiel H McGettigan - Reply

I ended up having to use a longer m3 25 screw to get this to work

Kiel H McGettigan -

I installed the fan on the Extruder-cover before putting the Extruder-cover together with the Extruder-body (i.e. before step 7) I used only one screw at that point, (the one with the difficult nut). I used an M3x25 screw from the spares bag instead of the prescribed one. At step 17, I just had to add the second screw. Worked fine.

liza - Reply

It was a !&&* trying to catch the nut with the screw after the assembly. I dismantled the whole extruder until I could reach to the nut, which had enough space in there to turn sideways. I tried to seat it as flat as possible in the hole, then placed another bolt with the head in the hole, to cover the nut as thoroughly, them wacked it with a hammer to be sure the nut is completely in and verified that it stays still no matter how I shaked the extruder. Then mounted the fan on that hole only and put the extruder back together (the other fan mount would cover another hole if used). If I were to give a piece of advice it would be to force the nut in that hole either by using a bolt and a washer and pull the nut until it stays there no matter how you shake the plastic part or use the head of a bolt and hit that bolt on the open end with a hammer (I just felt it went completely in). My 2c.

Florian Ford - Reply

Hi Florian, I'm sorry for the troubles you had.

Jakub Dolezal -

This is RETARTED! This stupid nut should be inserted from the SIDE like the square nuts are, not from an in-line nut trap where the screw is gonna push it back out of the deep trap. This is an OBVIOUS solution and needs to be implemented IMMEDIATELY.

Jeremy Martin - Reply

That being said, Florian's worked for me. Remove the extruder cover and used a long bolt, the 30 or 40mm to HAMMER in the nut from step 6. Use the head of the bolt, stick it into the nut trap and HAMMER that sucker in. You will feel it begin to SINK into the plastic, deeper than you though it needed to go. Then, put the fan screw on BEFORE you replace the extruder cover.

Jeremy Martin - Reply

Be careful when tightening bolts, my fan will not start without helping by rotating it with my hand, then it spins ok. I guess that even very decent amount of force can damage fan.

Mika Laurila - Reply

The 3D printed piece holding the nut for the top left screw wasn’t deep enough. We had to heat the nut with a lighter and push it a little into the shaft.

Théo Chorques - Reply

To me this was the most troublesome step so far. I've tried all the tricks that is mentioned in the comments. But i really think that it is impossible for the 20mm screw to reach. Might be some be some plastic in the nut track that I'm not seeing, but can't remove it anyways or pull the nut close to the fan side.

Luckily the 25mm spare solved it for me and I'm able to progress.

oijsadj - Reply

I ended up having to pull out the screws from step 10 so I could get at that top left nut. I used one of the longer screws to push the nut in and then popped the screw on top with a rubber mallet. I unscrewed the screw carefully and mounted the fan before putting back the part from step 10. If you have a spare 25mm, that will do it, too.

Juan Ruiz - Reply

Yep. This step is a bummer. One caveat: it's easy to mistake an 18mm M3 for the necessary 20mm M3. It's still a bit of a puzzle to even get the 20mm to catch, but it can be done. I utilized the trick where I screwed in a 40mm from the reverse side and hammered the bolt in a bit deeper, which allowed the 20mm to catch. PRUSA could improve upon this step.

Jeffrey Lazar - Reply

Hi Jeffrey, thanks for the feedback. We are constantly improving the printer. Regarding the proper size of the bolt, please use the labels on the bags, where bolts are printed in scale 1:1 for direct comparison.

Jakub Dolezal -

Pretty obvious there is room for improvement here. People are following instructions (making sure the nut is all the way down) and are still having to improvise for this step. You've asked us to be careful with the parts, this step make that tough to do if we're having to hammer/put enough pressure on the nut to have a screw catch. People will also try to put too much pressure on the fan in order to get the screw to catch. Please fix this step either with better tolerance with the 3d part, changing the design of how the nut is placed, or simply using a different sized screw. Thanks.

Krutik Bhakta - Reply

Ok. It’s either a poor design, or the part needs greater print accuracy. Regardless, I used a M3x40 and inserted it in the opposite end pushing the nut to the top. Then from the fan i used a spare M3x25 and used opposing forces until the left fan nut caught and threaded. Not elegant, but it worked. This DEFINITELY needs IMPROVEMENT!

scott chavez - Reply

Thanks Scott, we are on it.

Jakub Dolezal -

No problems here.

Angela Pickett - Reply

Be careful trying to push the nut deeper into the hole. I snapped the arm off trying to get the nut to go deeper into the hole so that the M3x20 would reach the nut.

Steve Gevers - Reply

I struggled for about 15 minutes before I gave up and used a 25mm screw from the spare parts.

Kristian - Reply

I also had to use a long bolt from the other side (M3 x 30 in my case) to push the lower nut closer to the fan mounting bolt to hold it there until the threads caught.

Tobias Boyd - Reply

I think I had every problem mentioned above and maybe a couple not mentioned with those two bolts in the fan. That nut at the bottom of that long shaft kept moving around and other nuts kept falling out of their slots. I finally used some glue and a longer bolt to set it in place, then replaced the longer bolt with the correct size. Please add my vote to those calling for a design change. Perhaps that shaft could be shorter and a longer bolt used? Thanks.

jimbo.dickinson@gmail.com - Reply

Fan nozzle M3x20 screw (1 pc)
  • Fan nozzle

  • M3x20 screw (1 pc)

  • Tighten the fan nozzle using the 2.5 mm Allen key. Gently tighten screws holding up the fan in place.

  • DON'T tighten the screws too hard, all parts are made of plastic and you can break them.

  • Double check that the fan can rotate freely.

Fitting the fan nozzle was quite difficult. The fan nozzle wobbles around and fits poorly on top of fitting a screw into the untreaded 3Dprinted plastic hole. This is far below the high quality standard of all the other items, so I would suggest to redesign the nozzle fan mounting.

Claus - Reply

Hi, Claus, thanks for the feedback, I already forwarded this to the design department.

Jakub Dolezal -

the fan nozzle is 1.5 mm too short to adequately mount. I can force it but it no longer is properly seated and leans at an unnatural angle.

DoubleC - Reply

I've filed fown the edges so it has a better fit but I wonder how long this piece eill last once it experiences its branding - "HOT!"

DoubleC - Reply

Hi, DoubleC, try to slightly release screw holding the Print Fan, reseat both parts (fan + nozzle) and tighten it again. Let me know if it helped.

Jakub Dolezal -

Just curious, this is the first screw that I noticed which is screwed directly into the plastic without a nut on the other side. Why haven't you put a nut there too?

Udi Finkelstein - Reply

Hi, Udi, nuts are always used to tighten in place heavy or loaded part. This fan nozzle part is very light itself and not loaded, I assume this is why there is no nut.

Jakub Dolezal -

This is one case where pre-threading the hole using the screw, for at least a few threads, will help. Then take out the screw and insert it through the nozzle body. If you keep the nozzle slightly raised from the extruder body, you can see the screw tip and guide it into the hole. Thread it in a few turns, then press the nozzle down into position. It helps if you kept the fan screws quite loose as the nozzle has to engage with the fan and the extruder body. Now finish tightening the screws and voila!

Mark Leavitt - Reply

On mine, the hole in the plastic has too large a diameter to grip an M3 screw - so the screw is effectively only acting as a peg. Will see how it performs - may have to replace with a longer screw and a nut.

Jo Wilson - Reply

Survived a few months, but now so wobbly it has come off a couple of times mid-print, jamming the extruder motion and causing layer shifts and spaghetti. A wee dot of superglue holding it for now, but will probably replace with a longer screw and a nut.

Jo Wilson -

I happened to have just bought a cheap set of metric taps and dies which I'll be using for my models anyway, I tapped the hole out to M3x.06

Walter Gawronski - Reply

Above the HOT-text is a approx. 1 mm gap between the fan and the fan nozzle. The cooling air could go up there instead of fully cooling the nozzle. Is that okay or a problem?

Nadine Buitkamp - Reply

Hi Nadine, there can be a small gap. It is important to ensure, the majority of cold air goes downwards to cool the printed object.

Jakub Dolezal -

I cracked a bit the fan's mounting holes because those holes are quite big and the head of the screw is not that big. I used washers from spare bag and it is fine now. Might be better to add washers to mount the fan.

Grégoire Saunier - Reply

I just want to say that at this point I could find an M3x20 but I still have all my M3x18.. hope that doesn't come back and bite me..

Marauderz - Reply

Hi Marauderz, follow the manual and you will be fine. Also, there is a bag with spare screws, just in case.

Jakub Dolezal -

I had read somewhere that having a 3mm tap on hand would help. It did. Maybe the hole could be tapped at the factory?

David H. Brown - Reply

Hi David, most of the openings are tapped in the factory to ensure easy assembly, I will check whether this one is as well.

Jakub Dolezal -

No problems here, I pre-threaded the hole slightly using the screw

Angela Pickett - Reply

Prepare the P.I.N.D.A. probe (autocalibration) by removing both of the nuts (if included in delivery)
  • Prepare the P.I.N.D.A. probe (autocalibration) by removing both of the nuts (if included in delivery)

  • P.I.N.D.A. probe is in the 2.3.4.5.SUP box.

since MK2S there is no longer a nut on the probe. If not included in the delivery, you are ready with this step.

Heiko Schultz - Reply

Hi Heiko, thanks for the comment.

Jakub Dolezal -

Just wasted 10 minutes looking for 2 nuts - so how come this is not clear in the main guide - frusrating!

Albert Alonso -

Please add a reminder, like in other steps, that the P.I.N.D.A sensor is in the 2.3.4.5.SUP box.

Udi Finkelstein - Reply

Hi, Udi, thanks note added.

Jakub Dolezal -

Pass the P.I.N.D.A. probe through the mount. Guide both cables through a cable clip on the extruder body as shown in the picture. Exact position of the P.I.N.D.A. probe will be adjusted later (in Chapter 9, Preflight check), so there is no need to adjust or tighten fully at this point.
  • Pass the P.I.N.D.A. probe through the mount.

  • Guide both cables through a cable clip on the extruder body as shown in the picture.

  • Exact position of the P.I.N.D.A. probe will be adjusted later (in Chapter 9, Preflight check), so there is no need to adjust or tighten fully at this point.

