1. Needle-nose pliers for tension check.
    • Needle-nose pliers for tension check.

    • 2.5mm Allen key for M3 screws

    Add Comment

  2. WARNING: Printed parts aren't the same! There is a left and right oriented piece. See the pictures. Also note the correct orientation of the frame, the "PRUSA" logo must be facing towards you.
    • WARNING: Printed parts aren't the same! There is a left and right oriented piece. See the pictures. Also note the correct orientation of the frame, the "PRUSA" logo must be facing towards you.

    • For the following step, please prepare:

    • Z-axis-bottom-left (1x)

    • Z-axis-bottom-right (1x)

    • M3x10 screws (6x)

    • Place the printed parts next to the frame. See the picture for CORRECT ORIENTATION (the small circular openings must be facing out).

    • Tighten each printed part with M3x10 screws.

    • Don't use excessive strength during tightening! In case of increased resistance, try to place the screws from the other side to "clean up" the hole. Then return to the front side.

    There is a little bit of play in these brackets during tightening. I didn't realize it when I built my mk2s and it caused a slight misalignment. This time, I decided to use a machinist’ square here to ensure these were square with the frame. Worked great.

    Steven Underwood - Reply

    Thanks for the tip. Mine were quite misaligned until I used a square to align it.

    Andreas Sjolund -

    Thanks for the comment Steven, I had mounted my right Z-Axis motor and noticed that the leadscrew was not vertical. I took it off, squared up the top of the bracket to be at exactly 90 degrees to the frame side and it corrected the problem with the leadscrew. It would be worth adding this to the instructions. All you need is anything with a right-angle to square it up.

    Kevin Gallagher - Reply

    Thanks for the feedback guys, we will discuss a way to adjust the design to prevent misalignment.

    Jakub Dolezal - Reply

    For me a book works well to ensure the right angle to the frame.

    Martin Wolker - Reply

    The image shows an “A5” label. Mine is labeled “B1”

    Øyvind Taknæs - Reply

    Hi Øyvind, yes as the parts evolve we are changing labels on them.

    Jakub Dolezal -

    While your at it, it wouldn’t hurt to make these parts poka-yoke. They look almost identical, and I’m sure plenty of people have switched right/left during installation. Maybe make the hole pattern slightly asymmetrical.

    Mahir Abrahim - Reply


    thank you for the suggestion. I will add a warning to the text.

    Jakub Dolezal -

    Alternately, it would be a fairly trivial change just to incorporate the orientation into the version number, i.e. print B6R and B6L.

    Zachary Loafman -

    I received two of the exact same Z-axis bottom right pieces. It looks like I am missing a Z-axis bottom left. The part no. is B6

    Austin McLean - Reply

    Hi Austin, please contact our support to get the correct one (info@prusa3d.com). Thank you

    Jakub Dolezal -

    I have the same z-axis motor holders parts (B6). This will cause a problem with assembling the printer / rods.

    Any suggestions?

    Asad Hindash - Reply

    All the parts are labeled B6. Thats a version number. Just make sure the parts are opposite.

    phr0ze -

    I have the same parts / orientation for the z-axis motor holders. Any suggestions?

    Asad Hindash - Reply

    The two parts are the same direction. However, I 3D printed the wrong part. Thank you.

    Asad Hindash - Reply

    Adding to the earlier Poke-yoke suggestion, these parts could easily be made identical without sacrificing function.

    Andrew Forsberg - Reply

    Also remember that PRUSA logo faces you in the orientation! :)

    Erin Baker - Reply

    The left piece was slightly thinner than the right one.. The issue is the motor screws than touch the inner coil and make an awful grinding noise (!!) I had to use M3x8 instead, and manually turn the rod a couple times so the metal scraps would eventually clear themselves… :/

    Rudolph Sand - Reply

    A top-down photo showing the final assembly would be good here to confirm the correct parts have been installed in the right places.

    Timothy W. Skloss, Ph.D. - Reply

    I have got an issue with the vertical alignment of left motor screw, this issue reveals on the step 4, but in MHO there are two possible causes, incorrect positions of threaded holes in the vertical frame or incorrect positions of holes in the printed part, this result in the horizontal misalignment of the Z-axis-bottom-right plane and so the vertical misalignment, see picture,


    it’s hard to solve this problem, enlarging the 3mm holes in the printed part is useless because the heads of the M3x10 screws have a 6mm seat that prevent any adjustments

    you can enlarge this hole only with a flat point milling cutter, otherwise , with a classi drill point you may damage the 3mm hole

    I think that forcing the motor screw to top support is not recommended

    any suggestions?

    Guido Tognan - Reply

    Hi Guido, please contact our support at info@prusa3d.com, I think your frame needs a replacement.

    Jakub Dolezal -

    I have the exact same issue with the alignment of the left side piece.

    Dan - Reply

    Hi Dan, Hi Jakub,

    I’ve solved my issue with a Dremel like drill and a small cilindrical milling cutter (diam. 2mm, lenght 5mm) I have worked on motor holder seats of the M3x10 screws and, with a 3.25mm standard point, on the 3mm holes

    1) you enlarge 3mm holes in the motor holder with the 3.25 drill point

    2) mount the motor holder, try to rotate it slightly to the correct position and with a marker highlight the parts of motor holder seats that are in contact with the screws heads, unmount motor holder and remove with the milling cutter very small portions of seat near the marked zones

    3) mount the motor holder again and repeat step 2) until you can align correctly the motor holder

    Guido Tognan -

    Hi Guido, thanks for sharing your approach. This gave me an idea ;)

    Jakub Dolezal -

    A good addition to the instructions for this step could simply be to mention that the small hole in the brackets should be to the outside of the frame

    Ben V - Reply

    Z axis frame need a shallow socket for motor holder doing alignment, or change the orientation of screw for making adjustment easier

    Hsiung - Reply

    If you have any trouble with this step, I find that placing the frame down over the ledge of a table or desk helps because it makes the whole thing horizontal and flat.

    Zerg620 - Reply

    +1 to Erin Baker- I got the motors on the left and right side, but I had the whole unit turned backwards at the time. Since I have not seen the machine built yet, it is not obvious which is the front.

    Graham Entwistle - Reply

    Hi Graham, thanks for the feedback. Instructions updated with the frame orientation ;)

    Jakub Dolezal -

    Z-Axis-Bottom-Left and Z-Axis-Bottom-Right have changed.

    I have version B7, which has slots instead of the small round holes. Here’s a photo: https://i.imgur.com/005KVwk.jpg

    The packaging also calls them both Z-Axis-Bottom, when I guess they should be Z-Axis-Bottom-Left and Z-Axis-Bottom-Right.

    Just in case anyone gets confused until the documentation gets updated

    Alfie Day - Reply

    I have a B7 version, which are both the same so there is no left or right side!

    How to deal with this problem?

    pic 1

    pic 2

    pic 3

    did I got 1 wrong bottom? or can it still be used?

    Peter - Reply

    • For the following step, please prepare:

    • Z-axis motor (2x)

    • Note each Z-axis motor has different cable length. The shorter one must be on the left side, longer on the right side.

    • Z-screw-cover (2x)

    • Remove the trapezoidal nuts from the motors. DON'T THROW them away, you will need them!

    • Screw the Z-screw covers onto both leadscrews.

    • Covers should be screwed fully to the motor, but not too tight! The motor must be able to spin freely!

    My fingers hurt so bad :) … these were so tight it almost made me believe I created the threads as I was turning the leadscrew :) … I would have designed some tabs like those of a wingnut but shorter, 4-5mm deep to be able to grip the covers better. My 2c :)

    Florian Ford - Reply

    There are 2 extra components here that I have and have not found them in the manual. They are black printed cones shaped things that are loose. I have just scrolled down a bit on this page and see something like them at the end of the lead screws near the motor. Is this them? If so this is a big pain as I have my axes assembled and now need to disassemble them to put these on. Note they were supplied loose in my kit with no instruction as to what to do with them.

    Stephen - Reply

    Hi Stephen, check the second picture, those are called Z-screw-cover.

    Jakub Dolezal -

    Ah - apologies - I have now looked properly and see where they are mentioned above. My mistake :(

    Stephen - Reply

    No problem ;)

    Jakub Dolezal -

    Could you add a picture showing what “trapezoid nuts” are? Step 4 doesn’t use them and I don’t know what’s meant by this.

    Peter Larsen - Reply

    Using the pliers to get the z-screw covers started saved this process, it seemed impossible to get thems started by hand.

    Sean - Reply

    I have one Z-Screw cover that went on easy, and one Z-Screw cover that I had a very difficult time with even using pliers.

    Paul Bowers - Reply

    Very tough on the fingers, one was easy and the other nearly impossible. Better QC needed here. Also a better description of the covers might help to identify them. I didn’t know until today what a trapezoidal lead screw and nut were.. and I ‘ve only been a (poor) engineer for 50 years….

    Alex Geller - Reply

    For me it helped to push straight down (not too hard) and then start turning. I couldn’t thread them like a nut like I did with my MK2.

    James Becwar - Reply

    The photos of the Z-screw covers screwed down against the motors are visible only after knowing what to look for. The black on black makes everything blend in. I got them to screw down pretty easily .. I rotated them in a counter-clockwise direction first before screwing them on. That seemed to align everything.

    Edward Traxler - Reply

    A photo showing what the “trapezoid nuts” are (especially since they’re not very trapezoidal) would make this step much more clear. The screw covers are identified in the second photo, but there is truly no label for the trap nuts, the term just shows up in the text.

    Kalani - Reply

    Hi Kalani, thanks for the feedback, I’ve circled the nuts and will think of some update to this step. We call them trapezoid not because of their shape, but because of the function (they move on the trapezoidal rods).

    Jakub Dolezal -

    Once started it is surprisingly easier to turn the screw and hold the cover in place to work its way down.

    Rich - Reply

    Agreed - Turn the threaded rod and hold the z-screw cover steady. Much easier.

    Corey Dangel -

    more accurately

    1. place the motor base on your lap with the rod pointing up

    2. use one hand to hold the z-screw cover and apply a little downward pressure. This way you aren’t grabbing the fine edge of the z-screw but, rather, the flat tapered surface.

    3. turn the threaded rod with the other hand and the screw cover should glide down, easy peasy

    Corey Dangel -

    Thumbs up for Corey Dangel’s 3 steps.

    I found it helpful to initially rotate the threaded rod in the “wrong” direction until I here a “click” when the 4 little “teeth” on the inside of the “Z-screw-cover” “fall” of the edge of the tread.

    This positions the “teeth” just in place to start the threading.

    Then change the rod’s turning direction so the “Z-screw-cover” enters the tread.

    Eyal Peleg -

    Worked like a charm, thanks:)

    Tor Andre -

    although it is possible to see in the photo for step 4 it would be nice to have a comment saying that the “trapezoid nuts” should be mounted with the flat side towards the motor.

    Eyal Peleg - Reply

    O.k. thought I have an “Edit” link for my own comment, If I try to actually post an edit it says that “You cannot edit comments after five minutes have passed. “ so where I wrote “trapezoid nuts” it should be “Z-screw-covers”.

    Eyal Peleg -

    I’ve been assembling while wearing Nitrile gloves (I hate fingerprints all over everything - reeks of bad quality) because I couldn’t find any cotton ones.

    The Nitrile gloves made this step trivially easy … except when I needed to back-out a Z-screw-cover that was a bit too tight against a motor. There is just nothing to grip on these parts!

    Redesign recommendation: add two (or 4) short raised ridges to the cones for gripping, or even a single hole so that the smallest Allen key can be inserted. I think the raised ridges would be better.

    I almost resorted to drilling a hole, but got lucky and managed to moved the troublesome Z-screw-cover away from the motor a bit.

    Andrew E. Mileski - Reply

    Could you please put these on at the factory? I’m sure you could make yourself a tool that quickly and easily installs them. We all enjoy putting together kits but this was a rather tedious step.

    Timothy W. Skloss, Ph.D. - Reply

    OMG agreed, worst part!

    Mike -

    This is one of the parts where you think: “To mess with you that you wanted to be a cheapskate - and not buying the assembled version - we mount one piece on a rod that doesn’t belong there and make you mount another much harder piece to mount on it, instead.” Ok, message received! ;-)

    patrick.fehr@fbc.ch - Reply

    I tip for unscrewing the trapezoidal nuts: try to use as much skin as possible. Instead of unscrewing with just your fingers, use your hand or your arm. What might take minutes takes just a few moments with your whole arm.

    Zerg620 - Reply

    If you screw on the Z screw covers too tight, grip the Z screw cover and rotate the Z-axis screw clockwise (to the right as if you were tightening it.) That will move it away from the motor.

    Zerg620 - Reply

    I recommend holding the Z screw cover in one hand while you twirl the lead screw with the other hand. Much easier than twisting the cover onto a static lead screw.

    Julien - Reply

    I found that the z screw covers would not move at all; until I carried out a “fettling excercise” which reduced the effective inside diameter of the four small lugs which engage the leadscrew thread. Lumps on the outside of the cone would be beneficial.

    Julians method of applying downward pressure on the nut whilst turning the leadscrew with the other hand worked well for me.

    Harking back to earlier comment: The confusing “trapizoidal nut” should be called what it is: The leadscrew (drive) nut, which also describes what it does.

    Les Grosvenor - Reply

    I don’t think I did anything wrong, but this was no big deal. Of course I screwed the screw onto the cover, not the other way around (I turned the screw). If this was an assembly line, I could see them creating a power plug to turn the motor, but it really wasn’t bad.

    Robert Eden - Reply

    A “parts required” picture for this step would be really useful. Careful as I (thought I) was, I missed the Z-screw cover until I had the printer completely assembled.

    Also, the covers were VERY difficult to get started — some re-engineering seems to be called for.

    Keith Spitz - Reply

    These covers need to be tight to fulfill their function but we will also double check how much of a tolerance this part has. Thanks for the suggestion!

    Martin Lexa -

    Trapezoidal nuts screwed off easily, motor covers screwed on easily. May have just gotten lucky.

    Matt Laudato - Reply

    This was the step that I was most worried about. Everyone said this is the worst part!

    Went on easy for me too, maybe they have updated the printed parts?

    Andrew Holloway -

    • For the following step, please prepare:

    • Z motor left (labeled Z axis left, shorter cable)

    • Z motor right (labeled Z axis right, longer cable)

    • M3x10 screw (8x)

    • See the second picture. The motor with the shorter cable (red arrow) is on the left, the motor with the longer cable (orange arrow) is on the right!

    • Motor cables must be oriented towards the frame, there is a small cutout in the frame on the lower edge for each cable.

    • Secure each motor with four M3x10 screws. Tighten evenly and carefully as you might break the printed parts.

    Could you add a photo specifically showing the wire exit/orientation of the motors? Thanks!

    Kenneth Albanowski - Reply

    Agreed or just state the wires exit at the rear and route downwards in the slot used for the bottom fixing screw of the bracket.

    Neale Brodie - Reply

    Kenneth (@kalbanowski) and Neale (@jnb), thanks for the feedback, step will be updated. Motor wires must be facing the frame and there is a cut out for them on the lower edge of the frame.

    Jakub Dolezal - Reply

    Motor wires must be facing the frame and there is a cut out for them on the lower edge of the frame.

    A suggestion: replace facing the frame with facing the “XY Frame” or the “verticle frame” , to clarify they should be facing it and not facing the aluminum extrusions, which may appear to be "frame” to us laypersons at this stage due to the amount of assembly completed already :)

    tim -

    To get the threaded rods quite center instead of having them to force into the top ends later it’s not a bad idea to check the alignment of the threaded rod with the two holes at the top of the frame before screwing the motor to the z-axis holders. I had to loosen the holders again and push them a bit while screwing them to the frame to get the threaded rods to be quite straight.

    Uli Braun - Reply

    Did as Uli to get the threaded rods straight. Just fasten the motor holder to the frame so that could be moved before mounted the motors. Then adjust the shaft in the middle of the two holes on top. Then removed the motors and and tighten the motor holder.

    I also had some problem with the one of the threaded rods was leaning away from the frame, it diffed about 3 mm from bottom to top. It looks like the holder is not 90 degrees. I ended up to put washers between the motor and the motor holder (0,8 mm thick) to tilt the rod to the farm. The glue stick that comes with the printer works perfect to compere the distends between the frame and the threaded rod.

    Mattias - Reply

    At least for the B6 version of the part, if the bottom screw isn’t in all the way then there isn’t enough of a cut-out for the wires. This results in the threaded rod not being straight, but much worse it can crimp the motor wire. (I’ll have to wait until I complete assembly to see if this damaged the wire or just bent the insulation.)

    Erik Nygren - Reply

    would it not been better to have the wires go through a hole i the frame instead of a cutout in the base of the frame? (so that you can never place the frame on the wires?

    Eyal Peleg - Reply

    Had to use M3x8 screws on the left motor, because the screws were touching the motor coil :/

    If it happens, just remove the screws, turn the motor shaft/rod a couple times, and the grinding noise should go away…

    Right motor is fine with M3x10 screws…

    Rudolph Sand - Reply

    How critical is it that the threaded rods are vertical? Mine aren’t, but I see only two comments about it, and nothing in the instructions.

    Richard Chipperfield - Reply

    • For the following step, please prepare:

    • Trapezoidal nut (2x)

    • M3x10 screw (4x) or M3x18 screw (4x)

    • Starting X-end version B6 you need longer screws M3x18. In the first batches (February 2018) the screws are in a separate bag.

    • M3n nut (4x)

    • Turn the X-axis upside down and insert nuts into traps on both X-ends.

    • In case you can't press the nuts in, don't use excessive force. First, check that there isn't any obstacle in the nut trap.

    • Note: Design of your X-end printed parts might slightly differ, but the assembly process is the same.

    First, check that there isn't any obstacle in the nut trap.

    Keith Manley - Reply

    Hi Keith, sentence rephrased, thank you.

    Jakub Dolezal -

    Why no thread lock! :P

    Mr Cookie - Reply

    This step has really turned into my first roadblock. The nut just won’t settle far enough into the trap on the left side for the screw threads to catch. I’ve used a pick looking for any obstacle and just don’t find one. Does anyone have a good tool/technique to ream it out an extra millimeter?

    Rueben Nilsson - Reply

    … Nut trap :D

    H4irBear - Reply

    I cannot get the nuts to fall in the trap correctly no matter what I do. This entire process has been incredibly frustrating.

    Sean - Reply

    Pliers to the rescue again. I had to force the nut down in to the trap with the plies by putting an uncomfortable amount of pressure on the nut. Ended up working, however.

    Sean -

    I’m also having difficulty getting the nut seated correctly into the trap. Printed part version B6.

    Paul Bowers - Reply

    I got super worried that I would need to use some pliers or something to cut some of the stuff in the nut trap, since the nut did not wanted to get in deep enough.

    However, I found the trick, after 1h of random tool testing :)

    Tweezers, pliers, allen keys to align from the screw hole and kaboom.

    The trick was to not use a lot of force or anything, but to bruteforce the exact rotation of the nut so that it can fit.

    Lyubomir - Reply

    Thank you! This worked for me as well. I would assume that the problem for most of the printed parts (my part being B6) is not that there is something blocking the nut from being inserted but the need to force the nut in the right position. I needed to force the nut into position for the outside holder also so it makes sense that I would need to do the same for the inside.

    Robert Contreras -

    Wow! I’m impressed with Lyubomir’s method. Last night I had a terrible time trying to slide-in the left nut. I could see no obstacles - I used a bright flashlight to light the interior of the part - and I dug around a little with a hobby knife and an embroidery needle with no results. This morning I read Lyubomir’s method and it worked great! I screwed the nut onto the end of the 18mm screw, to have something to hang onto, then laid the nut into its channel - importantly, with the point, not the face, facing out - then held the nut in place as I unscrewed the screw, so the nut would move into place. I then used the tips of the needlenose pliers to push the nut home. It still didn’t sit perfectly, but the screw then successfully went in.

    A design suggestion: increase the clearance above this nut 1-2mm so that if the hole has rounded edges (which I suspect is the problem) the nut can sit above those rounded edges, then be pulled into place when you tighten the screw.

    Brad Needham -

    The deep-set trap on these parts had me stumped and worried for a bit, but then I found a method that worked for me: just shove the nut in as far as it reasonably goes, and then insert the second-smallest hex wrench into the screw hole, just push it into the nut. It’s smaller than the screw, it goes pretty easy. The. Just push the nut in place with the key, and it popped right in, no problem.

    Maybe I just got lucky (twice), otherwise this might work for others.

    Kalani - Reply

    Thank you all for the “align with allen key/ hex wrench” tip!

    Jeff Spencer - Reply

    Would be helpful if you explicitly called out the orientation of the nut in the trap - I.e., a corner of the nut faces out. Can almost see that in pictures..

    Rich - Reply

    Hi Rich, the orientation is given with the shape of the opening.

    Jakub Dolezal -

    OK this was extremely frustrating. Those nuts really didn't want to go al the way in, not even with the tricks mentioned here. In the end I resorted to using a dremel to enlarge the hole. But because of the awkward angle the hole was now too big to actually trap the nut. But with pliers holding the nut in place I was able to make things work. But boy did I so _not_ enjoy this part!

    Tako Schotanus - Reply

    The slotted nut trap on the left of the assembly allowed the nut to rotate when the screw was inserted. This meant that it was very difficult to tighten one of the screws holding the trapezoidal nut in place - this I suspect is crucial to accurate Z axis layering. I had to put pressure on the nut with the tips of the pliers to stop it rotating and slowly advance and back-off the screw until it was seated. It’s still not as tight as the others and I’m worries. I think a square nut would have been better than a hex nut in this slotted trap, but the instructions clearly state a hex nut.

    Jonathan Butters - Reply

    I have the same issue as Jonathon, but I haven’t been able to salvage it. Now, every time I try, it gets worse. I’ve just tightened up the one as much as I can and I’ll probably reprint the part, but pause as the trap is finished and put the nut in place.

    A better production solution might be to move the trap down a bit so it doesn’t sit inside the hole for the nut, and use a longer screw to reach it.

    John Jones - Reply

    This step might be better moved to before the rods are inserted during X-Axis assembly. As others have noted, getting the nut properly positioned in the slot is problematic and I’m constantly worried about the possibility of warping the rods while trying to get this part done.

    Raymond Toovey - Reply

    Hi Raymond, thanks for the suggestion. I was thinking of a solution, but to my opinion it will bring more confusion and even more explanation. You need to take first the Z-axis motors, remove the nuts and then use them on the X-axis. Take an Allen key and check first, whether the nut trap isn't filled with some particles.

    Jakub Dolezal -

    I agree with Raymomd. The nuts can be inserted before smooth rods are introduced in X-axis assembly. No need to handle Z motors or remove nuts off them. Jus insert M3 and pre-install bolts to ensure proper alignment while doing the X. Many nuts are pre-inserted throughout the build.

    Also redesigning the parts to use square nuts on the tricky ends might be the way to go. Hex nut is way too fiddly to install the proper way back there.

    Marek Stenky -

    I’m afraid I have to disagree with Mr. Dolezal on the idea that making this solution part of the official guide would be more confusing. This is infuriating, and if this step had been earlier in the process, where we were only handling a single part, it would have been considerably less complicated. As a complete novice, I have gone through this entire process without knowing what part comes next, so the idea that we’d place a series of parts together that wouldn’t be dealt with again until many segments further on would in no way increase my confusion in the slightest.

    Daniel Kilboy -

    This is total crap. No matter how I position the nuts in the slots there just isn’t a position that works. I’ve wasted a f’ing hour just on this step. The slot is round so have the nut with one of the hex points poking out just moves the screw thread further out of the hole.

    I’m bitterly disappointed having to wait two months and be faced with this crap.

    Stephen York - Reply

    Hi Stephen, I'm sorry for the issues, in case you won't be able to place the nut in, please contact our support.

    Jakub Dolezal -

    Very difficult. I got this done but the slot needs a redesign for sure. I’d suggest the square nuts would be better so there could be more clearance without compromising the function.

    Tom Fountain - Reply

    Hi Tim, thanks for the suggestion. I will discuss it with the devs.

    Jakub Dolezal -

    After two days I still can't get this nut into this slot. I've tried every suggestion here except for making the slot bigger and the nut still doesn't sit correctly. It doesn't help that it's impossible to see the slot with the black printed. I whole heartedly agree this slot needs some kind of rework.

    Ryan Latimer - Reply

    Hi Ryan, in case the slot is somehow distorted, please talk to our support team about getting new parts.

    Jakub Dolezal -

    I did end up getting the nut in. I had to go into the screw hole with a pick at a sharp angle to get inside the nut and then pull the nut into the slot and hold it down with the pliers while I tightened the screw.

    Ryan Latimer -

    Running into the same issue that everyone here has, my kit has B6 printed parts. I spent over an hour trying to force the nut in. I’ve tried almost every suggestion here other than using a dremel to create more space. There’s no debris in the holes. I’m unable to insert it part way and use a smaller hex wrench to shimmy it into place.