  • The best position for mounting at this point is to align the last thread of the probe with the end of the mount

  • Note the loop on the cable from the probe, it's necessary to apply it correctly!

There is a typo in "Guide both cables trough a cable clip on the extruder body as shown in the picture.". "trough" should be "through". :)

John Wells - Reply

Hi John, thanks corrected ;)

Jakub Dolezal -

If it is difficult to pass the probe through, you can gently lift the top of the printed part to give the probe more clearance.

DoubleC - Reply

Hi, DoubleC, you can slightly lift the printed part by included screwdriver, BUT BE VERY CAREFUL! You can break the holder.

Jakub Dolezal -

Yes, be careful !! I broke mine. Getting anxious to complete the kit, not being careful enough.

Joe O. -

It is better to pass the wire first through the gap on the side and then screw the probe back into the body, instead of trying hard to push the probe.

Jack Xu - Reply

I agree with Jack -- the cable hook interferes with insertion of the PINDA probe from the top. At the other end of the PINDA cable, there's a section where the jacket is absent for about 20 mm. This is long enough to slide sideways into the slot in the PINDA clamp. I did hold the slot open with the small screwdriver while inserting the wires sideways. Now just gently pull the cable up as you move the PINDA into place from the bottom. Before you being inserting the PINDA body though, create that cable loop as shown as it won't be possible after the PINDA is in place.

Mark Leavitt - Reply

I have removed the heat cartridge and therm as it looks like it will get damaged.Put it back later .

Phillip Kearney - Reply

On my Prusa this is a big problem, I am not able to adjust the probe without removing both screws and lift the printed part with a screwdriver quite strong. I feels like the thread on the probe does interfere with the printed part. And i'm also not able to fine adjust the probe, its' only possible in big steps. I would suggest (for other kit builder) to clean the hole for the probe before mounting.

Daniel B - Reply

Hi Daniel, if the issues still persist please contact our support at info@prusa3d.com. Thanks

Jakub Dolezal -

I also encountered this problem and it seems that the inside of the hole is rather rough so the threads of the PINDA probe get hung up on every little irregularity. It may not be Kosher but I smoothed the I.D. by gently running a 5/16" twist drill by hand through the hole and cleaned off all the burrs. Smooth Sailing!

Stu Rasmussen - Reply

Hi Stu, important is to leave some thread on the printed part, so the PINDA probe won't be sliding downwards.

Jakub Dolezal -

Annoying. I had to file down an irregularity inside the printed portion so the PINDA would slide in. This file set has been the most used item I purchased prior to beginning the build.

Angela Pickett - Reply

Having assembled four of these consecutively, I would report that this is a consistent pain point. My four 3D printed extruder holder parts simply did not want to fit the PINDA probe through, even with considerable pushing from behind, without prying open the slot with a screwdrive. I broke two of them and had to superglue back together. Certainly, this could be designed with a LITTLE bit more tolerance? There is a tightening screw, after all.

Jobosh - Reply

Hi Jobosh, the PINDA probe holder was remodelled according to the feedback from users. Are you sure, you've printed the latest version available?

Jakub Dolezal -

I also thought it was threaded until I read the comments. Of course, once you have the probe inserted and the loop in place you can’t twist it anymore. I took it out and inserted it in the opposite direction and scrubbed it in and out several times. Then I installed it the proper way and it worked as intended.

John Heaney - Reply

Real difficult to put probe in mount. My mount broke. I have glued it back together, then had use a Dremel tool to enlarge the opening. Probe in finally. It fits, but not too loose.

Joe O. - Reply

This is so frustrating. I couldn’t push the prope through. Had to insert it a bit at an angle because the cable holder was block it. Couldn’t push it in fully. I feel like the threaded outside prevents it from really going through.

Had to use the plier to grab the end of the probe and a lot of force to get it in, then had to pull from the top end and just screw it as if the outside was really threaded to something. The plier ruined the “prusa3d.com P.I.N.D.A. probe” label now :(

Wolfsblvt - Reply

Secure the P.I.N.D.A. probe with M3x10 screws Note the loop on the cable from the probe, it's necessary to apply it correctly! New design of the holder requires only one screw M3x10. See the last picture.
  • Secure the P.I.N.D.A. probe with M3x10 screws

  • Note the loop on the cable from the probe, it's necessary to apply it correctly!

  • New design of the holder requires only one screw M3x10. See the last picture.

Nice feature apparently, but no longer the possibility to protect the PINDA sensor like for MK2. May be a slight modification of the extruder body in order to protect it from the start?

Thierry Paché - Reply

Hi Thierry, I discussed this with developers and they will have a look into it ;)

Jakub Dolezal -

We found it very difficult to make this work with M3 10 mm screws; they just wouldn't engage the square nuts once the sensor was in place. We ended up using M3 12 mm and they seem to work okay.

Anne - Reply

Hi Anne, please follow the manual, M3x10 screws are long enough.

Jakub Dolezal -

M10 worked with a little pressure to close the gap between the upper and lower pieces.

DoubleC - Reply

Hi, DoubleC, thanks for confirming.

Jakub Dolezal -

Tightened the screws and closed the gap to 0, PINDA is still loose in the holder. Now what ? Wrap it with tape ?

Dave Cook - Reply

Hi Dave, please ensure both screws reached the nuts. If it is still not holding in place, please send pictures and description to info@prusa3d.com

Jakub Dolezal -

Screws are almost too short or 3D printed part may need to be revised to move nuts closer. I was able to get the screws to just start to engage nuts by applying pressure.

Stuart - Reply

Sure, M3x10 are too short, i used spare M3x12.

Thomas - Reply

I did too, I can see difficulty in the adjustment phase if you need to apply pressure to the screw and hold the sensor in place at the same time, also it's a risk of messing the treads when it's barely engaging.

John-Robert Yrjölä -

M3x10s wouldn't engage the square nuts. I gently, GENTLY, compressed the P.I.N.D.A. mount with the provided needle nose pliers.

Ed Lingo - Reply

screws are tight and will close the gap to zero. If it is still loose then it may be your printed part did not maintain the light threads in the shaft hole or it shrank giving it a bit of sick. In any case I thought it wasn't going to tighten until the last few turns.

Kevin Smith - Reply

Guys thank you for the feedback, screws M3x10 should be enough and I've tested this several times. Please check the probe is sitting inside the holder properly.

Jakub Dolezal - Reply

I think that because of slight variance in the print qualities the 10 mm screws are unnecessarily short 12 mm just works better, at least in my case did.

John-Robert Yrjölä -

I only have one place to insert the screw.

Chuck Moore - Reply

me too.......

Chad S Richardson -

I seem to have an updated version, only one M3x10 leaving a spare M3x10 bolt and square nut.

John - Reply

Same here. Have updated version. No issues.

Barry Dworkin -

I had to use the pliers to squeeze the gap closed enough to get the nut to engage. It worked, but really doesn’t feel ideal.

Bill Robitske, Jr. - Reply

M3x18 screws (4 pcs) Note the correct orientation of the fan. The sticker has to face towards the nozzle! Guide cables from the extruder motor via slot in the extruder body, put the fan in place.
  • M3x18 screws (4 pcs)

  • Note the correct orientation of the fan. The sticker has to face towards the nozzle!

  • Guide cables from the extruder motor via slot in the extruder body, put the fan in place.

  • Using M3x18 screws mount the fan to the extruder body using the 2.5mm allen key as shown in the picture.

  • Tighten fan screws gently using the 2.5 mm Allen key.

  • The Left hotend fan is in the box 2.3.4.5.SUP

Threading the screws through the fan directly into the plastic took a bit more muscle than I expected.

Robert Klein - Reply

Hi Robert, it shouldn't be hard to thread the screw. We will investigate this.

Jakub Dolezal -

Guys, I used a torque gun to make some pilot threads and also screw in the fastener later.. It works well, but should be used with caution

Abhinav Ram -

Same with mine.

Monique DeSalvo -

Recommend starting threads with the M3 fastener before installing fan!

Chris Renner - Reply

Hi, Chris, thanks for the suggestion. However, you should be able to mount the fan without directly without any adjustments.

Jakub Dolezal -

Unfortunately, my printed housing had two holes that were tight and the other two were two large so the screws had nothing to fix to. These are black printed parts. Will fill with epoxy and drill to correct size.

Gary Johnson - Reply

Hi Gary, thanks for the feedback. Can you send a picture to info@prusa3d.com?

Jakub Dolezal -

My printed housing was the same: two (next to the print fan) tight and other two too loose.

Tony Hansen - Reply

Hi Tony, thanks for the comment. Can you also send pictures to info@prusa3d.com? Thanks

Jakub Dolezal -

Mine had the same issue as the above comments, black printed parts with the top and bottom holes on the left hand side being too big. I have just omitted these screws for now as the fan is very secure using the two holes on the right hand side.

Zack Holmes - Reply

Hi, Zack, thank you for the feedback.

Jakub Dolezal -

Same issue with mine. (all black version) Solved it by putting a piece of wooden toothpick in the two holes, then i could gently tighten the screws. But this needs a fix.

Kenneth Bareuther - Reply

Hi, Kenneth, thank you for the feedback. If you need replacement, please contact info@prusa3d.com

Jakub Dolezal -

I had the same issues as the others. Two holes next to print fan were okay, the two on the other side were too loose. Mine are orange printed parts.

Paul Betz - Reply

Hi, Paul, thank you for the feedback. If you need replacement, please contact info@prusa3d.com

Jakub Dolezal -

"Hi Chris, thanks for the tip. This part is designed to work without the M3 fastener."

Jakub, in the English language a fastener is a generic term that can refer to either a nut or a screw. Certainly you aren't suggesting that the fan can be mounted without the screws. Again, this is another instance when someone truly fluent in English, would be helpful.

Scott Miles - Reply

Hi, Scott, thanks for the comment. I've corrected my reply.

Jakub Dolezal -

What Chris was suggesting was that starting the screws and piloting threads. prior to mounting the fan could be helpful.

Scott Miles - Reply

"Left fan is in the box 2.3.4.5.SUP" . Is there a Right fan? I assume you meant the remaining fan. Very confusing language!

Scott Miles - Reply

Hi, Scott, yes this is the second (and remaining) fan in the box. Please, place it according to the description.

Jakub Dolezal -

One hole was too small to catch a thread after a few minutes of persistent effort so I'm just mounting with three screws

Jules - Reply

We have orange parts. All of the holes were OK but the screws were very hard to get started and screwing in required a lot of torque. When doing this step you really need to pay attention to where the wires are. Also because the screws need so much torque to get them home you need to be sure while getting leverage you do not break the wires off of the extruder

Dave DeWitt - Reply

Hi Dave, yes it is necessary to be careful during the assembly.

Jakub Dolezal -

Way too much force required raising lots of possibilities for damage. I don't think it's a good design practice to use long, fine threaded machine screws to self-tap into plastic, especially when the hole sizes can't be tightly controlled. Please consider a design change to use thread forming screws for plastic (Plastite and other brands) in these locations.

Mark Leavitt - Reply

Hi Mark, thanks for the suggestion. I will push your idea forward.

Jakub Dolezal -

One of the holes wasn't perfectly positioned so I could only put 3 in... seems solid but should I be worried?

Jean-Luc Caron - Reply

Hi Jean, 3 screws should be enough. However to be 100% sure and if you don't mind I recommend to print new part using our .stl files http://www.prusa3d.com/prusa-i3-printabl...

Jakub Dolezal -

I accidentally broke mounting clips on the Left Hotend Fan during assembly. Where can I purchase a replacement fan of the same specification?

Jesse Thompson - Reply

Hi Jesse, please contact our support for more information at info@prusa3d.com.

Jakub Dolezal -

Holes were too tight to directly try with fan. Used individual screws alone first to get them all started in their holes, then took them out, placed fan as pictured, and then they threaded fine without too much force..

Gary Sinkowitz - Reply

That worked for me too! :-)

Patrik Olsson -

After some effort i was able to get the two holes farthest from the motor threaded, but was able to seat the screws in the closest two so i'm leaving those off for now. My housing is orange since i've seen people refer to the color. Might consider having people test/start the fit for screws in the housing at the beginning of this section as by now it is an awkward assembly to handle and could be damaged.

Paul Matthews - Reply

The two screws closest to the motor do not seem to want to go in. So I only mounted the farthest two like the people that commented from before.

Anj Villarruz - Reply

I spent a long time trying to get these threaded. I finally found a way that worked consistently for all four: without the fan tap a screw with a hammer till it covers a thread or two, screw it in a bit, remove, place fan and screw into primed plastic holes

Garrett Carson - Reply

Happy to report this step went very smoothly for me. Only 1 screw posed a slight challenge threading, but a little pressure got it to engage.

Jeffrey Lazar - Reply

Black part - mine also two holes tight and two holes loose, clearly some issues still

Graham Legg - Reply

Same here... 2 good ones, 2 loose ones.

Russ Jaramillo - Reply

2 good holes (bottom near the nozzle) 1 tight hole (upper right near the motor) and 1 VERY TIGHT HOLE!

Marauderz - Reply

Procedure went smoothly. Using black parts.

Barry Dworkin - Reply

I would assume you guys have heard of thread forming screws? Could make this easier and more reliable.

David H. Brown - Reply

Another annoying stage where my trusty file came in handy. The screw hole openings were far too small/misshapen. I gently screwed the taped tip of the file into the holes slightly and this solved the issue.

Angela Pickett - Reply

Same Issues on the black printed parts. All 4 holes are too small.

Seth H Ellsworth - Reply

Please review this part, the fan holes specifically. The holes are too small for the screw and are not lined up well. This step took me far too long based on how simple it should be. Had to open up the two holes to align them, 2 holes closest to the wire tunnel, but not so much the screws would not thread in. Thanks.

David Bleakley - Reply

After reading these comments, I used a #38 drill bit in a hand held mini chuck to clean out the holes. The M3 screw threaded in nicely prior to mounting the fan.

Jackie T - Reply

On mine, two were the right size, and the other two were too small. I still put them in there, though. The sounds of breaking (praying it is excess filament in the holes) scared me.

Jacob S. - Reply

I also had difficulty getting the 4 screw into the holes. I used a 7/64” bit to enlarge each hole - just at the opening. The screws then started and tightened well.

Joe O. - Reply

orange plastic cracked when putting one of the 4 fan screws in, and It wasn’t due to over tightening, was not even tightened all the way. Hope it won’t be an issue moving forward.

Jeff D - Reply

My fan is not the same of the pictures, and it's not clear which side is the top side. It has a Prusa sticker on one side, that I thought goes on to, but then the blades seems to be inverted when compared with the pictures. How do I know which side is correct?

Rodrigo Basniak - Reply

Hi Rodrigo, the sticker should be always facing the hotend, therefore not visible on the assembled extruder. The air should be flowing in the extruder (use a piece of paper to check it).

Jakub Dolezal -

I didn’t see exactly how to run the wires ‘till later and had to re-wire. Better illustrations with points on the step to route wires between the fan and the orange part would be good - also I had to guess the orientation of wires within the fan and chose shortest wire path of the possibilities that the photo could be showing.

Dr. Ted - Reply

M3x40 (1 pcs) with M3n nut (1 pcs)
  • M3x40 (1 pcs) with M3n nut (1 pcs)

  • Printed manual might suggest to use screw M3x30, but the correct is M3x40.

  • Screw the nut fully

M3n nut? but I don't have any left

Emil - Reply

Hi Emil, there should be definitely extra nut in bag 9.SPARE.

Jakub Dolezal -

no more M3n. One in spare bag were used up.

Chung Lee - Reply

Hi, Chung, this is very unfortunate, are you sure there isn't any left in of the plastic bags? We are always providing more nuts and screw than necessary.

Jakub Dolezal -

Would be helpful to clarify that on step 24, only one of the m3x40's needs a nut. At this point, there are only 2 screws left, so I naturally assumed you put the nut on both.

Spencer O - Reply

Hi, Spencer, I'm sorry for the confusion, but it is written directly in the beginning of Step 24 and in the photo is also just one couple of screw and nut.

Jakub Dolezal -

M3x40 screws (1 pcs) M3x30 screw (1 pcs)
  • M3x40 screws (1 pcs)

  • M3x30 screw (1 pcs)

  • M3x18 screw (1 pcs)

  • M3x40 (1 pcs) with M3n nut (1 pcs)

  • Pay attention to use proper screws as indicated in the picture.

  • Place the M3n nut (1 pcs) into the trap

The M3x40 (Blue) screw should be notated in Section 4 during the Z-Axis set up. Step 24 has us put the screw in when it is unable to be reached without removing the upper mounting plates and gently pushing the Z-Axis out of the way to add the screw. If this is noted already during Section 4, then recommend making a highlighted bullet point about it there.

Chad Rice - Reply

I was just thinking the same thing... but you can just lower the X-axis by manually turning the Z-axis' threaded rods to be able to do this step. Maybe there should be a note about it.

Matty D -

Hi Chad, as Matty correctly stated you can lower the X-axis by rotating threaded rods of Z-axis manually.

Jakub Dolezal -

+1 I didn't see this picture until it was too late

Spencer O -

Just make a note in the instructions that you can lower the Z-axis if needed. Manually turning the screws both at the same time is enough. But if you don’t know, I guess it could be problematic here.

Wolfsblvt -

Could you manually spin the the threaded Z-axis 'bolts' in order to drop the whole X-axis assembly, in order to proceed?

clem - Reply

Hi Clem, sure you can carefully rotate the rods to lower the axis.

Jakub Dolezal -

M3x18 was short with mine so that I had to replace it with M3x20 nut, luckly I had it)

Emil - Reply

The 18mm is definitely right on the edge of being to short. It took me a while to get it to grab. I had to stick an exacto blade behind the nut and push it forward so the screw would grab it. I too stuck a 20mm in there, but it ended up bottoming out and actually pushes the parts away rather than pulling them together.

Randy H -

same for me. too short, use a 20

phil gerskovich -

Hi Emily, Randy and Phil, thanks for the feedback. You should use M3x18, using longer screw can cause problems, like breaking the extruder.

Jakub Dolezal -

Struggled with this too but the exacto blade trich and a little bit of force worked for me. Thanks @mochanic !

Codrin Kruijne -

This step is the worst part of entire assembly experience. The extruder is expected to be attached by 3 screws, but both M3x30 and M3x18 are too short to touch any thing. Therefore, entire extruder is fixed by a single screw (M3x40). Not sure if it will affect the performance, but it just makes me very uncomfortable.

Yuan Lin - Reply

Hi, Yuan, I'm sorry you have issues with the assembly. Please ensure you have placed all the nuts correctly. There must be something wrong.

Jakub Dolezal -

It should say that the nut with the red arrow has to be tightened with the screw at this step. There is no need to wait for step 25 or later.

Joe Man - Reply

Hi, Joe, you can tighten the M3x40. However, it is more convenient to tighten all screws at once and you can't do it in this step.

Jakub Dolezal -

I was short an M3x30 screw in my kit, robbing the spare bin I guess

Nick R Ellson - Reply

Hi, Nick. Yes please, use the bag with the spare parts.

Jakub Dolezal -

I also was short a M3x30. Love having the spare parts bag. This is the first time I have had to use it, but very thankful that it is there.

Joe O. -

Use the 40mm screw with the nut on it to pull the M3 nut into the trap.

Paul Betz - Reply

Hi, Paul, thanks for the tip.

Jakub Dolezal -

thanks for the comments and the note about using 40mm. just saved me a lot of frustration

DoubleC - Reply

Hi, DoubleC, did you have issues with inserting the nut?

Jakub Dolezal -

My kit was also short the M3x30 screw and had to obtain it from the spares bag.

Stuart - Reply

Hi Stuart, thanks for the feedback. All the other parts are ok?

Jakub Dolezal -

My kit was also short the M3x30, used the spare.

Angela Pickett - Reply

New kit and M18 too short.Had to use an M20 on “purple” screw

Dave Collea - Reply

Had to use a spare 40mm screw to pull the M3 nut foreward and jam it into the trap in order that the green 30mm screw would bite. Took me a rebuild of the assembly to understand the problem.