    This isn’t even my first issue. The holes for the aluminum extrusions and steel plates for the Y-axis required large effort to get them to all fit nicely. Also could not successfully get my Y-axis perfectly level. Not thrilled with this kit so far.

    Mike - Reply

    I filed down the nuts on one side and was able to get this in.

    Mike -

    I solve the issue by grind down(using dremel) two opposite corner(just a bit) of each hex nut. It will fit the slot perfectly. You can use a long needle to guide the nuts into the slot and turn it to fit. It took me few minutes to complete step 5.

    W Lai - Reply

    I echo all the others who have complained that the slotted nut capture design is extremely hard to use. First, it was hard just to get the nut to enter the slot at all due to the shielding afforded by the cylinder. Then, what I discovered was that - although the nut seemed to be very loose and floating - it actually required a HUGE amount of force to push it into the proper position. Lost an hour on this one step.

    Jay Sinnett - Reply

    What worked for me here was using the pliers to push the nut into the trap. So stick the pliers down into the hole between the two nuts, then pull the handles apart to push the nut into the trap. After that look in from the bottom to see the alignment of the nut. If you can see a good portion of the nut from the bottom, then you can use the small allen key to center it a bit more.

    Also, when i was manipulating the x-axis the square nuts from the extruder housing kept falling out. I agree with others that it would be better to move this step to during the x-axis assembly. It’s not that confusing to have to take out the z motors a phase or two early.

    Adam Sbeglia - Reply

    After spending an hour looking at all the solutions and trying a few of the less brutal ones, I tried your method and it worked perfectly! Many thanks!

    Jim Lehman -

    I was unable to directly use R2 revision x-end parts I had printed myself in E3D EDGE due to this issue. (These parts are printed on an MK2 at recommended .2 layer height with PrusaControl, and generally seem to be of excellent quality.)

    Combining all of the above suggestions (allen key to pull the inner nut into alignment with the trap, and pliers to apply pressure while putting in the screw) worked, but then the hex nuts simply spun in place once the screw caught.

    I ‘fixed’ this with some 2-part epoxy dripped into the open side of the nut trap while a screw was already inserted (to keep the threads clear). This appears to have worked without side-effects and I was able to back the screws out with minimal effort. I haven’t reassembled the entire axis yet, but it feels like it’ll hold at least through one assembly.

    I wonder if the EDGE is slightly softer than the Prusa PET and the trap edges round off just that little bit more easily. In any case, this part seems to need some redesign if it is this fussy.

    Kenneth Albanowski - Reply

    I was using the supplied manual to do this step and the image of the nut trap on the left part it was not clear to me that a round nut was needed because all the previous insertion slots were for a square nut. So I inserted a square nut and screwed into it but it wouldn’t get all the way in and then I couldn’t get the nut or the screw out. With the help of a friend I was finally able to get it out and the correct nut and screw in. This cost me two days of stress and searching. I really thought I had screwed up the whole printer.

    I think if you are going to switch the type of nut you are going to put in a slot you should highlight the fact. I admit that if I had been following this document instead of the printed manual I wouldn’t have made this mistake.

    gritty - Reply

    Hi Gritty,

    thanks for the suggestion, I understand your point. The nut type is specified in the description and there is also a picture. I will see if I can do more to highlight the correct nut.

    Jakub Dolezal -

    I also had issues getting the inner most nuts into the traps. I tried the suggestions of trying to guide them in with the allen keys and pliers, but I could never get them seated in far enough.

    I found another trick that may help someone else. I noticed that a 3/8” socket extension bar was almost a perfect fit to place into the x-ends’ shafts. This allowed me to gently rotate/wiggle the extension bar around and coax the nut in correctly. Since the extension fills the entire shaft it puts even pressure on the printed part so I was applying much less pressure/stress than trying to force the nut in with the allen key or pliars.

    James Shumpert - Reply

    I also had issues with this step, particularly the left X axis inside trapezoidal nut. It’s probably human nature to put the easier nut in place first. I realized that if I removed the outer nut, I had a clear path to push the inner nut into place with the screwdriver. I was able to apply sufficient force to the nut to drive it home. Once the inner nut was placed, I was able to then place the outer nut again easily.

    Duane Pinkerton - Reply

    here’s what worked for me to get the nut seated into the hex opening - I screwed the nut onto the end of a screw and then used the screw as a handle to push the nut straight down into the hole.

    jodi buckley - Reply

    Righto, I received my kit a few days ago and I’m now a few hours into this assembly and no great problems so far [apart from receiving a VERY dark shade of orange mouldings; so dark in fact that even a blind man would say that they were BLACK!] . . . . . anyhoo, this stage has quite a few comments compared to previously!

    I’m on B6 mouldings like a lot of others and with my (very) nearly 60 year-old eyes I’m struggling to see from the recesses in the moulding which way the hex nuts should be orientated - it appears that a correctly inserted nut should present a corner in the middle of the recess (ie the nut needs to go corner first NOT flat first!)

    So what worked for me is this:

    I gently pushed a nut into the opening and then using an engineers scribe (of about 1.5mm diam but VERY pointy!) from underneath through the screw hole, I located the hole in the nut and physically moved it into place - 2 minutes all sorted and for what it’s worth, my heart goes out to all those who have suffered snags with this stage!

    Mark Baker - Reply

    I managed to get the nut cross-threaded on the bolt and now it’s turning in the slot. Remains to be seen whether I can get the nut and bolt out at all, and if I can, whether the slot will be ruined and useless. This is not a good design. Perhaps a square slot and square nut would make insertion easier and grip more reliable?

    Anne - Reply

    As everyone here has noted, this is a difficult step. We tried most of the options described here; what finally worked for us was holding the nut in place using a needle ( we didn’t get close enough for the small Allen key), and then tapping with a light hammer and using one of the larger Allen keys as a drift.

    I can’t say I recommend this technique, but it worked pretty well for us.

    One thing to note is that you don’t have to get the nut absolutely central, mostly there is enough for the m3x18 to get a grip.

    There was some discussion about moving this step earlier in the assembly. I think it does make sense to do the nut trap insertion earlier, even if the trapezoid nuts aren’t discussed. The previous stage includes 6 other nut trap insertions, two of which aren’t even held in place, so why not this one when the x-axis end pieces are a little more accessible.

    Gordon - Reply

    You absolutely should have this step sooner when it is easier to manipulate the poorly designed pieces. I ruined one of them after spending almost an hour scraping out bit and pieces of plastic. The slot is stripped. I can’t get the bolt out and I can’t tighten it. Why is it on this step you suddenly stopped adding warnings?! At this point, I guess I need to download the STL for this part so I can waste another hour on it.

    James Lewis - Reply

    Hi James, I'm sorry for your experience. You can either download the STL or contact our support at info@prusa3d.com

    Jakub Dolezal -

    If you’re having trouble getting the M3n hex nuts in the trap, try using one of the allen wrenches; insert the long end of the wrench in through the bottom (where the screw will go, try to get the wrench end through the M3n hex nut and pry it forward toward the inside end of the trap (using the allen wrench to get leverage and sorta pry it into place).

    blueyes13@gmail.com - Reply

    Would probably be better off if you designed the parts two inner nut holders for the four sided square nuts

    FlashGorden - Reply

    There is a slot/cutout in the outer circular portion of the X-axis which holds one of the nuts. Use that slot to place the shaft of the screw driver with the blade portion of the screw driver against the problematic nut which has already been placed in it’s slot. Use a small hammer against the handle of the screw driver to drive the nut further into it’s slot. Hex wrenches can be used as a further drift to align the nut as mentioned by others. Caution: the unsecured square nuts previously placed in the bearing carrier are likely to come out and need reinserting.

    Gary Shumway - Reply

    Ok so as a lot of people have had issues with these M3n nuts I did file down just slightly one of the corners (The one that will go the farthest into the piece) Once I did this the nut went in. I would not recommend filing more than one as it may spin in the hole.

    For Prusa if they don’t want to change the nut used or remodel the pieces, I would at least give the back corner a little more space do to tolerance issues with the printers.

    Kris Sovers - Reply

    Hi Kris, Prusa is already working on a fix ;)

    Jakub Dolezal -

    I couldn’t get the nuts in. In the end I used a soldering iron to heat them up, and pressed them in with a pair of pliers while they were hot.

    Andreas Tarandi - Reply

    After two hours of fiddling, this step is done. Agree with what others said. Ended up using the needle nose to hold the nut at a corner, carefully insert the nut into the hole with left and right sides parallel and vertical, enough pressure on the nut to push it in a bit and then a considerable amount of force on the small hex wrench to pull it the rest of the way.

    A royal pain in the patooty.

    Brenda Bell - Reply

    Unfortunately I had suffered real pain with this step, nuts did not go in in any orientation, they were almost 1mm too shallow. Drilling didn’t help and I was considering contacting Prusa to get a different piece, this part obviously didn’t print correctly. The outer nuts also didn’t go in, had to use a knife to enlarge the hole.

    But the inner nut hole is impossible to reach with anything but a driller, so I used a soldering gun in the end to enlarge and deepen the holes. It did work out in the end but it was not easy at all, it was very difficult to make the hole level and straight, so the nut could also stay perpendicular to the screw.

    2 hours wasted, please redesign this part or improve quality control.

    thanks a mill

    Jan Záruba - Reply

    Hi Jan, I'm aware of the issues you guys posted here. This parts will get a redesign soon. In the mean time I will ask our post processing department to check these slots/traps more carefully.

    Jakub Dolezal -

    I don’t have anything new to say here, but wanted to reinforce that this step is extremely frustrating. It was the first time during the build that I had to resort to curse words. I ended up pulling the STL to make sure that hex nuts were actually intended rather than square nuts. There was enough vertical slop in the hole to allow the nut to sit at an angle, and the screw got cross-threaded. The nut spun through the plastic trap, and I couldn’t go either in or out with the screw. Eventually, I held the nut with needle nose pliers and my wife was able to remove the screw.

    Harold Toler - Reply

    It took me approximately 8 hours to complete this step. I actually “invented” and tried all of the techniques on my own (cleaning, Allen key, pliers, screwdriver, socket), save for physically altering the part or heating the nut.

    The first captured M3n nut took roughly 3 hours to position. It eventually slid into place after hours of manipulating it with the smallest Allen key. It was quite a sudden surprise.

    The second M3n nut took about 5 hours to position. I repeatedly got it 98% into position, and 99% with further manipulation, but just not enough for the M3x18 to engage it.

    After a nice cup of tea, I tried again, and managed to get the second M3n nut 99.5% into position. This was enough for the M3x18 to engage, but I was very concerned about cross-threading. I took it slowly, repeatedly advancing the M3x18 slightly then backing-out completely and re-attempting (the goal being to properly seat the M3n nut). Eventually it worked.

    My index finger now has a blister from excessive Allen key twiddling.

    Andrew E. Mileski - Reply

    I tried multiple techniques but ended up using the pliers to push the nut in further. On one side I kinda had to lay them over the nut and on the other I just to push it in with the tips. Definitely the worst step so far (by far).

    Tim S - Reply

    I was breezing through the build until I got to this step. I can’t get the nut in far enough for the screws. So I resorted to using a Dremel to shave 0.5mm off the sides of the nut to get it into alignment for the screw.

    Patrick - Reply

    Please redesign the printed parts so that this step goes smoother! It took a LONG time to complete this step. I have version B6 for both printed ends. The nuts were very hard to put into place and I had to improvise tools to force them where they needed to go. The holes for the M3 screws are printed too small which can lead to CROSSTHREADING in the nuts. This happens because the screws form threads in the plastic as they are screwed in, and when the screw meets the nut the threads in the nut most likely won’t match the threads formed in the plastic. To avoid this I drilled out all the bolt holes with a 3mm drill and then assembly went much smoother.

    Timothy W. Skloss, Ph.D. - Reply

    This worked for me:

    Remove the hex nut from the outer nut well

    Place a hex nut in the inner slot, oriented with a corner facing out

    Take the 3mm allen key, while holding the long end place the tip of the short end on the corner of the hex nut so that the shaft of the allen key aligns up thru the outer nut well.

    Tap on the 90deg bend of the allen key using the supplied red handle screw driver to drive the inner hex nut deeper into the nut slot

    John K - Reply

    i am stuck at this part as i can only get 1 screw into each trapezoid nut.is it ok if i continued the assembly with only one screw inserted?

    khong - Reply

    Hi there,

    Most likely it will be fine. Yet you might face some problems in the future :(

    Tomáš -

    Same issue as others. Managed to get it almost aligned with a tapered pointed spike from a set of O-ring pick/hook set (about 3mm dia.). Then ran a 3mm tap through the plastic & nut .. removed almost nothing but enough to get the screw in without further issue.