Paul McCherry - Reply

Hi

See the first pic. I was noot able to tighten the screw M3x18 screw (1 pcs) at the left arrow. When using the M3x20 screw, it tinghtened without any problem

Fredrik Hjärpe - Reply

Two things, (a) it should be noted we can turn the screws to lower it. This took me a sec to realize I could do. (B) having difficulty figuring out where the screw with the nut on goes…

FluffyKittenLoafs - Reply

The 18mm screw was too short when I tried to screw it in (in step 27). Thinking I had the wrong screw, I placed a longer screw (20mm, I think) into the slot. Being too long, it bottomed out (when it hit the opposite screw), and I realized my mistake.

However, when I tried to back out the screw, something (a burr on the threads?) has now stuck the square nut on the screw. Gradually applying more force trying to loosen the screw from the nut only succeeded in forcing the square nut to rotate within the extruder body

:-o

Now the nut rotates freely and I am unable to get any kind of pliers, wrench, blade into the slot that will grab the nut enough to allow me to remove the screw. Argh! I’m not sure what to do now short of drilling a larger slot to be able to grab the square nut with a pliers. Unfortunately that will likely damage the extruder body to the point where it may not be usable.

Any ideas?

L Mayer - Reply

Hi, I think it should be possible to finish the assembly and reprint the part or get in touch with our support, we can send you new extruder body ;) info@prusa3d.com

Jakub Dolezal -

Guide cables from the extruder as in the picture. Cables from the P.I.N.D.A. probe, the extruder motor and both fans must pass the X-axis between the lower smooth rod and the X-axis belt.
  • Guide cables from the extruder as in the picture.

  • Cables from the P.I.N.D.A. probe, the extruder motor and both fans must pass the X-axis between the lower smooth rod and the X-axis belt.

I found these steps with the cables a bit comfusing as the pictures are not taken from the same angle; check the orientation of the build!

Codrin Kruijne - Reply

Hi, Codrin, which part is confusing to you?

Jakub Dolezal -

The second picture makes no sense to me. How come the fan is closer to the top in the first picture and then comes around to be closer to the bottom?

Albert Chau - Reply

Arrange cables from the extruder upper part neatly in extruder cable holders. Make sure the cables from the extruder motor are guided as shown in the picture Make sure the cables from the extruder motor are guided as shown in the picture
  • Arrange cables from the extruder upper part neatly in extruder cable holders.

  • Make sure the cables from the extruder motor are guided as shown in the picture

"(see the photo with blue arrows)"

there is no photo with blue arrows...

Nik W - Reply

Hi Nik, thank you for your feedback. This part of cable management is done already at step 22. I've corrected the description for this step.

Jakub Dolezal -

The top right m3x40 screw will not set into the motor mount. I have re-seated the motor twice and it appears that the channel in the printed part is 1/2 a mm off. No way this will go int.

Wol Bar - Reply

Hi, Wol Bar, thanks for the feedback. Already forwarded to the quality assurance.

Jakub Dolezal -

Same here. Even with the housing not attached to the Y carrier I can't get the bolt to thread in.

Plebius - Reply

Hi, Plebius, can you please send photos to info@prusa3d.com? Thanks

Jakub Dolezal -

It should be noted that there’s a nice recess molded into the extruder mount into which the motor and fan wires can tuck into. If you don’t see that (which I didn’t initially), it looks like the cables are going to be compressed between the extruder and it’s mount. But I knew that Prusa wouldn’t do that, so I looked harder and found the recess. All is well.

Ira Schonfeld - Reply

Please tighten the screws in the order described below: First, tighten the top screw. Don't tighten  it fully!
  • Please tighten the screws in the order described below:

  • First, tighten the top screw. Don't tighten it fully!

  • Now tighten the left screw. This one you can tighten fully.

  • Tighten the right screw fully and then return to the top screw and tighten it as well.

  • After tightening all screws mentioned above tighten the last screw, which will be used for cable management.

No matter what I do I cannot get the top right screw to go into the motor. The motor is not line up by just a tiny bit. Will tightening the spring screws pull it closer or should I drill out the hole a tiny bit wider?

Andrew Cooper - Reply

Neither can I. The M3x40 screw is supposed to go into the motor mount. I took the motor half off and verified that it goes in. When I put it back the screw does not bite. I think it is too short.

Wol Bar -

Hi, Andrew and Wol Bar, can you please both send pictures to info@prusa3d.com? Regarding tightening spring screws, this affects only pressure on the filament.

Jakub Dolezal -

I posted an earlier comment on this problem. The nut in the cover tends to drop into the deep hole in the body and so is unreachable by the screw. You need to find some way to make this nut stay in the shallow recess of the cover. I tried pushing some of the PLA plastic in to hold it and then VERY CAREFULLY reassembled parts to this point. Success after 2 tries.

Merrill Albury -

The screw is long enough. The top right m3x40 screw will not set into the motor mount. I have re-seated the motor twice and it appears that the channel in the printed part is 1/2 a mm off. No way this will go in. The screw is shaving metall off from the part of the motor mount hole closest to the axle.

Wol Bar - Reply

Hi, Wol Bar, I'm sorry for the troubles. As mentioned above, can you send us photos? Thanks

Jakub Dolezal -

My 3x40 screw did not go in at first. I found that there was a small bit of plastic blocking the threads of the motor mount. Once that was cleared it went in without any problem and was plenty long enough.

Steve Sanford - Reply

Sadly I had no debris in threads. I can see where the bolt is etching the motor face, next to the hole. Thanks anyway!

Wol Bar -

Hi Steve, thanks for the feedback. The holes should be clear, I will forward this finding.

Jakub Dolezal -

Oh other thing is that I took the motor off and threaded the screw into it. It went in fine fine fine...

Wol Bar - Reply

Hi, Wol Bar, let me know if you managed to assemble this part. Thanks

Jakub Dolezal -

This all works out but a couple of extra pictures would probably help. Took a few tries. I thought I had screws that were too short but stick with it.

Twerd - Reply

Hi, Twerd, thank you for the feedback. I will try to improve the photos, so it is more obvious.

Jakub Dolezal -

I had the same problem as many including Yuan Lin (above), where two screws dont attach (M3x30 and M3x18)

They were resolved with two different tricks:

1) Unmount the extruder

2) Catch the M3x30 nut, by inserting it into the unmounted extruder i.e. without attaching it to x-axis. Then you can go as deep as need to catch the nut and pull it tightly towards the screw.

3) Ensure you havn't lost the square nut of the M3x18 screw and ensure that it is aligned with the hole. First by doing as in 2), which didnt work for me. Second by using the smallest Allen key to align the square nut so the screw can catch it.

4) Unscrew both screws, and mount the extruder on the x-axis

5) Try again mounting the screws very gently, hoping you dont push the nuts out of place.

It worked for me. Good luck!

Claus - Reply

Hi Claus, thank you for sharing your approach! ;)

Jakub Dolezal -

M3x30 screw doesnt screw in, all others are good, can i leave tike that?

Edvinas Tuomas -

We had the same problem and we dint even have another nut and we had to go to the hardware store to another one.picker 29 is the the one who picked our bags

Dave DeWitt -

Wow, what a tough step this is. Thank you Claus @ca2 for your guide, I had to do the same. I couldn't catch the nut for the blue bolt until I took off the extruder and aligned it by screwing in a bolt. At this point it could drift out of position as the nut was very loose. This problem was compounded by the necessity to jostle the wires into position which usually moved the nut out of position. So I had to steady hand it after alignment as if I was playing operation. That was the easy bolt. The green bolt was mad. The design of "wishing" the green nut would stay in place is a poor design. This needs a redesign to something less error prone. @ca2 's method of finding the green nut and pulling it forward eventually works but is flaky. Then you have to be very careful not to push it back out of position by very very slowly turning the green bolt. Good luck guys&gals, patience and a steady hand will prevail. BTW, I had no problem with the red bolt, that worked well.

Neil Martin -

I hade to unscrew the extruder and take a screw from the small fan to hold the green screw in place. then carefully put it all together again. and finaly put back the used screw from the small fan.

Patrik Olsson -

I got to this step and found that the 30 mm would not catch. After much agonizing I decided I need to disassemble and find out what was going on inside. I discovered that the nut that was supposed to be there had fallen out somewhere along the process. I put it back in and used hot melt glue to hold it there. (Fortunately you don't have to take everything apart to get to the screw. Just the two fans and one cover.

phil gerskovich - Reply

Hi Phil, missing nut is very often the issue. Thanks for sharing your finding.

Jakub Dolezal -

I had the same problem and was able to resolve it using the steps Phil posted. Thanks, Phil!

Pedro H -

I can't even see the point at which a nut is added there. As I understand it, this is the same deep hole from Step 6 which is used (badly) to hold the fan in place, but I don't see any point at which _another_ nut gets added there for the 3x30 to grip onto.

Ray Bellis -

never mind, I found it - it's the inside one with the red arrow pointing at it from Step 4. It was there, but it was stuck in a lot deeper than I expected, even when trying to retrieve it with an m3x40mm screw

Ray Bellis -

I had problems screwing in the one on the left - {step 24 M3x18 (pink bullet point)}. Look from the side and you'll see there are two square nuts. At an earlier stage I had used a screw that was too long and it had gone through both nuts. Take off the snail shaped impeller fan and replace the screw for a shorter one that only catches the first square nut. Replace fan. Fit screw M3x18.

David Truelove - Reply

Hi, David, please use screw lengths according to the manual. Using different length can lead to the situation like yours.

Jakub Dolezal -

I experienced the same problem. It's not possible to place the last upper screw - the holes (motor and plastic support) are not aligned.

The motor seems to be quite solid even without the third screw, so I wonder if I can use the printer if this last element has not been secured.

Can I safely run the printer??

Otherwise what is the solution you suggest?

Paolo Galli - Reply

Any chance to get a reply?

Paolo Galli - Reply

Hi Paolo, sorry for late answer. In case you aren't able to safely insert all three screws, please contact our support at info@prusa3d.com

Jakub Dolezal -

My right hand (green) screw is not connecting with anything. It must be that I have missed inserting a nut somewhere. I'm having trouble figuring out where that is. Can you tell me which step it is, or do I need to disassemble the whole extruder in order to reassemble it correctly?

Richard Rubinstein - Reply

Did you figure this out? I'm having the same issue.

Nicholas Nothom -

We had this problem too - for us it was step 4.

Max L -

Same question as Paolo. Can we run the printer without the top left screw being tight?

Jonathan T. - Reply

The square nut that the blue screw fits into really shouldn't be put in the slot in until this step. The instructions were for the square nut to be put in way back in Step 4. Raise your hands if you had that nut fall out like a dozen times between Step 4 and this Step. What I did earlier in this section was to put a piece of tape over that nut recess to keep the nut in.

Richard - Reply

Hand Raised! I finally let it stay out until this step. Of course, I had to screw the blue screw wondering why it wasn’t catching for a while before realizing that this was the step that I’d need to put the square nut in. However, even after getting the nut in there, the blue screw was too small. I ended up getting the next size longer from the spare parts bag to get it to catch.

Steve Gevers -

If the "top screw" won't engage, the motor and extruder assembly may be slightly out of alignment. I dismounted the extruder assembly and loosened the screw which holds the idler and the other screw which holds the motor on. The M3x40 then screws easily into the motor housing. I then tightened up the two loosened screws and took the M3x40 out. I remounted the assembly and the top screw went in without difficulty.

Iain Smith - Reply

Thanks for sharing your idea! When "top screw" did not engage in my case, I followed your steps and they worked perfectly.

DTop -

We were having a hard time getting the M3x18 to catch the M3nS, but tilted the whole assembly on it's side so the nut would fall to the front of the slot.

Lindsey Telford - Reply

I also got to this step and found that the 30 mm (green arrow) would not catch because the hidden nut has shifted. Solved it by using m3x40 from the spare box - screw it in all the way until it catches the nut, and then pull until the nut comes forward and sits in its place, then gently unscrew M3x40 and gently screw M3x30 instead. This way I did not have to disassemble anything.

DTop - Reply

Please update the instructions so that the cables guiding bolt is installed before the extruder goes up. The nut doesn't stay in its hole and is shifted by trying to catch it with the bolt. Mount this bolt (the one with the nut fully screwed in) completely before extruder goes up. It doesn't affect anything.

The M3x18 screw barely catches the square nut, you have to have that perfectly centered and press the extruder body and extruder mount together with your fingers and screw it in there until it catches. I felt it didn't catch more than a few threads.

Florian Ford - Reply

Hi Florian, thank you for the feedback we will have a look at it.

Jakub Dolezal -

I think I agree with this suggestion also. I was able to re-grab the nut by taking off the other nut and using the screw to pull it back out and seat the other nut again. Maybe just a reminder that you are using the nut you inserted before and be careful not to push too hard?

Neal Smith -

This step is quite difficult in getting all the screws aligned with nuts and/or motor thread.

John-Robert Yrjölä - Reply

Has anyone determined if you can actually proceed with less than all 3 tightened? I can't get the 30mm screw to catch regardless of my attempts. Is there an answer or has everyone just kept hammering at it until they were successful, or used a 40mm instead? I was going along pretty well until this point.

Wallace Saunders - Reply

TIP: I also had the 30mm bolt not catch anything. I think this is because I SHOVED it all the way in, pushing the nut deep into the cavity when I should have slowly threaded it into the hole. The nut you are shooting for is in a "shared" cavity with the deep nut from step 6. I must have pushed it into the cavity.

DTop's suggested worked. Use a 40mm bolt from the spare's back to screw in deep and retrieve the nut. Pull out the 40mm with the nut captured and pull it tightly to seat the nut back into position. Then screw in again slowly with the 30mm and you'll get the nut.

Jeremy Martin - Reply

I also needed to tilt the assembly toward the screw heads to get some help from gravity

David H. Brown -

Ugh. Just this step took me an hour trying to thread the central blue and green screws. Captive nut designs need to securely hold the nuts, please.

David H. Brown -

Had the same problem as some above with screw catching motor, holes were not 100% aligned. here's what solved it for me:

Loosened the two bottom motor screws but did not remove

loosened spring screws on filament idler pulley

Wiggled motor around, applied a tiny amount of force

Screwed m3x40 all the way into top right motor screw (careful, it wont go all the way)

Went back and tightened lower 2 screws and filament idler

Removed m3x40 screw from top right.

This was able to “align” things better for me so the screw would catch when attaching it to the rest of the assembly. The holes were off by about .5mm and wouldnt catch before this adjustment. Super smooth after this.

I’m convinced this happened because I left the bottom screws loose and the pressure from the spring screws adjusted to 13mm pushes the motor slightly out of alignment.

Scott - Reply

Got to this point to see that the blue screw didn't catch the hex nut. After going all way back I noticed the hex nut flying around in the hole. Too bad. It's crucial not to apply any pressure when fixing the screw.

Alexander Buschek - Reply

Happened a second time. Now I'm not willing to disassemble it a second time. Used a 3mm threaded rod to pull the nut back in place and tried again to most gently insert the screw. Worked after 2ND attempt. There is room for improvement.

Alexander Buschek - Reply

I had the same problem with the m3x40 screw, i had to unscrew the motor, and screw it again lining first the m3x40 screw, i had to unscrew the ones with the spring so i could move the one with the fan nozzle, then screw the motor again and repeat, and it assembled like charm, very complicated altough, i could be helpful to add this in step 10, screwing a m3x40 to align the motor correctly

Carlos Talamantes - Reply

After I also had the same problem as others with the 30mm screw not threading into a nut, I got an idea. This nut can easily be pushed out of its trap and into the void of the nut trap of the large fan top screw. I recommend some way to fill the void. I am really enjoying this Build! Thanks guys!

Jared Anderson - Reply

This was the hardest step so far. The two middle ones didn't want to thread. I read all your comments and was able to use the longer one to get the nut set for the right middle and for the left as well, being careful and slow to put the extruder on so the nuts didn't move. Got it on finally after far too long.

Josh - Reply

Most annoying step so far! SO much mucking around and time wasted! Left screw would not thread onto the nut until I took the piece off and threaded it, then with surgical precision returned the piece and threaded the screw through as instructed.

Angela Pickett - Reply

Is the screw for cable management suppose to attach to something in the extruder? I have all the other screws in, in the correct order but it doesn’t seem to be tightening.

Tommy Fisher - Reply

Hi Tommy, yes there should be a nut on the other side, helping you to tighten this screw for “cable management”, see step 24, second picture.

Jakub Dolezal -

My solution for the M3x30 screw not screwing was simple.

I’ve removed that screw with the help of a magnetic screwdriver and then screwed the M3x40 until the nut was aligned.

Then I removed the M3x40 and inserted the M3x30 again and it was a perfect fit.

No need to disassemble the extruder and nothing else actually. Problem solved in less than 5m.

My 2 cents.

António Cabral - Reply

The last bolt doesn’t seem to want to thread in. I even took the nut off to see if it was just to short with the nut on and still not threading in.

Seth H Ellsworth - Reply

I am having this same problem. the hole appears to be too large. What should I do?

Becky Diamond -

I am having the same problem. It appears the hole is too large.

Becky Diamond -

Hi Becky (@moabgohan), please recheck all nuts are in place. In case you still have issues with the assembly, please take some photos and upload them to the “Answers” section. Thanks

Jakub Dolezal -

same problem for us as well. can i just glue it?

Kimberly Hobson -

Hi Kimberly, you should be able to assemble the printer without using a glue. Please check again all the nuts are seated properly.

Jakub Dolezal -

For those of you having trouble with the top screw not engaging the motor, here is my advice. Use the pliers to lever the printed part slightly. To do this, you want one of the jaws on the motor near where the screw is going, and the other jaw on the printed part between the idler and the motor. Squeeze GENTLY while attempting to pot the screw. This will help the hole in the printed part line up with the hole in the motor.

Stuart Crowley - Reply

I think it would be helpful throughout this guide to say if screws are being inserted into captive nuts, or acting as self-tapping screws into the plastic. I often wondered if I missed a captive nut step (or if one fell out) in a non-accessible, not visible, place.

I agree that inserting captive nuts in steps as close to their being used is much better than doing it many steps earlier. As for the 18mm (blue) screw, it BARELY bites if you use an XACTO blade or equivalent to press the square nut toward the screw as you turn it. The problem seems to be that there is some front-to-back play in the captive nut well that can easily move the square nut our of reach of the 18mm screw.

Lane Hauck - Reply

For us, the red nut from step 4 had rotated about 45 degrees and so was not engaging with the M3x30 screw on the right hand side. Fortunately, to fix it, we just had to take off the two fans to be able to access the inside.

Max L - Reply

Same for me as with Max L above. I disassembled to find the screw for the M3X30 out of alignment. It’s likely that I pushed it out of position myself by shoving the M3X30 in there, assuming that the nut was securely in place. It is not — the recess is large enough to allow the nut to shift and turn out of alignment. So the second time, I seated the nut with a small dab of petroleum jelly as recommended by Walter in Step 4, and slowly, carefully inserted the M3X30 while rotating the screw so it would catch without being pushed out of whack. That did the trick. Wondering if a shallower recess and slightly longer screw would be better here.

Van Albert - Reply

I found my missing M3x30 screw !! I had trouble getting the upper right corner screw in - like so many others commented. After investigating, it wouldn’t go in because there was already a screw in the hole behind the extruder.. It was my M3x30 screw that I thought I had lost. Looking back to step 10, I should have only put 2 screws into the motor mount. I had put a third one there, thus it was in the way of the M3x40 that was to go in the upper right corner. I removed the screw from the motor mount and then the M3x40 in the upper right corner went in just fine. :)

Joe O. - Reply

Guide the cables as shown in the picture.
  • Guide the cables as shown in the picture.

  • Make sure that the wires from the thermistor are going above the heater wires.

  • Running them below will cause issues later, don't do that!

mine were already tied together with a zip tie in that spot…

Manus van den Berg - Reply

Mine too. Nice addition. Could be explained here though :P

Wolfsblvt -

One of my red heater wires fell off while I was trying to position them according to the picture. What should I do?

Jacob Vanden Bosch - Reply

Hi Jacob, this is unfortunate, please contact our support and order a new heater.

Jakub Dolezal -

I can’t see what is going on in this picture. One more picture might help

Kristian - Reply

Hi Kristian, please ensure the blue wires are above the red ones.