    This is my second Prusa kit, and I think the toolkit should include a 3mm tap to clean out threads where necessary.

    Brian Knight - Reply

    Alright, after put it in and taking it out a few times I figured out a good little tip. Looking at a trapazoidal nut you can see how each side of the nut has two parallel flat sides. This is the narrowest part of the nut. You want to guide the nut down the channel and keep those flat sides against the walls. It is going to try to rotate and that is what makes it feel tight. Just keep those flat sides against the walls as it slides down.

    EJ Mason - Reply

    ok, maybe i’m wrong, but to me it looks like instead of 4 M3n nuts, it looks like 2 M3n nuts and 2 M3nS nuts. It looks like the square nuts go inside the pieces. Am I wrong here?

    Darrell Dudics - Reply

    I would suggest a warning about losing the M3n nuts for the X-carriage when you are rotating the a-axis assembly around (the ones you install in Step 11 X-carriage preassembly of the 3. X-axis assembly). I found a loose M3n nut and luckily I was able to spot where it was missing.

    Jason - Reply

    Like others, I had a terrible time getting the nut into the nut trap… until I noticed that in the photo the *point* - rather than the *side* of the nut faces out of the nut trap. This orientation is slightly different than the orientation of the other nut in the part.

    Brad Needham - Reply

    like the others said, two of the nut traps were a pain in the butt to deal with. I’ve got the R2 version printed by myself on the Mk2

    Eric Davies - Reply

    For anyone having trouble with putting nut in trap: I use a hair clip stick into screw hole and rotate it, the nut will be pulled into the trap.

    Hsiung - Reply

    If you find Alan key is still too big, this can be helpful

    Hsiung -

    Had the same problems. With the supplied B6 and the self-printed R2 parts (latest ones mid August). Had to grind down two hex nuts on two sides to get it in. A square nut design with sufficient space would help A LOT.

    Steffen - Reply

    B6 parts here, no issue with insertion of nuts. My sympathies to those with issues. Perhaps they made changes to the parts with all the previous issues and enlarged the holes.

    JBFLA - Reply

    Putting those two nuts in the corners on B6 parts sucks. I had to line them up and press them in place using the tip of a screwdriver. Took a long time too.

    Derrick Smith - Reply

    Hi there Derrick, thank you for your feedback.

    Tomáš -

    If you place the hex nots into the slot traps by hand then use the small allen key inserted into the screw hole and throught the thread of the hex nut then you can pull the nuts into place fairly easily.

    Don Bone - Reply

    Crap I cross threaded mine! Be very careful with this step! I cross threaded the inner nut. And have no way of getting it out because it spins almost freely. Thinking about jamming some needles in it to secure the nut. Any tips?

    Daniel Verstegen - Reply

    Hi there Daniel, please make 100% sure that everything is held nicely. Otherwise, you might face calibration or print quality issues in the future.


    Tomáš -

    There is no way to get everything 100% anymore. The inner nut is trapped and I can not get it out, because it spins freely. I have tried to get it out while applying some counter rotational force on the nut but I can’t get enough of a lever. All I can do now is hope the other nut and bolt hold it securely enough. This step should definitely be revised. And at least use a square nut instead of a hex.

    Daniel Verstegen -

    Same here Dan, This is a horror.

    I used the smallest hex tool in between the edge of the nut and the plastic housing to wedge the nut. on the side of the direction of rotation so that the rotating nut then wedges up tight against the plastic as you undo it.

    Julian -

    ps throw away the screw that cross threaded. it will probably be damaged and do it again.

    replace from the very convenient spares pack. thank you Prusa.

    Julian -

    Hi there Daniel, then please contact our live chat at shop.prusa3d.com. We will replace this part so that you can properly use your 3D printer.


    Tomáš -

    Many thanks for all the useful comments for this step. In the end it saved me a lot of time.  Initially, like lots of other commenters, I had trouble getting the inner nuts far enough into the traps. The  only thing that took time was in trying to decide which “successful” comment to try first. In the end I decided to use my Dremel to round off one corner of each of the inner nuts and insert the nut into the trap with the rounded corner furthest away from the opening. Maybe I got lucky but this worked fine and I had no further problem attaching the trapezoidal nuts.

    David Day - Reply

    Thanks to all. This is obviously problem for many and I think needs more design work.

    Prusa Mech. Eng. please consider changing the hex nut for the inner nut traps to a square M3nS. VMT Juian

    Julian - Reply

    Hi Julian, reworked version (B7) is in the final stage of testing. Should be released soon.

    Jakub Dolezal -

    It is fortunate for me that I picked up on a comment within the X-Axis notes concerning these nuts.; and read forward to this point; not wishing to wrestle with such a problem with the bars in the way, as many other have done.

    Initially, I too was caught out by expecting to use a square nut; but, even when the correct hex nut was tried it would not fit either.

    I too had time consuming trouble; and, despite using a strong light and magnifier, could not see precisely where the problem lay. Some of the extreme measures ( Dremel grinder, and Hot iron) used by others were considered.

    continued in next posting

    Les Grosvenor - Reply

    Continued from previous:

    However, with a last desperate effort, and positioning the nut with fine cranked teezers; then applying VERY firm pressure with the blade of a small screw driver; the nut seated correctly with a loud click; the second went in more easly, my having sussed the correct positioning, and the significant force needed.

    I endorse the views of those who say that this step should be done as a part of the X-Axis assembly, and that a square pocket would be better for consistency.

    I have not experienced square nuts falling out,as reported, but a simple solution to avoid the “ wandering loose nut “ would be to secure them in place with a small blob of blu tack or similar.

    Les Grosvenor - Reply

    This is my second Prusa kit I have purchased. The first being the MK2s. I just bought my MK3 on October 27th 2018.

    The hexagonal nuts do not fit on either side. There is no foreign matter in the traps either. Simply put, the traps weren’t printed deep enough.

    After having reported this to Prusa’s tech department’s Alberto Lopez, he kept saying , “Push it in with something. It should fit”. I told him that he wasn’t helping solve the problem by telling me “it should fit”. As a jet engine technician, I believe I know a thing or two about fits and clearances, and these nuts will not fit without modification. Alberto kept insisting and refused to send me replacement parts unless parts break. I wasn’t happy. Still not happy. Expected better service from Prusa.

    Michele Palmieri - Reply

    • Carefully rotate the X-axis onto its backside.

    • Insert the trapezoidal nuts to each X-end.

    • Note the correct orientation of the trapezoidal motor nuts!

    • Tighten the nuts with M3x10 screws or with M3x18 screws. Longer screws are needed in case of X-end version B6 and newer.

    • You can use any of all four holes on the trapezoidal nuts.

    • Note: Design of your X-end printed parts might slightly differ, but the assembly process is the same.

    Here should be the indication that the outer edges should coincide, otherwise the trapezoidal rods will later touch the upper guide which leads to rattling

    Gerhard Kunz - Reply

    The nuts that hold these screws in place fell out really easily for me. Perhaps this stage should be done earlier? when you have both of the axis ends still off the rods?

    Alistair - Reply

    FYI I had overtightened these bolts which caused my Left Z axis motor to have trouble turning and thus caused the calibration to fail. I loosened it a bit and it turned just fine.

    Andreas Sjolund - Reply

    Dear Prusa. Please stop using the description ‘trapezoidal’ nuts. You have supplied hexagon and square nuts. A trapezoid is a quadrilateral with only one pair of parallel sides. There is no nut like that.

    Tom Fountain - Reply

    Hi Tom,

    several other companies are using this term to describe the same shape (e.g. https://www.mooreinternational.co.uk/Pro...), how else would you call this one?

    Jakub Dolezal -

    I agree with Tom, just because other companies use a broad term doesn’t mean Prusa should . Take the feedback because its constructive rather than defending the reason. My challenge on this build ids is that I think you guys are rushing production because the resolution isn’t high enough for the square nuts to be properly located. the slots are either too narrow or the hole isn’t deep enough. I have been modeling for 45 years . If you want a yardstick for mold quality and precision fit buy any Tamiya model and spend a weekend assembling it and you will see that wherever there is a square nut located in a slot that part should be max resolution for precision, I was forced to dremel to locate the square nuts to allow the M3 18 mm bolt to meet the nut in alignment so that it could be tightened.

    PaulHarris - Reply

    Hi Paul,

    not defending, just explaining that I'm using description provided by the manufacturer, but I'm also opened to your suggestions and the manual was changed many times based on your feedback. That is why I asked Tom, how else would he call this part.

    Jakub Dolezal -

    None of the nuts included will allow for the inbedded area to be fastened. I can only secure the one side. The internal area does not allow enough space or the bolt to fit through.

    Bruce Wyman - Reply

    Well, contrary to many complaints here this stage was quite easy for me.

    I did make the mistake to put the “trapezoidal nuts” with the smaller diameter piece facing outside and had to unscrew, flip and screw back again. I suggest partly screwing to the nuts that go in the covered slots, and only then aligning the second screw and nut and finishing screwing both screws.

    perhaps modify the comment about the orientation of the “trapezoidal nuts”,

    e.g. “Make sure the narrower part of the “trapezoidal nuts” is inserted into the X ends.”

    or better yet have a wirefram drawing of the nut "outside” of the X-End and near it to emphesis the right orientation.

    Eyal Peleg - Reply

    I built mine as shown here, but before I ran the self test I watched the video https://www.youtube.com/watch?v=GE-lrRbU...

    titled on youtube “Original Prusa i3 MK3 guide for a new user” at time index 3:30 he says if they are not the other way around it will not work. What’s up?

    Les Kraut - Reply

    Having a terrible time getting the nuts into the slots. One goes in all the way with a little force. The other one does not. Any tricks for fixing this? After having waited forever for my kit, I really don’t want to wait for another motor holder.

    Brenda Bell - Reply

    If you are having trouble seating the M3n nuts, see the comments for the previous step 5.

    Andrew E. Mileski - Reply

    They’re called Trapezoidal nuts based on the trapezoidal thread form. (The screws you provide are not trapezoidal - not on the outside or in the thread form. The "Trapezoidal Nut" is the black plastic piece that is being fastened to the orange X-Axis part.) Please leave the correct term “Trapezoidal” in place. (Should I want to research, modify, etc, having the correct name would be beneficial - for example, should the desire strike me to make different trapezoidal nuts - I wouldn’t assume it’s different thread)

    (Maybe a label on the picture or in the description would make it clear)

    ref: https://en.wikipedia.org/wiki/Trapezoida...

    MattP - Reply

    They are called “lead screw nuts”.

    Timothy W. Skloss, Ph.D. - Reply

    As MattP mentioned above, “trapezoidal” nuts, as described by Moore Int’l. Ltd. in the link further above, could have just about any conceivable external shape. The cross-sectional form of the threads is their defining characteristic.

    Yet another example of a less than pellucidly-clear technical designation. “Lead-screw nut” might be a less confusing label, if not calculated to help Moore et al differentiate their product from lesser offerings.

    Meanwhile, getting the hex nuts into the innermost X-end traps without the aid of targeted invective turned out to be quite a trick. Good thing Wife was in the other room.

    steve hix - Reply

    I’m also have a lot of problems with the inside nuts. I can’t get either of them to fit into the slots enough to allow the screws to go in them. Trying to even use a small screwdriver to push them in, looking through the screw hole, the nut isn’t anywhere near being clear of the hole. I can only get 1 screw into each of the X-Axis Trapezoidal nuts. I’m hoping that is going to be strong enough to old them.

    John Haro - Reply

    I had the same problem. Try using the smallest Allen key going through the opening where you would put the screw so that you can also go through the hole of the nut. Then pull the nut into position.. That worked great for me.

    stephan -

    The slots for the square nuts are not deep enough. I had to grind the side of the nuts until they fit. I have had to clean material from every other hole to get hex nuts to go in. Print quality is not great. It took 6+ hours to get this far.

    William - Reply

    I had a problem with one of the trapezoidal screws, it cut off the head and I can't take it out, should I glue it and print another part?


    Esteban Camerlo - Reply

    The ONLY way I could get the two hex nuts closest to the bearings into a deep enough position to engage the screws was by using an awl with a modest taper, down the screw hole, with the awl’s point inside the nut, and then using a fair amount pressure against the side of the hole with the awl to lever the nut into place.

    If that had not worked, my next options were:

    - request new printed ends (UGH!)

    - dig out a small enough tip for my Dremel and a set of magnifying lenses, and hope I didn’t destroy the piece by gouging out too much plastic to still hold the nuts but enough to give the nuts room to seat.