Jakub Dolezal -

Insert a ziptie (longer one in package) in the right side of  the X-carriage so that cables from the extruder motor and the fan are below the ziptie and held in place. Double check the orientation of the ziptie. Once all cables are neatly arranged,  finalize it by tightening the ziptie and cutting off the excessive piece.
  • Insert a ziptie (longer one in package) in the right side of the X-carriage so that cables from the extruder motor and the fan are below the ziptie and held in place.

  • Double check the orientation of the ziptie.

  • Once all cables are neatly arranged, finalize it by tightening the ziptie and cutting off the excessive piece.

  • Use pliers to cut off any excess ziptie.

Pay attention to the heater wires. They must go in the notch at the bottom of the extruder housing. You will miss it if you don't pay close attention to the pictures. If you don't do it the wires will hit the frame. This should be included in the written instruction and maybe a picture will an arrow pointing to it.

Paul Betz - Reply

Should I be cutting the small ziptie that holds the thermistor wires to the heater wires? It doesn't seem to be doing too much good, and it's causing the silicone rubber insulation from the two wires to bunch up instead of going up into the notch nicely. Seems like the extra silicone insulation will be held in place by the bigger cable management ziptie now. (Where it wouldn't have been before during shipping.)

Andrew Ahlfield -

Hi, Paul, thanks for the feedback. We will try to improve this step.

Jakub Dolezal -

Hi, Andrew, please follow the manual and do not make any adjustments or you may damage your printer.

Jakub Dolezal -

When I tried to get my heater wires to go into that notch they snapped off :(

Jacob Vanden Bosch -

Should the wires coming off the extruder end be up against the extruder once zip tied? Extruder wont melt through the wire casings?

Artur Shlifer - Reply

Hi Artur, nozzle nor the extruder should be in direct contact with the cables. Can you please send pictures to info@prusa3d.com?

Jakub Dolezal -

This step is missing the very important instruction of what to do with the heater block and thermistor wires, as already pointed out by Paul, the picture shows that they need to be slung using the zip tie. And as Andrew pointed out, it can't be slung normally because there's a zip tie tying up the tip of the heater & thermistor wires preventing it from going into the groove so that it's higher than the print nozzle.

Then there's the question of if we DO move the heater and thermistor wires through the groove it'll touch the heater block, what then?

Here's what I've done.

- Cut the small zip tie

- Carefully arranged the wires into the groove and slung it through the big zip tie

- Carefully arranged so thermositor wire doesn't touch heater block, the wire looks insulated to me though so maybe it might not matter much?

Marauderz - Reply

Hi Marauderz, we are working on it. I already talked to the production team about the best position of the zip tie, which comes with the hotend. As a result, it shouldn't collide with the X-carriage and you should be able to lead the cable through the opening (slot) in the lower part of the X-carriage.

To answer you question it is better to arrange the cables in a way, they aren't touching the heaterblock.

Jakub Dolezal -

I agree the small zip tie prevents the heater cables sitting flush into the lower slot

lee ashmore - Reply

Hi Lee, I'm aware of it, we will make an adjustment.

Jakub Dolezal -

Hi Jakub, how are you coming along on this?

Do you have an update as of yet?

Dennis Sladek - Reply

Best to leave some slack in the heater and thernistor wire and curve them around the heater while the large zip tie is loose. It's hard to do because where the heater wires are crimped ends up in the slot. I then zip tied all 3 wires together on the curve you form to keep the thermistor wire from going back to the heater block when ithe head is moving around later. Make sure all wires are above the nozzle so they don't rub your print. I have pics if needed

Chris Blanchard - Reply

I just did as Chris suggested above and it worked out great.. I cut the small zip tie first and was able to “curve the wires away from the heater block.

Dave Collea - Reply

Thanks, Chris ! I had already cut that small tie around the heater wires because it was in the way. But after reading the note from Chris, I noticed my heater wires were against the heater. I cut the big zip tie and did it again with a slight bend in the red heater wires so they are not touching the heater. Once again, the comments saved me !!

Joe O. - Reply

I received 145mm long zip ties with my kit, but they seem to be too short to complete this step. Is there something I'm missing?

Alex Spens - Reply

Same here. The 145mm zipties seem to be too short. Also, I’m still uncertain as what to do with the ziptie that holds the heater wires…

Sebastian Comanescu - Reply

The zip ties should be long enough, where exactly is the issue? While gathering the cables?

Jakub Dolezal -

The zip ties in my package were 142mm end to end. They were NOT long enough. I ended up using two in series to make the loop to secure the cables. I also removed the zip tie from the extruder/thermistor wiring, made a small loop away from the heating element, and added another zip tie can the middle of that loop to prevent any contact with the hot parts, and also to make sure there were no loose wires in that area.

Mattew Farr - Reply

Argreed, there is simply no way to use the provided (single length) zip ties to do this step. You can get the ziptie into the position shown in the photo - but there aren’t enough teeth on the plastic for it to zip into place - so it just comes undone.

If you didn’t want to add a longer zip tie for this one place, it looks like you could redesign the plastic part so that the upper hole that the tie goes through would be a centimeter lower - then you’d have 2cm of ziptie to spare….which would be plenty.

Stephen Baker - Reply

The problem with the thermistor wires and the ziptie that holds them to the heater wires is that WAY back when we tied those together, there were no instructions about the precise placement of the tie…when in fact it’s rather critical. It can’t touch the heater block and it can’t get in the way of the cable channel - and, IMHO, the thermistor wire should be routed on the outside of the heater wire so that the red insulation can protect it from the heat.

Stephen Baker - Reply

Must have used the longer “one” in the package. Please give extra.

Kim Vojensky - Reply

Be extremely careful with the hot end wires. I broke one of the the heater wires while trying to manipulate it so it didn’t touch and trying to get the zip tie to catch. Definitely go with the two zip tie method.

Reese - Reply

Extruder cable holder Make sure the cable holder is oriented upwards. Place the two halfs of the cable stiffener on the M3x40 screw.
  • Extruder cable holder

  • Make sure the cable holder is oriented upwards.

  • Place the two halfs of the cable stiffener on the M3x40 screw.

my cable holder didnt close since there was 1 mm space between the pieces.

Angel Spy - Reply

Hi Angel, it is important if the cable holder sits tight on the screw head, so it can properly support all the cables. Can you confirm that?

Jakub Dolezal -

using a nail cutter to cut off cable ties is easy especially in tough to access places!

Abhinav Ram - Reply

my kit only has two left facing cable holders. They are exactly the same and when attached one is pointing up and the other is pointing down.

Jesse Crystal - Reply

Looks like ours got mixed up in packing. I’m currently holding two right facing cable holders.

Edwin Robertson -

My black pieces doesn't have any guide for screw, just a solid part

Sergio Fernandez - Reply

Hi Sergio, please send pictures to info@prusa3d.com. My colleagues will solve this.

Jakub Dolezal -

Hi Jakub,

mine came without either of the 2 halves of the cable holder. Can you advise please?

Many thanks.

Trevor Clegg - Reply

Hi Jakub,

I've already tried to post this but it's not showing in the comments, so here it is again.

I received neither of the 2 halves of the cable holder. Can you please advise?

Many

Trevor Clegg - Reply

Use two zip ties for fastening. Use pliers to cut off any excess zip tie. Use pliers to cut off any excess zip tie.
  • Use two zip ties for fastening.

  • Use pliers to cut off any excess zip tie.

The heads on these two zip ties interfered with the left frame side or the Rambo box when I was calibrating. I suggest turning them around so the heads are on the other side.

Gordon McDonough - Reply

Hi, Gordon, thanks for the suggestion. If the "heads" of the zip ties are facing down, it shouldn't be interfering with the RAMBO door.

Jakub Dolezal -

There are two NYLON filaments  included in the kit with lengths 50 and 30 cm. Both have Ø 3 mm. For this step please use the longer one and DON'T CUT any of them!
  • There are two NYLON filaments included in the kit with lengths 50 and 30 cm. Both have Ø 3 mm. For this step please use the longer one and DON'T CUT any of them!

  • Push it all the way down. If you experience difficulties when inserting the filament use pliers to make a sharp tip on the filament.

  • The filament is for the support of the whole harness. Don't cut it, it'll go all the way with the wires to the cover for electronics.

  • Note the correct orientation of nylon filament, it needs to point up as shown in the picture!

  • Nylon filament is pictured in orange colour, but in your kit can be the black version, which is the same, just different colour.

I had to use a jeweler's file to open up the hole a bit. I think my Nylon may have swelled during shipping. The hole diameter was 2.75mm and my nylon was around 3mm.

Robert Klein - Reply

Hi Robert, did you make a tip on the nylon as suggested?

Jakub Dolezal -

I had the same problem and solved it with simple sand paper, by sanding down the piece of filament until it fit in the hole. I would suggest others to use this method, as you dont risk to destroy the 3D printed part. In the worst case you cut off the piece of your filament that was sanded too much.

Claus - Reply

Hi Claus, making a tip on the nylon didn't help?

Jakub Dolezal -

Jakub, the problem wasn’t starting it but pushing it all the way. Too much binding. I finally got it to go in almost all the way by using the pliers to grab near the extruder and push just a little at a time. Black nylon into orange part, if that matters.

David H. Brown -

"All the way down" is about 2 cm, as far as I can tell, based on using a hex key as a probe. I also had to use sandpaper to make it possible to insert.

Tony Hansen - Reply

Hi Tony, thanks for your comment.

Jakub Dolezal -

Got a small Philips screwdriver with a shaft diameter of 2.96 mm. That was enough to clean up the hole while maintaining the tight fit. To insert it I sharpened the tip with an exacto knife, lubricated it with natures #1 lubricant, saliva. Pushed it in with the pliers and rotate it in the correct position with the pliers. Learning new tricks everyday. (new for me... LOL )

Waldo - Reply

Hi, Waldo, thanks for sharing your approach. Important is to create the tip, so the NYLON slides in.

Jakub Dolezal -

Thanks Waldo. You screwdriver trick worked for me!

Gael Lafond -

My filament was 3.05 mm but I had no issues inserting it.

Paul Betz - Reply

Also might want to note that it is the longest piece of nylon as there are two different sizes in the kit and seeing as someone like me didn't know how long 50cm was. Makes it easier are us simpler folks. lol

Paul Betz - Reply

Hi, Paul, we will edit the manual, so it is obvious, which NYLON to use. Thanks

Jakub Dolezal -

Am I the only one who saw 2 pieces of filament and thought to himself, "oh, sh*t the filament broke!".

It looked to me much shorter than 50cm, so I tried connecting them together using a heat gun. didn't work (fortunately), and I had to cut 1cm from each part.

Please clearly state that there are *2* filaments, and that you should take the longer one, and besides, this part should be clearly marked in the beginning like all other parts that are required for the assembly. If each filament was marked with a unique part #, I wouldn't have made this mistake.

Udi Finkelstein - Reply

Hi Udi, I'm sorry for the confusion. I will edit the manual. Thanks

Jakub Dolezal -

Should note that the filament is in the parts box, and not included in the E-Axis bag

John Mangan - Reply

I had no issues inserting the filament. Might also want to note that color can be different than what is shown in the picture. Mine is black.

John Mangan - Reply

Hi, John, thanks for the feedback. The note will be added.

Jakub Dolezal -

How much is all the way? Only a few mm in my case, but as it is quite snug (had to sharpen filament to get it in) I trust it will hold.

Codrin Kruijne - Reply

I only have a single piece of 3mm filament that is 500mm long. Should I cut to produce 160mm and 100mm pieces?

Robert Haddon - Reply

same here, I have a 300mm and a 500mm...

benallen -

The printed assembly instructions says that we should use the 50cm without cutting it. Cheers

benallen -

My long one is 510 mm, my short one is 300 mm.

Gordon McDonough - Reply

my kits did not have the filament. Anyone have suggestions?

Kirill Gelman - Reply

The filament looks rather like weed whacker cord and I'm guessing something like that would offer the same sort of support. See comment below where I posted a picture of ours sanded down.

Steve Trefethen -

We had the same issue as Robert Klein and several others in that the filament was too large to fit despite a good effort to create a sharp tip with pliers (no go). We followed Claus' suggestion and used sandpaper and that worked just fine. Here's are the two ends after sanding: https://twitter.com/stevetrefethen/statu...

Steve Trefethen - Reply

My nylon filaments are BLACK not orange. The 30 cm piece is only 27 cm long. Pretty far off. I'm hoping this won't be a big problem later

Dave DeWitt - Reply

Hi, Dave, there is a note regarding the nylon filament colour, see the last bullet point of this step. The length 27 cm is still enough.

Jakub Dolezal -

I have 2 black ones which are both 50cm long - I hope that nobody else got 2 30cm in their package.

Michael Berneis - Reply

Hi Michael, please take one NYLON and cut its length to 30 cm. I'm sorry for shipping longer length.

Jakub Dolezal -

If you have difficulty to get the fibre in the hole, a Dremmel (if you have one), is ideal for shaving it down to size in a controlled way. The depth of the hole is 15mm.

Mark - Reply

My Nylon cord was thick as well; I sanded it down a small amount (still > 3mm afterwards) and make the tip pointed. I still had difficulty getting it all the way in the hole, so I used the pliers to grab the Nylon close to the hole so I could force it in without bending it too much.

Dean - Reply

The hole is way too small for me. The 2.5mm hex key doesn't fit in the hole and the filament I have is 3mm. Cutting it into a tip means just some of the tip goes in. The 2mm hex key goes in. I've tried wiggling that around, hoping that it's just the entrance that is too small, but that hasn't helped.

Neil Martin - Reply

I have a screwdriver with a tip that is 2.8mm diameter, but it widens after 10mm so I could only drill 10mm into the hole. After than I could put the 2.5mm hex key 10mm into the hole but no further, so it looks like the hole's diameter is too small throughout its entire length, not just the entrance. The 3mm Nylon still does not fit, so I'll need to drill it wider, or file down the filament.

Neil Martin - Reply

It would be useful if the instructions specified what "all the way down" means. Someone else mentioned this: the response was thanks for the comment. More useful would have been the distance of all the way down.

Jeffrey Lazar - Reply

I dremeled with a 2.8mm drill bit which opened up the hole enough for the 3mm nylon.

Neil Martin - Reply

The hole was way too small on mine as well. And before you say, "cut the tip", that's not the problem as many have already stated. The entire hole is a smaller diameter than the nylon. A pointed tip does nothing to solve this.

Ryne - Reply

Ryne thanks for the feedback, I will talk to guys in production about this. We are assembling printers on a daily basis and I haven't heard about it so far.

Jakub Dolezal -

I can't find my filaments. Where are they located?

Albert Chau - Reply

Hi Albert, the nylon filaments are part of the main box, please check it is not hidden in some gap between the cardboard box.

Jakub Dolezal -

I have the same issue as Albert. My filament is missing as well. I've gone over every box over and over again. Nothing :-( I do have some 2.85mm ABS filament. Would that work as well? Or is that less tough than nylon?

Marcel - Reply

Hi Marcel, please use NYLON string. You can use for example the one used in string trimmer, just check the diameter. Since it will be bent many times, it needs to be flexible.

Jakub Dolezal -

Same issue as many people, hole to small to fit the NYLON. Making a “tip” didn’t help. Had to sand the filament. (I’m having the black kit.)

S.W. Bijleveld - Reply

Hi Sjoerd, thanks for the feedback. I will talk to the production team.

Jakub Dolezal -

Same issue - filament too big for the hole, had to sand it

Angela Pickett - Reply

Hi Angela, thanks for the comment, already being discussed with the production team.

Jakub Dolezal -

Does it have to be super snug? Mine is not snug but I guess that’s okay?

Monique DeSalvo - Reply

I had the same issue. Try to avoid opening the hole.

I used a tried and proven woodworking tip. The same as inserting a wooden peg into a joint.

1. Trim the excess “edge” on the filament

2. Cut a “very slight” angle on one area

3. Cover the tip, about 3mm with candle wax

4. It should slide in with less force, though you still need to be careful.

Lloyd Tribley - Reply

Same issue as Monique DeSalvo my filament was not sung, but too loose. It sounds like they corrected or over corrected the too tight issue.

Shumone - Reply

My filament went in easily and is rather loose. later, if it appears that the filament needs to be anchored, I will glue it in place.

Joe O. - Reply

The key problem here is that the instructions don’t say how deep the hole is…Mine went in about 1cm - other people here claim 2cm. I doubt it’s critical.

Stephen Baker - Reply

Wrap the spiral wrap (the largest and the longest one) around the cables and the nylon filament. Start with cables from the upper part, after 1 turn add cables from the hot end. Double check by moving the extruder fully to the left or right that spiral wrap does not interfere with the printer frame.
  • Wrap the spiral wrap (the largest and the longest one) around the cables and the nylon filament.

  • Start with cables from the upper part, after 1 turn add cables from the hot end.

  • Double check by moving the extruder fully to the left or right that spiral wrap does not interfere with the printer frame.

  • Use zip ties and tighten the wrapped cables and spiral wrap. Tight the spiral wrap to the cable stiffener.

  • Use one piece at the beginning of the spiral wrap.

  • Tighten zip ties carefully, too much pressure can damage cables inside! Don't tighten the zip tie over cables only!

You may want to change

"Wrap the spiral wrap (the largest and the longest one) around the cables."

by

"Wrap the spiral wrap (the largest and the longest one) around the cables AND nylon piece you added before" lol

Alex Tutusaus - Reply

I was just about to say the same thing. Didn't realize at first the nylon needed to be wrapped with the wires so I checked Step 34 to confirm where it went.

Paul Betz -

Hi Alex and Paul, thanks for the feedback. Note regarding nylon added to the description.

Jakub Dolezal -

The picture shows the cable holder also is included in the wrap. Here is what I did: one wrap of cable wrap around only the upper cables; then one wrap around all cables, the filament, AND the cable holder; then continue wrapping around all cables and the filament. I used 3 cable ties: around the wrapped upper cables; around the cable holder and all cables; and art he top of the all-cables section. I found it easiest to do all the wrapping and the realign things as I tightened each cable tie. Seems to me to be likely to work best if the cables are under the cable holder, rather than on either side of the cackle holder.

Joe Foley -

I know this will sound foolish to everyone else but I would benefit from a video of wrapping the chords, filament and support.

DoubleC - Reply

I agree, that or revise the language and the picture to show what is meant by

"Start with cables from the upper part, after 1 turn add cables from the hot end."

Including mention of the cable holder is necessary as well. I see it from the pictures, but it really is unclear what you want us to do with the first turn of the wrap.

Andrew Ahlfield -

IMPORTANT: All the cables must be placed to the right of the cable holder (to the left when looking at the printer from the back, as it is positioned at this step). If you put some cables to the other side, it will prevent the extruder from homing (moving all the way to the left) because the cable "bundle" will collide with the RAMBO box. There is very little clearance there.

Gael Lafond - Reply

I agree with this. Very IMPORTANT. Had to come back to this step and correct it after completing everything and doing "Preflight Check" section. Cables should be routed to the left of the cable stiffener in this step.

DTop -

A video would be really good here to see the wrapping. I'm not sure if I got the start covered enough.

Kiel H McGettigan - Reply

Hi Kiel, please see my answer below.

Jakub Dolezal -

I agree with the video idea. When I move the X axis all the way to the idler side there is a very small amount of interference with the cable coming from the position sensor even though I have it tucked well into the channel where it is supplosed to go. On the motor side everything has plenty of clearance and the limit switch trips just fine.

Dave DeWitt - Reply

Hi Dave and Kiel, thanks for the suggestion. We will consider making the video.

Jakub Dolezal -

I can move the extruder to the left side till hitting the endstop without problems, but I cannot move the extruder on the right side till the end, because the cables hit the frame. There are about other 3 mm, that cannot be used.

Is this OK?

Maybe this is above the usable max X position and I can ignore it?

Enrico - Reply

Hi Enrico, in general just check if the Nozzle can reach the edges of the heatbed below. In your case, the "right" side of the X-axis reaches the edge of the heatbed way before the beginning of the frame.

Jakub Dolezal -

Hi Rrusa

I routed all the wires per steps 28 to 34 but I noticed that the power cables of the heating element (with red sleeves) are sharply bend directly after the ceramic white material (isolating material) of the element. If needed I can send a picture.

This wires are very stiff so its not possible to create a 'relief wave' in the wires.

Looks as if when heated, the stress on the wires may be very large and the wires (or ceramic casting) can break or create an electric short.

Should I fix it?