    This REALLY needs some attention from Prusa. These holes are not controlled well enough for users to reasonably assemble.

    And having those 5 loose square nuts on the X-carriage from an earlier step was another headache! Those holes were plenty big enough… Just Don’t put them in so early!

    R.O. - Reply

    Wow, I started using my channel lock pliers to “press” these nuts (including all from step 2 and 3) into their proper position. Align the nut carefully and then just a gentle squeeze with the pliers pushes them right in. I don’t know how folks are doing this with just the tools provided.

    Rick - Reply

    • Aside from the X-axis, please prepare for the following step:

    • Smooth rod (2x)

    • Carefully slide the X-axis on the trapezoidal lead screws. By rotating both screws simultaneously let the X-axis slide until both trapezoidal lead screws are visible.

    • Make sure the top smooth rod of the X-axis and the lower edge of the frame are parallel.

    • NOW, PLEASE BE VERY CAREFUL! Gently insert the remaining smooth rods through the bearings on the X-axis all the way down into printed parts, do not apply too much force and do not tilt the rod!

    • In case you manage to push out balls from the bearings, please count them. One or two balls are ok, if there are more of them, please consider ordering new bearings.

    • Note: Design of your X-end printed parts might slightly differ, but the assembly process is the same.

    I missed the smooth rods part here…. …found out after calibrating part

    printminion - Reply

    Hi Printminion, was it unclear from the text or did you just follow the pictures?

    Jakub Dolezal -

    I’m having a problem where one the the trapezoid nuts is difficult to put on the threaded rod. Is this ok? I have to use a lot of force to slide the x axis down. I tried printing replacement nuts but those are hard to turn too.

    John Helgeson - Reply

    I found that sliding the nut up and down on the leadscrew a few times helped loosen up the fit a bit. The one of the left motor was far tighter than the right one in my kit.

    Robert Hunt -

    Hi John, the trapezoid nuts should be running smoothly and I haven’t encountered issues with them so far. Make sure your X-axis isn’t wider or inclined, this might cause increased friction.

    Jakub Dolezal -

    For the following step, please prepare:

    Smooth rod x2

    Robert heller - Reply

    Hi Robert, thanks for noticing. Since the rods are already on your working bench (table) and it is the last couple, I assumed to instruct you just to use them.

    Jakub Dolezal -

    Agree. I would have missed this step. I read it but confused because I didnt realize that the smooth rods were part of this step. Actually, I’m building this thing a few hours at a time here and there so it’s been awhile since I last saw or used smooth rods. So making this extra clear in the steps would be helpful.

    Andreas Sjolund -

    I agree, and Jakub’s reply makes little sense since all other steps specify exactly the parts needed to complete the step, regardless of whether they are “already on the workbench” or the “last couple” parts. If the instructions are to be clear and trustworthy, they need to be consistent.

    Guido Kimble -

    Hi Guido, you’re right step instructions will be updated ;)

    Jakub Dolezal -

    One thing I noticed is that the x axis bearings slid down the plastic holders when I put the rods in. I’m hoping this is ok since the x axis steps indicated that the bearings should be somewhat flush to the top and bottom of the plastic piece holding them (with a gap in between). I pushed the bearings back into place but not sure if they will just fall down again and if it will impact the printer in anyway.

    Daniel Lipsky - Reply

    Hi Daniel, it the best scenario the bearings should be aligned with both top and bottom edges of the X-ends (printed parts). However, slight movement in the printed part should be ok.

    Jakub Dolezal -

    You can use your flathead screw to push the bearing back up into place using the slot that exposes it.

    Todd Scott Anderson -

    We should put the trapezoidal by hand on the rods before screwing them at step 6. Its very easy to damage the trapezoidal nut because they are hard to put on

    there is no warning except ‘carefully screw the trapezoidal’.

    Is it a problem if the nut is hard to turn ?

    Jlevray - Reply

    Hi Jlevray, different approach during the assembly might brings issues. Putting on the trapezoidal nuts shouldn’t be hard, it should be smooth. If you have issues, please try to put on the nut without the X-axis. If everything works fine, then your X-axis is either too wide or assembled inclined, which is causing tilt between the nut and the trapezoid screws.

    Jakub Dolezal -

    I did damage both trapezoidal nuts using the standard instructions as the metal screws can easily cut into the starting thread while trying to find the right alignment. That led to endless debugging about why the Z-axis didn’t work correctly.

    I agree with Jlevray and strongly recommend carefully threading the nuts by hand first and screwing them to the X-axis second.

    LaurentR -

    Add one more to the agree with screwing on the nuts first. This was not an issue with the MK2, but seems harder with the MK3. Perhaps the spacing is slightly different. If you goof up the nut, you will either spend a ton of time trying to recut the threads with the leadscrew, or find an alternate solution such as printing temporary ones or stealing them from another printer as I did in the meantime. Mine was really tight right out of the box, so I am not sure whether it is the part or the process, however there is little left to guesswork if threaded on before being locked in.

    Douglas Shelfoon - Reply

    I’m also struggling with one of the trapezoidal nuts - it’s far too tight and I suspect it is causing the calibration failures that I’m now seeing. I’ve tried swapping the left nut with the right, and the same problem persists with just the one nut. I don’t recall putting it on awkwardly, but I might have damaged it. Although, it was also quite hard to remove from the screw shaft straight out of the box. It would be great if a spare was included with the kit!

    Sean - Reply

    I had the same problem. i just chatted with support and they are sending my a new nut.

    Joe -

    Hi Sean, the nuts are part of the Z-axis motors. In case yours are too tight, please contact our support.

    Jakub Dolezal -

    Similar problem :-(

    I may have damaged my trapezoidal nut.I was having a tough time with step “slide the X-axis on the trapezoid screws. By rotating both screws simultaneously let the X-axis slide until both trapezoid screws are visible. “

    After several times attempts i tryed running the nut backwards, and feeling the lip of the nut fall off the thread.

    One of them was impossible to start with out putting some torque on it.

    Now the left side X-access is very stiff.I removed the nuts from the x axis .

    1 nut is very tight fit to the lead screws.

    If i need to order new nuts please advise.

    Do you guys sell ball caps ?

    Joe - Reply

    Hi Joe, please discuss this issue with our support team (info@prusa3d.com). The nuts shouldn’t be preventing you from assembling the X-axis.

    Jakub Dolezal -

    Similar situation here. One of the trapezoidal nuts is way too tight.

    Sean - Reply

    Same here, one trapezoid nut is too tight, Z-axis motor with faulty trapezoid nut won’t move.

    Ivica Petrovic - Reply

    I initially had the same problem of getting the trapezoidal nuts started, and not wanting to cause damage as noted above, I stopped. I remembered that the nuts came off the rods back in Step 3 very easily, so I assumed there must be something else going on. What I did was as follows, and they both went on very easily: I sat the X axis on top of the rods (as everyone probably did). Then I rotated one of the rods backwards until I heard/felt a click as the nut dropped onto the thread. But that alone isn’t the trick. I then rocked the end containing the nut away and toward the frame while trying to rotate the rod into the nut - at some point it kind matches up and goes in very easily. I repeated the same thing on the other side with the same results. Seems like the nut needs to be on the exact axis of the screw rod to get it to start easily. NOTE: When I say “rod”, I’m talking about the threaded rod, not the one that the bearings run on. Sorry for the confusion.

    Ira Schonfeld - Reply

    I had the same experience as Ira. (Post above mine) I got lucky on one side and the nut threaded onto the rod easily. So she. The second side was difficult, I knew something was off. Simply rotating the threaded rod backwards a bit allowed the existing threads to drop into place, and then it was easy from there.

    Kalani - Reply

    Regarding the tight trapezoidal nut, what I see is the mass of the x motor is tipping the assembly off axis. I simply used one hand to straighten it and the other to start each side, once you get the thread started the assembly sits up straight.

    After setting the x axis assembly on top of the lead screws look at the printer from the side, and you will see what I’m talking about.

    Scott Carlson - Reply

    Do the leadscrews need any kind of lubrication? I’m asking here because I see no mention about the leadscrews in the maintenance guide.

    Manolis Agkopian - Reply

    Hi Manolis, to my knowledge there is no need. From time to time you can remove dust from the threads and before each maintenance have a look in the online 3D Printing Handbook to read the latest instructions.

    Jakub Dolezal -

    Same problem with trapezoid nut as reported by other folks here - one nut is *very* tight even when put on a screw rod alone. The other nut is fine - moves easily. There are no visible damage to the nut threads.

    Eugene Surovegin - Reply

    I’ve had no problem at all with this step . I’m wondering if the people having issues with a tight axis confirmed that the motor mounts were square to the frame . If not , the leadscrews could be leaning in or out and causing binding . Just a guess and another thing to try ….

    Marc Thomson - Reply

    I had the same problem with one of the trapezoidal nuts being very difficult to rotate. I’m going to try some of the suggestions here once I get back home. Plus, I sent a message to support asking to get a replacement nut.

    It seems like it’s VERY easy to cross-thread these [based on all the comments], so maybe a warning in the text to reinforce that the nuts should thread on easily and to check the threading if there’s resistance? I should’ve known better because I remembered the nuts un-threading from the rod nice and smooth in the earlier step. But, I got caught up in the excitement ;-)

    Tony Cacciarelli - Reply

    I also ran into one of the trapezoidal nuts being way too hard to turn. I put in a request via email to support for a replacement nut. Sigh.

    Christopher Dopp - Reply

    I know this is a bit extreme, but I too had a trapezoidal  nut that was either miss-threaded or just too tight. I took a blowtorch and lightly heated the end of the lead screw and the nut then screwed it on and off several times. It worked! It now glides as smooth as the other. Good luck!

    Lance Jensen - Reply

    If anyone makes it this far in the comments and still hasn’t figured out how to make the existing trapezoidal nut work, you might try printing a new one (for permanent replacement or as a temporary fix until a replacement gets shipped):


    This, of course, only works if you have another printer. Good luck.

    Darrel Raines - Reply

    So I bought the upgrade kit mk2s to mk3 and had to print all the parts, everything went ok however when assembling the z axis i noticed that my x-axis rods are not parallel to the frame, checked everything for many hours and turns out that the x-axis printed parts holes for rods are not 100% perpendicular to the side of the plastic part and I’m having the same issues as the one described on the next link (https://shop.prusa3d.com/forum/prusa-i3-...) however I dont know anyone that could help me by printing a spare part. I am hoping the self calibration process can fix the problem :s

    Juan López - Reply

    I’m having the same problem. Did you find a solution to this. Thanks.

    Erik Comtois -

    One of the nuts on mine was way too tight too compared with the other one. Caused calibration error right away, Z-axis wouldn’t even move by itself. The nut showed no sign of damage, but I found out where it was binding and used an Exacto knife to gently clean out some threads in that area. Took a little while but I was able to see significant improvement with very little material removed, enough to make it calibrate properly. They should include some spare nuts in the package.

    Scott Story - Reply

    When I got the parts, the “trapezoidal nuts” where already threaded on the threaded rods,

    So I knew that they should have no problem going back onto the rods.

    so when when I was going to start inserting the threaded rods into the rods and felt that they did not want to go in, i did not apply any force. Instead, I rotated the rods slowly in the opposite direction, until i head a “click” sound of the nut “falling” over the edge of the tread, then change rotating direction and it climbed on the threaded rod without any issues.

    In view of the many “I had the same problem” comments above I would suggest the “reverse-turn-until-click” method be added as a tip.

    Eyal Peleg - Reply

    This was a good reminder because I had already forgotten that the nuts were on the rods to begin with. Like you say, surely they should go on smoothly because of that reason. Therefore, any problems relate to the assembly and force should not be resorted to.

    Cliff Miller -

    After reading through all the comments, I too had tightness on the nut on the motor side. I tried the “reverse turn until click” approach but still met resistance. For me the problem lay not in one side being higher than the other, but the rotation of the X-axis assembly. Hard to explain clearly, but I rotated it ever so slightly in the Y-axis direction of travel and then the nut slipped right into the threads and spun with no resistance. So just another suggestion for anyone having troubles is to grab the X-axis motor/assembly by the side and rotate it like you’re turning a dial. That might do the trick for you. It really shouldn’t take any force at all.

    Cliff Miller - Reply

    I would suggest using two curved arrows rather than the two (blue) straight arrows as a better indicator for rotation (Step 7 first image). My first impression when those two arrows is “push-pull” not what I was expecting.