If yes what should I do?

Shachar Rotem - Reply

Agree - I could not 'shape' the red insulated cable to turn 90 degrees and pass through cable guide held by zip tie - red cable sharply kinked rather than contoured around the corner

Albert Alonso -

Could you clarify what is meant by "the hot end" please?

Mark - Reply

Several people (including this one) found the wrapping instructions confusing in Step 33:

- from a geometrical standpoint, wrapping the first turn around the top wires puts the 2nd turn outside of the cable stiffener reach,

- the instruction doesn't mention the stiffener,

- the picture shows the 1st wrap also catching the heater wires, in contradiction with the written instructions.

Well...what to do? Hard to say.

The easiest way is to tie the nylon rod to the stiffener first, then follow with the 1st wrap (see also the pictures at https://drive.google.com/open?id=0B0gHmu... for reference ):

1. attached the nylon rod to stiffener with a tie

2. 1st turn around the top cables, stiffener, and rod altogether

3. secure the 1st turn with two ties

4. 2nd turn catches the heater wires

Looking at it, one would realize that the stiffener geometry (the lower part, like an inverted V) and angle was meant as a guide for the nylon rod: rod diameter fits the channel size.

Ferdinand Badescu - Reply

What I did, which worked quite well for me, was loosely, yet snugly, tied a zip tie around all of the wires to be wrapped. I then organized the wires in a neat fashion ((for instance the nylon filament was always on the top, the heater wires were always to the left, the motor wires were always to the right)). Starting at the extruder assembly, I moved my way down the wire, keeping the wires organized in a consistent orientation. When I organize about 3 or 4 inches, I would slide the zip tie to the end of the organized wires (furthest from the extruder assembly), and would wrap that 3-4 inches. Then I would continue to organize the rest of the wires, starting from the zip tie and moving toward the loose end of the wires. This ensured that all of the wires were straight and not tangled, and also ensured nothing was kinked. I hope this helped.

Jason Wright - Reply

+1 for not having any cables to the left (looking from the front) of the black support (round the bolt sticking out), got to pre-flight checks to find that the X-limit-switch would not activate because the wires hit the RAMBO case! From back of the printer it is to the right of the support.

John - Reply

I agree. My cable bundle does press against the RAMBO case, but not so much that it prevents the end stop switch from triggering. @jakoob or other Prusa representative, time to update the instructions?

Anton Eliasson -

Hi Anton (@antoneliasson), in the instructions is written to check manually the endstop is triggered and we are also discussing design change to prevent collision between cables and the door.

Jakub Dolezal -

Why oh why are the pictures at angles where we can’t see what we need to see?..

Jacob S. - Reply

I did not like the way the zip tie at the extruder head looked like it would rub the wires. I added a small section to spiral wrap (I had some small pieces on hand) over the zip tie to protect the wires.

Rob Gabel - Reply

I was concerned that the zip tie at the extruder head would rub the wires. I took a small piece of spiral wrap that I had and put it over the zip tie to protect the wires.

Rob Gabel - Reply

The instructions say to check that the cable doesn’t hit the frame - but FAR more important is to check that the X axis limit switch still “clicks” when you slide the extruder all the way to the right. Making this check explicit now saves a ton of messing around at the end when the printer refuses to “home”.

Stephen Baker - Reply

Check for free movement of the X-carriage and inspect cables in the full left and right positions.
  • Check for free movement of the X-carriage and inspect cables in the full left and right positions.

  • Once you are satisfied with organisation of the extruder cables finalize spiral wrap to the full length.

  • Separate the filament at the last whirl of the spiral wrap.

Why separate the filament at the end?

Michael P Graham - Reply

Hi, Michael, later on, you will place this part of the filament into a special holder on the electronics cover and therefore all the load will be transferred through the nylon and not through the cables.

Jakub Dolezal -

Congratulations! You've just assembled the extruder.
  • Congratulations! You've just assembled the extruder.

  • You can continue by assembling the LCD in the next chapter - 6. LCD assembly

Nut in the hole problem Step 4, with 2 reworks to get it fixed. gave me great experience with assembly/disassembly of the extruder assembly. Also made my completion time for this assembly 4 Hrs and 25 Min

Merrill Albury - Reply

After completing all steps, the X-Carriage is now unable to reach the X-EndStop. No more "click" when moving the X axis to the end. The extruder cables collides with the frame. Is this normal?

FranPi - Reply

Hi FranPi, while looking on the "rear" part of the printer, the cables should be at the center of the extruder or slightly to the left.

Jakub Dolezal -

This was very frustrating, all the malaligned screws, the bad description of the extruder wiring harness.. I hope I didn't break anything!

Marauderz - Reply

Hi Marauderz, thanks for the feedback. I'm constantly working on updates and the things, you've mentioned are being solved already ;)

Jakub Dolezal -

Same here. The other sections prior to this, I felt pretty confident about what I was doing - even if I was hitting little snags here and there. With this part, however, I kept thinking I had to be doing something wrong with as much as the parts were squeaking due to holes being just slightly too small.

Bill Robitske, Jr. -

2 hours 6 minutes.

Only problem was the cable organizer screw that didn’t fit. We ended up adding a little glue to hold in place.

Kimberly Hobson - Reply

Finish Line

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25 Comments

Step 14: the hole in the idler is a bit to narrow, so the bearing does not turn well.

Anyway, the printer runs without problems since the first print, so it doesnt seem to be a big problem.

Robert S. - Reply

Hi Robert, which part was a bit narrow? Can you share a link with a picture with highlighted part? Anyway, I'm glad the printer works for you.

Jakub Dolezal -

@jakoob

https://d17kynu4zpq5hy.cloudfront.net/ig...

The hole within the green circle where the 625 bearing gets in.

Robert S. -

2hrs on this section. It's fairly tedious and I ran into a couple issues.

The space between the idler bearing is about .01-.015 to narrow and had to be shave with an exacto knife so the bearing would turn freely.

the 18mm screw for the extruder to the X axis body is to short to start it easily mainly because the slot that the square nut slides into is way to big and allows the nut to fall right out, so I had to push the nut forward pretty hard to get it to catch the screw.

Randy H - Reply

2.5 hours... No problems

James Miller - Reply

Three hours, but posting pictures. One of the four small fan screw holes chose to be a little difficult, the one nearest to the wiring. Once started, it went ok. Alignment of the extruder to the x-axis mount was a little tedious too, A couple of the nut holes were actually a little big and the nuts fell out a couple of times, but that resolved itself too.

Brian S - Reply

2,5 hours due to loose nut that made it impossible to attach the fan; had to go back a couple of steps and use the exacto knife technique, after which all went well!

Codrin Kruijne - Reply

Thanks a lot! This documentation is awesome. A very, very good job!

The screws for the Pinda probe aught to be M3x12mm. Then they would reach the nut and still be short enough to stay within the printed part. The M3x10mm screws supplied do not reach the nut! I have replaced them with M3x12mm on both my Prusa machines to be able to secure the probe.

Thanks

Anders

Sweden

Anders Wikström - Reply

Hi, Anders, thanks for the feedback! It is nice to hear you liked our manual :) You should be able to reach the nuts with M3x10 screws, is the P.I.N.D.A. probe properly seated in the holder?

Jakub Dolezal -

I really enjoy building this printer. The resources and prusa team are great. They always answer questions and do a lot to make sure everyone understands what to do! This guide however was a little hard to follow and could be updated to be easier to follow.

Hayden P Mcgarity-Bashiri - Reply

Toughest part for me so far -- 3 hours or so across the day.. Online guide was great as were the comments .. Labelled the 3 Red &Black two wire clips wires before wrapping just to be sure .. Similar issue with some wires hitting the frame when moving extruder far right, but do not believe it will be an issue during printing.. Will watch it.. Start on the LCD tomorrow

Gary Sinkowitz - Reply

The bit with the nylon was a struggle. Can you guys include how deep you expect that piece to go in? I still don't know if it's all the way in or what. I know you can't force the nylon to be an exact size all the time. Documentation was top notch as were all the comments.

Juan Ruiz - Reply

2.5 hours. (0,5 hours for the difficult screw/nut step.)

Jeffrey Lazar - Reply

After completing all steps, the X-Carriage is now unable to reach the X-EndStop. No more "click" when moving the X axis to the end. Is this normal?

FranPi - Reply

Hi, see my comment to your first post. Extruder must be able to reach the endstop. Otherwise, the printer won't work.

Jakub Dolezal -

I had the same issue as Lyrandel. No matter how hard I pressed, I couldn't get the M3x20 to thread in the top left print fan hole. I eventually used the 25mm screw, which was displaced slightly during extruder mounting, so I swapped it back with a 20mm once the nut was in place. This was the only nut trap I ran into problems with (other than the square traps being a bit loose).

Daniel Packer - Reply

About 2,5 hours. I didn't have any significant problems that other people in the comments had. Either the kit quality has gone up, or maybe my thoroughness paid off for this step.

Anton Eliasson - Reply

Hi Anton, it can be both. I'm reporting all the issues during assembly and working together with my colleagues to get rid of them.

Jakub Dolezal -

I think the challenge, tedium, and frustration of securing the extruder to the X carriage (step 27) has convinced me not to get the multimaterial upgrade. I do not want to do that again.

David H. Brown - Reply

Hi David, in multi material upgrade the assembly is easier thanks to the absence of the motor, the whole Multiplexer body can be thinner resulting in shorter screws.

Jakub Dolezal -

All done, I have two M3n nuts and one M3 bolt left. Is this from the pinda change? or this thing will explode due to the missing two nuts?

Jin Young Song - Reply

Not sure about the nuts, but the third m3x30 bolt belongs in the extrusion motor. Step 9 only shows and tells you to use two, but there is a bit of wobble and three m3x30 bolts as well as three holes for the motor. Putting the third bolt in eliminates the wobble.

Jacob S. -

Hi Jin, nothing will explode :) Please go through the chapter again to ensure you followed each step. It might happen my colleagues in the production added more nuts or bolts by a mistake.

Jakub Dolezal -

Step 9 says to use two screws to mount the motor, and only shows two, but there are three holes for the motor and three M3x30 screws.

Jacob S. - Reply

Hi Jacob,

using two screws in step 9 is ok, the last hole will be used later.

Jakub Dolezal -

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