    Gene Dahilig - Reply

    Hi Gene, thanks for the suggestion. Unfortunately I don't have such option, but we are working on improvements ;)

    Jakub Dolezal -

    Not sure if it’s the kit I have now ( June 2018 - B6 ) but this section went really easy for me… only thing I did based on what was said in an earlier section was to reduce the length of the bolt on the right hand block on the x-axis, it was poking through the nut and didn’t want it to foul the vertical part of the frame at a latter stage when it would be really hard to fix it then…

    Martin Wright - Reply

    Instructions should mention that the top of the smooth rods and the top of the Z-axis lead screws should be level.

    This isn’t obvious until the next step.

    Though my smooth rods snapped into place, there was a good 3 mm more of travel required towards the faceplates of the Z-axis motors, which took a some effort, despite the holes being clean.

    Andrew E. Mileski - Reply

    After starting the right and left trapezoidal nuts on the trapezoidal Z-lead screws, turning the lead screws by hand was noticeable tighter than when I did my MK2S kit build.  However, the issue resolved itself after assembling the smooth rods.  Smooth rod ends apparently aligned the Z-lead screws to proper position.  Now I can turn the by hand the Z-lead screws easily.

    Ryan Fukuhara - Reply

    I had a problem with my left motor screw being too tight and not fitting (like so many other comments). I noticed my trapezoidal nut was being stripped by the process, too. The thought occurred to me that the weight of the motor might be causing the issue, so I held it while I turned the screw shaft and that worked perfectly. Hopefully my nut isn't stripped enough cause problems at this point, though.

    343 Guilty Spark - Reply

    Just adding my 2¢… the sluggish Trapezoidal Nut issue happened to me as well (weird how it seems to affect just 1 of them for almost everyone, eh?). Regardless if it’s an issue with parts/procedure/or person… I can share my fix, and it’s back to being perfect. 1: Try swapping left and right first just in case, you never know. 2: But what’s likely the issue as others have said; “a damaged trapezoidal nut” is causing it… so after looking closely, I noticed significant pieces of threading had gotten “shaved off” and lodged in the thread-spacing. 3: WITH EXTREME CAUTION, using a FRESH-BLADED Exact-o Knife more like a spoon [oriented 90° sideways], I just LIGHTLY scraped all of the debris clear… that solved 80% of the issue. 4: To get to 100% again? I can’t stress enough how CAREFUL and SLOW you need to be, but I set about reconstructing as SMOOTH & SHARP of a “thread-surface” possible while AVOIDING REMOVING material unless it couldn’t be avoided (a loose T-nut would be just as useless as a shattered one).

    David - Reply

    P.S. - DISCLAIMER: Only attempt my fix if you’re good with an Exact-o Knife, and think the “degraded”-threading situation applies to you. And if you get to 95% working-order; adding like a HALF-drop of high-viscosity, machine oil (the same type of stuff that leaves the oily-feeling residue on your hands after working with the LM8UU linear bearings) may also solve the rest of your case. It usually never hurts in situations of mechanical engineering to add a little “Friction Prescription”, outside of only a few certain special cases. And please make sure the oil you use is safe for all kinds of plastic, just to be safe.

    David -

    Terrible idea to have plastic part with thread installed on the metal one. I got the same trouble with tight nut, unfortunately this nut gets its thread damaged during installation when proper alignment of the axis is required. Instead of getting proper alignment of axis one nut’s thread is cut when trying to lower down the z axis.

    I hope that Prusa Research can provide with the spare “trapezoidal” nut.

    I tried to fix the problem on my own and I put the nut to the hot water, it got some elasticity and then I installed the nut again and it helped, now it is at least possible to move the nut, nevertheless the friction is much higher than on the other one.

    One nut I can rotate with two fingers without holding the threaded rod. Another I can rotate with two fingers while holding the threaded rod to prevent the rod from rotating. May I leave it as it is or will it cause some problems with calibration and printing later on?

    Marcin - Reply

    Hi Marcin, try to finish the build and see if the printer is able to move with the axis, if not, please contact our support at info@prusa3d.com to get a spare part.

    Jakub Dolezal -

    I too cannot install the trapezoidal nut. Way too tight.

    Jordan Damron - Reply

    I also had the left trapezoidal nut become tight (I swear, I will never do a step again without reading the comments first!!!!!!!). Fixed it by threading it down about a hands width then heating the threaded rod end with a heat gun for a full 60 seconds. Then threaded it back up over the hot end back and forth until it moved freely.

    Murphy Chesney - Reply

    Followup - This was the only mistake in an otherwise flawless construction - Calibration went well and many successful prints have been made. It is worth mentioning again: use a heat gun on the threaded rod to fix this!

    Murphy Chesney -

    Had the same problem, new ones are on their way after speaking few minutes to 24/7 support chat so 5 stars for ease of replacement so far :)

    I went through this step not thinking there might be a problem since the nuts went on seemingly fine - moving the screws by hand requires some force but I thought this was normal at that point.

    Maybe the manual should have something along the lines of “there should be no considerable resistance when rotating the screws” since I never suspected a problem until XYZ calibration when the Z-axis wouldn’t move at all. Not sure if that would actually save the situation though… I wonder why the nuts are initially (when taking them out of the packet) screwed in the other way around? They always went in easily this way, so maybe if they were the right way in from the factory it might be easier to do this step.

    John D - Reply

    Had the same problem with the tight nut on one side. The “good” side is super free when it moves. I can just flick it with my finger and it will spin a little bit. The “bad” side, I had to really twist to get to move at all. It’s an obvious difference if you have a good one vs the bad one.

    On the positive side, heating the rod and spinning the nut up and down it did help. It moves now, but not as free as the other side. After a quick chat with 24/7 tech support a new parts is being sent. It moves enough now that I feel I can go on with the build. I think this part should be easy to replace at anytime because it doesn’t appear to get covered by many other parts. Time will tell.

    IPT - Reply

    Surprisingly I had no trouble at all with the trapezoidal nuts. However, I was defeated by the next step of sliding the smooth rods down into the 3D printed motor mounts. While the right side worked perfectly, the hole on the left seems too small, and the rod simply will not go into it, even with quite significant force. I’ll try removing the motor and enlarging the hole, but that will have to wait until I can borrow the right drill bit.

    Arthur Tombs - Reply

    Hi there, sometimes it is hard to push it into that plastic part. Yet with a little bit of force you should be able to push it in without any problems :) (If you decide to drill the plastic part, be very careful not to damage it)

    Tomáš -

    Quick update: clearing the hole with a sharp 8mm drill bit solved the problem for me. I think there was a slight deformity in the plastic mount on the side closest to the motor shaft that caused the hole to be slightly out of round.

    Arthur Tombs -

    Glad to hear that you were able to solve the problem! :)

    Tomáš -

    It´s very easy to damage trapezoidal nut . had a problem with ma left one.

    Took ma an hour or more to get it done again.

    An lots of tools ;)

    Will request a spare nut fron support and change left nut afterwards.

    I suggest a different assembley procedure:

    Slide x-axis over screws from z-motor WITHOUT trapezoidal nuts.

    Then screw nuts all te way down to the x.axis.

    THEN screw M3 18mm screws in x-axis.

    Worked for me, avoids damaging trapezoidal nuts.

    nikolaus.brandtner@gmail.com - Reply

    When you drop the smooth rods through the bearings on the x-axis should they line up perfectly with the holes in the motor holder? I found that mine were off by 5 mm and needed to push them into place. Is this okay?

    pat - Reply

    Hi there Pat, are you sure that your X-axis rods were properly inserted into their plastic parts? This is the only thing which could possibly offset your Z-axis.

    Tomáš -

    I used small pieces of blue painter’s tape on the threaded rods as a rotation witness so they could be turned independently while one hand supported the X access while starting the threads. A small sharpie mark would work as well.

    dogma - Reply

    Although there are only two (2) bearing rods left at this point, please specify the overall length (not mentioned anywhere in the MK3 manual). Thanks :)

    Michele Palmieri - Reply

    • For the following steps, please prepare:

    • Z-axis-top-left (1x)

    • Z-axis-top-right (1x)

    • M3x10 screw (4x)

    I know the instructions are supposed to be serious, but I’d really add the following to them.

    Trivia: The hexagonal holes in these parts serve no purpose. They exist only to save some plastic (according to Vojtěch Soudný). The holes are commonly plugged by flags or figurines called “toppers”.

    Andrew E. Mileski - Reply

    Hi Andrew, I'm sure your comment will be sufficient for the other users passing this step ;)

    Jakub Dolezal -

    My part bag for this step contains 2 round black parts with holes in the middle. Parts are about dime size. No mention of them in manual. Looks like they fit nicely on top of the vertical rods?

    mjb - Reply

    Is it possible they might be the z screw covers from step 3?

    Grischa Grunau -


    those might be the Z-screw-covers, please check the step 3 again : 4. Z-axis assembly

    Jakub Dolezal -

    The smooth rod was not going all the way in for me. I had to lightly tap it with rubber mallet to level it with the lead screw.

    Jigar Patel - Reply

    • Place the Z-axis-top-left part on the rods and align it with the frame.

    • Ensure the holes in the printed part are fully aligned with the holes on the frame.

    • Use two M3x10 screws to tighten the Z-axis-top-left part.

    • Don't use excessive strength during tightening. In case of increased resistance, try to place the screws from the other side to "clean up" the hole. Then return to the front side.

    • Repeat this step on the other side of the frame with Z-axis-top-right printed part.

    • Note: Design of your X-end printed parts might slightly differ, but the assembly process is the same.

    refering to MK2 manual step 12:

    “Check both leadscrews in the upper part of printer, they shouldn't touch the edges of the printed part. If so, release the motor holder at the bottom and slightly move it. “

    You cannot see it from the top because the surface is full and solid. My leadscrew hits the edge what causes noise on fast movements of the x-axis.

    It is much easier to adjust the motor holder now instead after fully assembled and finished wire management.

    Heiko Schultz - Reply

    Hi Heiko, the Z-axis design was changed to prevent misalignment of the leadscrews. I will discuss this with devs, thank you for the feedback.

    Jakub Dolezal -

    it’s not an issue of the design, it’s just the assemble instruction that doesn’t highlight this. From below I can see if it is centered or not.

    Heiko Schultz -

    Hi Heiko (@predatorjr), the design was changed to align the rod correctly by itself and user shouldn't be checking the position, that is why it is not mentioned in the guide.

    Jakub Dolezal -

    I had an issue with the screw threads on the frame for the top right Z axis part.  I don’t think they were tapped properly because the screws were extremely tough to get in.  This was not an issue with the 3d printed part as I tried to work the screws in the holes without the 3d parts as well.  Ultimately, I had to carefully use my drill and was able to get the screws to go all the way in.  The top right 3d printed part does not sit tightly onto the smooth and threaded rod but there’s no play if I wiggle them with my hand.

    Shouldn’t be an issue but wanted to share my feedback.

    Corey Dryja - Reply

    The nyloc nut on the back of the x-axis sticks out, far enough that it holds the rods away from the frame, preventing me from attaching the right zxaxis holder to the frame.

    Not sure what to do other than use a regular nut instead.

    AMS - Reply

    not sure I needed to trim down the bolt sticking out of the x-axis carriage on the right hand side, now the brackets are fitted there seems to enough room for it to stick out as assembled in the text.

    Martin Wright - Reply

    Top left hole on the frame isn’t tapped right. Have tried multiple screws and a lot of force. The screw goes in about 1/16” and comes to a dead stop.

    Brenda Bell - Reply

    Well I just figured out what my problem was in this step (</sarcasm>)… I was going to post an image but right now the auto-spam filter thought I was trying to sell you guys something, etc. so I can’t. But yeah, Dear PRUSA… your instruction for “reaming-out” the hole from the other side I feel like is a bit of a method known as “jerry-rigging”… it may work in some cases but not mine. Not only was my M3x10 unable to even get started from the other side, but when tightening from the “normal side” once the screw was about 80-90% in, the head of the bolt snapped off. And it’s in such an awkward spot, it’s going to take methods normally reserved for medical surgery to devise a way to remove it when I inevitably modify/improve/upgrade/colorize my MK3. Of course there were all sorts of things I could’ve tried, I have a thread-reamer around here… but I don’t want to risk being at-fault for potentially making a situation worse and also for simplicity’s sake, devising a more “reliable” fix would be much appreciated.

    David - Reply

    Hi David, try removing the snapped screw using pliers, note the pliers must have tight jaws. If you are not able to do it, please contact our support at info@prusa3d.com.

    Jakub Dolezal -

    Finished this step last night. The top brackets do not hold the smooth rods very well. If I push down to get a click on the smooth rod , the bracket pulls away from the frame. Do I need to raise the motor bracket a bit? Or is this fine. or another solution. Thanks.

    Matthew Carrington - Reply

    Hi Matt! The bracket part may be badly printed, please send us photos of your parts and of your assembly to info@prusa3d.com, we will help you out and provide new parts if necessary.

    Martin Lexa -

    Had to retap the threads for these screws. Did it from the back. The threads were not even close! This is not acceptable.

    Jack - Reply

    • Starting mid of February 2018, the MK3 kit is shipped with improved X-carriage.

    • Compare yours against the picture and choose from following:

    • The old design is on the left side of the photo. Please proceed to Step 19

    • The new design is on the right side of the photo. Please proceed to Step 11

    my mid Feb kit showed up with the old design (in addition to the old version of the X end motor)

    Eric Harten - Reply

    Mine is old yet was shipped near the end of March :(

    Does it make much difference? Should I print a new one asap?

    Jeff Spencer - Reply

    I’d like to see this piece redesigned so the opening for how to slide the belt is on the other side with a small independent cap to cover it. Right now the only way to “adjust the belt” or replace the belt require a complete removal of a rather complex set of wires as shown in another section.

    Ed Burgueno - Reply

    • Insert the flat part of the X-GT2 belt (850 mm) into the X-carriage as in the picture.

    • Use a screwdriver or the smallest Allen key to push the belt in.

    I can´t manage to insert the belt! Its stuck halfway in, how should I do it?

    William@stadheim.com - Reply

    Hi William, check the slot for any obstacles first. If it doesn't help please contact our support according to the options in the first chapter of this manual: 1. Introduction

    Jakub Dolezal -

    My X-axis belt is only 740 mm in length. The Y-axis belt is already installed and was the correct length, so I don’t think I’ve switched them. I’ll probably source a replacement locally but wanted to point out that this happened.

    Eric Lee - Reply

    Be reminded not to push the belt to the full depth of the slot or your cannot achieve the alignment in step 15. A depth similar to that in the photo works well.

    Siu Chuen Chan - Reply

    • Guide the X-axis belt through the X-end-idler, around the 623h bearing with the housing and back.

    • Continue with the belt through the X-carriage. Note there are slots below the belt, those will be used for cables.

    • Guide the X-axis belt through the X-end-motor, around the GT2-16 pulley and back.

    I would recommend using a single curved arrow rather than several straight arrows to show that the belt goes around the 623h bearing.

    Gene Dahilig - Reply

    Hi Gene, unfortunately this is current limitation of the system, but we are working on improvements ;)

    Jakub Dolezal -

    I had to adjust this part to push it closer to the motor

    Craig Bennett - Reply

    • Before you continue to guide the belt through the X-axis, please release two M3 screws on the X-end.

    • Rotate the X-axis motor as indicated towards the frame.

    • Insert the flat part of the X-GT2 belt into the X-carriage as in the second picture.

    • Use a screwdriver or the smallest Allen key to push the belt in.

    • There will be belt overhang on this side, DON'T TRIM IT yet.

    Is the motor supposed to pivot on the bottom screw? By “release,” do you mean a half turn looser or fully retracted from the motor housing?

    It looks like the screws should be able to move slightly side-to-side on the top two, but the openings are too small to allow that kind of movement.

    Evan - Reply

    Hi Evan, leave the motor connected just on the bottom screw, the upper two screws can be almost “removed”. Your aim is to rotate the motor as close to the frame as possible.

    Jakub Dolezal -

    While the motor does not move very much at least I can see that there is allowance for movement by the use of oval’s cut out where the two pivot screws are. I wish they had did the same thing for the Y belt, it wants to run right against the pulley and I think that I have the belt placed just right elsewhere. Would be good to use an oval opening for the motor to frame and then use a screw with washer so can position left to right.

    mjb - Reply

    I don’t seem to have very much rotational freedom in the motor; it won’t rotate as far from vertical as in the picture.

    Arthur Tombs - Reply

    Hopefully the mk4 will have a real belt tension system…

    dogma - Reply

    • Using right hand rotate the motor to its original position and hold it (tension is applied to the belt).

    • Using two fingers on your left hand push the belt together. Very small force should be needed for bending the belt, BUT the belt shouldn't be bent by its own weight before being pressed with your fingers, it must be straight.

    • If you are struggling to rotate the motor back into position the belt tension is too high.

    • Depending on the belt being under or overstretched, adjust the amount of the belt in the X-carriage.

    • When done, rotate the motor to its original position and tighten the M3 screws again.

    I would clarify the “original”position is the one where tension is applied to the belt.

    Rich - Reply

    Good point Rich, description added. Thanks

    Jakub Dolezal -

    I’m not sure if I should have cleaned out the screw areas first, but my motor wouldn’t rotate to the left, even with some force applied. I wonder if the channel for the shaft is too tight (I had to “screw” them into the plastic to get them to seat on the motor. So there is very little (1-2mm) play is all between “rotated” and not. While I was able to get the belt seated securely, is this going to be a problem long term?

    Ben V - Reply

    There is no need to worry about it, if you were able to properly tighten your X-axis belt.

    Tomáš -

    I also think this description is a bit strange. I just tighten it and went for it.

    Marijn - Reply

    I totally misread “original position” as “the most slack position”. Thank you, Rich, for your clarification.

    Brad Needham - Reply

    • Both top and bottom part of the belt should be parallel (above each other).

    • To adjust the belt position, release the screws on the pulley and move it slightly until you reach the best position.

    • Tighten both screws on the pulley.

    I don’t know what it is, but the belt rubs against the X-axis where the motor is. It rubs on the outside edge, and looks like the X-axis part is not wide enough for the motor. In other words, I cannot push the pulley any closer to the motor without it rubbing, and the belt is against the far side of the X-axis part. Any ideas?

    Jason Conaway - Reply

    Please disregard my question. I had a moment of poor judgement and put the pulley gear on backwards.

    Jason Conaway - Reply

    Ditto. I’m an idiot.

    Jeremy Mayes -

    Same here :(

    Jeff Kerwin -

    Easy to do! Maybe back in the step where the pulley is put on the motor there should be more than just a picture. I lucked out and caught myself after placing the pulley on backwards.

    Gary Shumway -

    I did that too, but I noticed it during the next few steps and fixed it.

    David Thompson - Reply

    Does the belt always ride to the left or right? I can’t seem to get my belt to stay precisely in the center. This is true for the idler and motor side of my Prusa mk3 and mk2.

    Ludvik Jersbek - Reply

    i did the same mistake…..i put the pulley wrong…

    Christos Goulas - Reply

    I repeated the process from the Y Axis: I loosened the pulley, pushed the extruder mount all the way left and right while looking at the belt position on the pulley - the belt should have roughly the same in-out clearance on the two sides of the pulley. I then moved the pulley in or out a little and pushed the extruder mount again, repeating the process until the belt rides right in the middle of the pulley. I then tightened the pulley screws.

    Brad Needham - Reply

    Same here - installed it in a wrong way

    kchilingarashvili - Reply

    Wow yeah I’d skip this test I thought I’ll go no and easy could not feel any tension and then snap plastic separated :( I don’t think I ever noticed any increase in tension.

    Ben - Reply

    I found it helpful to center the belt in the pulley. Then I moved the x-carriage back and forth. The belt would always un-center itself and rub against one side. So I moved the pulley on the shaft until the belt stayed centered.

    Graham Entwistle - Reply

    Ugh. Same thing.


    joining the party on the wrong orientation of the pulley!

    patjmulligan@gmail.com - Reply

    • Use the technique described below to test if the belt is properly stretched.

    • Use pliers to hold the X-axis motor shaft.

    • Move the X-carriage towards the X-axis motor. Don't use excessive force.

    • If the belt is stretched properly, you should feel a resistance and the X-carriage won't move at all. If the belt is too loose, it will deform (create a "wave") and jump over the teeth on the pulley.

    • Belt too loose? Return to step 13 and repeat all steps until now. You have to rotate the motor and retighten the belt in the X-carriage. Shortening the belt length by moving one or two teeth outside X-carriage should be enough.

    Add Comment

    • For the following step we recommend getting a white marker, but you can also trim the belt without it.

    • Measure the part, which must be trimmed and gently take the end of the belt away, from the X-carriage, but make sure at least 3-4 teeth are still in the X-carriage, as you don't want to lose the tension. If possible make a mark, where to cut the belt.

    • Ensure again your mark is in the correct position and the belt is still stretched.

    • Using pliers cut the belt and push it inside X-carriage. Use screwdriver or Allen key, if needed.

    Finding a “proper” belt tension has always been an issue, so if the frame measures are well known (as they are), shouldn’t the belt length be known as well? Why don’t you just say “cut the belt down to X cm and mount it as shown”?

    Arsen Torbarina - Reply

    Hi Arsen, it is not that easy. All products have a certain tolerance, so you can't give one number of length without testing it for a while. Because for some it might be a bit too long, for some a bit too short. As soon as we have enough data I'm sure we will cut the belt for you.

    Jakub Dolezal -

    After cutting and pressing in the end of the belt, you may want to check the belt alignment again, in case it was pressed in further than before.

    Etienne van Ballegooijen - Reply

    I would recommend not attempting to trim the belt with pliers as suggested, I used a hobby-style exacto knife instead and it was super easy and clean.

    blueyes13@gmail.com - Reply

    Hi, it is possible to trim the belt with the bundled pliers, but you can use your own tools :)

    Jakub Dolezal -

    For the belt length I have to agree, allowing for tolerances it would be easier to have the belt slot to be longer at the “overlength” end , any extra could just be lost in that slot and there would be no need to trim the belt..

    Martin Wright - Reply

    Hi Martin, we are working on it, the plan is to have the belt trimmed directly in the factory .

    Jakub Dolezal -

    I didn’t know white markers existed. I’ve never seen one before, and I’m over the half-century mark.

    I used a bright orange grease pencil (a.k.a. china marker, wax pencil, chinagraph pencil, butcher’s pencil) that I had purchased at a big-box hardware store (ask a store associate to help you find it - I think it was in a tools section with carpenters pencils).

    Might wan’t to add that to the instructions.

    Andrew E. Mileski - Reply

    I used a toe nail clipper. Worked great.

    Ed Roberts - Reply

    • In this step, we will finish tensioning the belt. Please read the instructions first, your belt might have proper tension already.

    • First, slightly release all the screws holding the motor, otherwise, the upper "tensioner" won't work (the motor must be able to move).


    • Using Allen key start tightening the M3x18 screw inside the X-end-motor, but after each turn or two check the tension in the belt.

    • In Step 14, you were asked to have the belt a bit less stretched, however, for the optimal performance, the belt must be a bit harder to press with your fingers. Move the X-carriage all the way to the X-end-idler and try the belt tension in the middle of the X-axis.

    • When you achieve optimal tension, please tighten the screws again.

    • In case you experience X-axis failure during calibration or skipped layers in the X direction, you can adjust this screw accordingly. Tightening the screw stretches the belt. Releasing the screw has opposite effect. Each time don't forget to release the screws on the motor first.

    • Ready? Please jump to step Step 25

    With regards to the correct tension, won’t it be possible to design a weighted scale, one that hangs on the belt, this might insure that the correct tension is achieved during construction and when doing maintenance further down the line.

    Regardt Jordaan - Reply

    This step needs MUCH better instructions. “a bit harder” is not a real specific term. Also with the new pieces printed in PET they won’t take as much stress as the ABS parts. At least give a reference to how much deflection the belt should have or some kind of scale as quoted above.

    Greg Sargent - Reply

    Not understanding the purpose of the X-end-Motor Tensioner Assembly M3x18 screw I over tightened it and broke the assembly. This may cause multiple issues with the X-axis assembly because I don’t know how hard it will be to remove the damaged part from the smooth rods.

    I may have to break of the plastic part to get them loose from the rods because that’s a tight fit.

    David Thompson - Reply

    broke mine :-(

    process was definitely improving tension on the belt - but not clear how many turns, or how much slack was acceptable. I was still able to comfortably touch upper and lower belts

    scott hansen - Reply

    I just broke my X-end-motor bracket. :( Was following printed manual (with errata insert for this step), but this looks to be the same. I have B6 version. I tightened the M3x18 screw and eventually plastic bracket de-laminated close to the nut hole. The belt was nicely tensioned, but it was not tensioning any more, but I kept turning the screw, it probably touched the other screw and just put more stress on the bracket which eventually failed. It would be nice to have: a) more material in the left-top corner, c) much bigger washer, d) some window to see the position of the screw inside, e) a way to measure the tension of the bracket and belt in objective way.

    I managed to finish the build anyway, with broken bracket. It works flawlessly actually with perfect print results. I will glue the X-end-motor bracked later back to good shape, and print replacement (possibly with strength improvement modifications), or order new one. :/

    Witold Baryluk - Reply

    Exactly what I did

    Jason Cumiskey -

    Same situation… at the very least should have a warning that this will happen, I didn’t even twist with that much pressure.

    Kent Ogden -

    same here, just snapped mine while tightening it. seems like the belt is holding tension so i should be able to print a replacement after my build is finished.

    Mike Walker -

    I am really sorry to hear that. Will make some adjustments to this part of the manual.


    Tomáš -

    Totally agree with the above. I don’t have a lot of experience with belt tension, so “a bit harder” is a bit of a struggle.

    Zachary Loafman - Reply

    Ditto. Mine’s broken too. Now what?

    James Smith - Reply

    Hi James, please contact our support using a live chat, visit shop.prusa3d.com and look for the chat window.

    Jakub Dolezal -

    Mine broke as well. It didn’t break off completely, but there’s a big crack to the right of the top left screw from top to bottom. Seems to be holding itself together alright, just going to continue and hope it works out. I agree it’s unclear how tight the belt should be.

    Clay Smith - Reply

    At some point, the square nut trapped in my motor mount got misaligned, so I was never able to use the tensioning screw. But based on seeing how many people had their mount break, I think that the tensioning screw may be a bad idea. I tensioned my belt very easily by hand. Just loosen the three motor-mounting nuts and rotate the motor frame by hand to achieve the desired belt tension, then tighten the bolts. By the way, during Calibration (which comes much later) the electronics will measure the effort required to move the belt and will give you a numerical gauge telling you if you have done it right. So don’t obsess about getting the belt tension “just right” at this step.

    Jay Sinnett - Reply

    And to add to the list of issues, my x axis motor snapped when tightening the tensioner screw.

    I would definitely add a warning in the text of this step as it seems to be a common problem.

    Going to continue with the build as things are holding together OK still, but going to print a replacement part (to go with the pair I ordered today) as soon as its all up and running well.

    If nothing else, I've learned to read these comments before starting a new step :p

    Rob Ryan - Reply

    Mine broke, too. It didn’t seem to tighten the tension either.

    Bruce Wyman - Reply

    In no way am I recommending a particular strategy either way regarding this step…. but I paid about 0% attention to it. My belt was perfect from the previous steps already. The only thing I did do was screw the M3x18 bolt in far enough to keep the M3nS nut secure in it’s slot. IMHO, I think it’s best to just move on with the build and if you’re THAT concerned… just watch for any weird behavior while printing and revisit this.

    David - Reply

    Will the tensioning screw also not damage the screw into the motor?

    While a significant redesign would be required, is it not possible to have carriage have a device to tension more, IE a toothed gear (like on the motor) that could be tightened and then locked into position, allowing all tension to be created at the carriage instead of via a motor mount? It would allow for much greater range of motion, as well, as the belt ages.

    Ben V - Reply

    Broke my part using the end screw to tension the X-end-motor bracket. I’ve used liquid cement to create a plastic weld and I’ll see if it holds. Will have to order a new part for the long term.

    Jason - Reply

    Aaaand it broke for me too… -.-

    Daniel Aas - Reply

    Yeah, broke min as well. (After completing the build…) This step definitely needs a big red warning!

    Quick fix at the moment: released some stress and apply super-glue to the starting delamination. Now considering if I should calibrate the printer and start printing a replacement or directly order a new one from prusa.

    I am not looking forward to the re-assemble…

    Andreas Schmidt - Reply

    I (luckily) didn’t break the part. I tensioned the belt first, then just turned the 18mm screw until I felt some resistance. It seems like a bad idea to use the 18mm screw to adjust the belt tension - it seems better to use it to hold the previously-set tension in place.

    Brad Needham - Reply

    I agree. This step is a bit confusing. Maybe a picture showing what “taught” looks like or some kind of aide. Glad I read comments about warnings of breaking.

    Joshua Reed - Reply

    Hi there Joshua, will think about something.


    Tomáš -

    Super odd that the belt slides in from this side. If the piece was redesigned so the belt with small cover was on the other side of this piece we could easily replace the belt if we break it or the belt becomes to stretch and needs to get taken off and put back on a few teeth down. Everything that goes on top of this piece shouldn’t have to come off to replace a broken belt.

    Ed Burgueno - Reply

    Thank you for your feedback Ed :)

    Tomáš -

    I adjusted the tension in the belts to give the note A2 or 101 hertz checked with the free smartphone app n-Track Tuner this might not be the right note but I sing the Base line so it is what my voice tunes when I ask for a note from the accompanist ;-) and it is at least consistent. I would suggest that back when mounting the X axis motor, you ask folks to be sure those oblong slots in the mount are clear and that when they mount the motor that it will pivot its full swing when only the bottom screw is slightly snug. I had to remove it and lightly with a swiss needle file clean out the slots to provide said free movement.

    Mustrum Ridcully - Reply

    Broke mine too… still holding tension.. I think the tension was ok before this step had me mess with it! We’ll see what happens later!

    Robert Eden - Reply

    Hi Robert, glue it and reprint is as soon as possible or contact our support to get a replacement ;)

    Jakub Dolezal -

    • DON'T TRIM THE BELT unless you are asked in the instructions!!!

    • Insert the flat part of the X-GT2 belt (850 mm) into the X-carriage as in the picture.

    • Press the belt all the way in, use a screwdriver or an Allen key.

    • It's very IMPORTANT that the short end of the belt isn't sticking out of the X-carriage.

    “Insert the flat part of the X-GT2 belt (longer one) into the X-carriage as in the picture.”

    What you mean by “longer one”?

    Austin Hampton - Reply

    It seems to me the X belt is longer than the Y belt.. so if you unpacked everything all at once and not step by step “longer one” would tell you which is which.. but how you would get to this step with more than one belt from one kit is a mystery =)

    Thomas Kasner -

    Step description updated with exact length of the belt. It should be a check for those, who switch the belts by accident.

    Jakub Dolezal -

    I think it’s a mistake to “press the belt all the way in”. I think this is the reason that many people are experiencing belt rubbing on the front shoulder of the pulley and resultant belt twisting. Instead the belt should sit flush with the outer edge of the round mount.

    Ken Hackbarth - Reply

    Hi Ken, no it is OK as described in the manual. The belt should be completely pressed in. I need to see your printer, to examine the possible cause of the rubbing.

    Jakub Dolezal -

    • Guide the X-axis belt through the X-end-idler, around the 623h bearing with the housing and back.

    • Continue with the belt through the X-carriage. Note there are slots below the belt, those will be used for cables.

    • Guide the X-axis belt through the X-end-motor, around the GT2-16 pulley and back.

    Add Comment

    • Before you continue to guide the belt through the X-axis, please release two M3 screws on the X-end.

    • Rotate the X-axis motor down.

    • Insert the flat part of the X-GT2 belt into the X-carriage as in the second picture.

    • Press the belt all the way in, use a screwdriver or an Allen key.

    • There can be a slight belt overhang on this side, no need to trim it.

    When I was doing this step, the belt teeth were slipping over each other, even without significant tension. I concluded that the “pinch points” in the printed part (the X-carriage) were not tight enough. I cut 2 small squares of thin (0.25mm), hard plastic (from the plastic wrapper from the packaging of a 9v battery), and slid them in above the overlapping belt The location is pointed to by the upper green arrow in the second picture. It stopped the slipping and it worked perfectly after that.

    Kevin Gallagher - Reply

    Same problem, as soon as i try to tight with the motor, it slips…:-(. I agree with Gerhard, even if after trained myself on MK2, it seems easier to use this fixing belt today, when it holds something !

    Jeremy -

    A sugestion for a Version MK3S or MK4: another fixing for the belt.

    It was a pain to get this in in the right position.

    Gerhard Kunz - Reply

    mk3.jpeg No problem here

    Valentin Bulbuc - Reply

    • Using right hand rotate the motor to its original position and hold it.

    • Using a finger on your left hand push the belt down. Some force should be needed for bending the belt, BUT don't try to overstretch the belt as you might damage the printer.

    • If you are struggling to rotate the motor back into position the belt tension is too high.

    • Depending on the belt being under or overstretched, adjust the amount of the belt in the X-carriage.

    • When done, rotate the motor to its original position and tighten the M3 screws again.

    Add Comment

    • Both top and bottom part of the belt should be parallel (above each other).

    • To adjust the belt position, release the screws on the pulley and move it slightly until you reach the best position.

    • In case you can't make the belt parallel, check if the belt is properly inserted in the X-carriage.

    • Tighten both screws on the pulley.

    If the pulley screws are not tightened really properly, it may cause a random x-axis layer shifting later, if they become loose!

    Miroslav Piencak - Reply

    I am having an issue with the belt touching the printed pat that holds the motor. It catches the side of the printed part away from the motor toward the rod and screw. I have tries pushing the the pulley all the way against the motor but it still will not clear the opening in the printed part as it passes through to the x-carriage. This causes the belt to tilt in toward the front side and away on the back side so it looks like a long V that does not quite connect. I was thinking I might cure this by placing washers between the printed part and the motor to give me additional shaft so I can push the pulley back far enough to clear the opening in the printed part. However, this seems likely to create additional problems later. I suppose a stiff gasket material that covers the top of the motor might be less risky, would need to search for something like that. Is there another adjustment I missed here that might cure this problem? It seems to me this may cause the belt to be unstable and wear badly if not fixed.

    Harry Townsend - Reply

    Solved my problem, I put the pulley on backwards…

    Harry Townsend - Reply

    Does the belt always seem to pull to the left or right? I have a Prusa i3 mk2 and mk3 and this happens on both the motor and idler side. I’ve tried to get it to ride in the center but it always drifts to one side or the other. Any help would be appreciated.

    Ludvik Jersbek - Reply

    IS there a way to accurately check if its parrallel? Is there a tool we can use?

    or is it all eyeball?

    Brian - Reply

    Hi Brian, check the belt with your eyes, it should be enough. You can move the extruder back and forth to see, whether the belt stays parallel.

    Jakub Dolezal -

    • Use the technique described below to test if the belt is properly stretched.

    • Use pliers to hold the X-axis motor shaft.

    • Move the X-carriage towards the X-axis motor. Don't use excessive force.

    • If the belt is stretched properly, you should feel a resistance and the X-carriage won't move at all. If the belt is too loose, it will deform (create a "wave") and jump over the teeth on the pulley.

    • Belt too loose? Return to step 12 and repeat all steps until now. You have to rotate the motor and retighten the belt in the X-carriage. Shortening the belt length by moving one or two teeth outside X-carriage should be enough.

    Small gripe: It should say to return to step 20. Step 12 is for the new design X-carriage.

    Torsten Lif - Reply

    • Z-axis is done! Time for another gummy bear. You still have some right? :)

    • Check the final look, compare it to the picture.

    I ran out of gummy bears, why aren’t there any in the spares kit ;).

    Mitch SPacone - Reply

    Good point Mitch! I will suggest this to Josef :D

    Jakub Dolezal -

    I ate all of the gummy bears immediately after opening the box, was that wrong?

    Suzan Kowalski - Reply

    • Open the paper tube and look for the spiral wraps or textile sleeves inside. There are two possibilities:

    • There are only textile sleeves present in the kit, then proceed according to the: 5. E-axis assembly (textile sleeve)

    • There is a combination of spiral wraps and textile sleeve in the kit, then proceed according to the: 5. E-axis assembly (spiral wrap)

    Add Comment

Finish Line

766 other people completed this guide.

Jakub Dolezal

Member since: 02/20/2017

107,410 Reputation

163 Guides authored


One hour, tensioning was a bit time consuming.

Scott - Reply

35 minutes. :D

Zaz - Reply

Difficult to insert the beginning of the belt into the carriage but not the end. Some slight production variation?. Managed anyway. Looking good at this point.

Henry Casson - Reply

Up until this part, I used the printed assembly instruction - because it is easier to have a book on the work table than a computer. But the printed pictures of the black X-carriage and the black belt were impossible to see in any detail, so I had to come here. I think some sketches of the belt path would be a huge improvement.

Torsten Lif - Reply

Step 21 can be a little difficult when trying to place the loop. what i found that helped was to use one of the tie wraps, place the thin end under the top belt to help keep it up and off the bottom. this made the process go a lot quicker with less frustration. once the lower part is engaged sufficiently just remove the tie wrap and press the belt to the bottom.

Philippe Desjardins - Reply

to add to what was said before .. I think some of the black printed parts need to be either printed in a gray or painted gray so they show up better

Edward Traxler - Reply

Hi Edward, thanks for the suggestion, I appreciate it. Using different color leads often to confusion, whether the part is different or new. I will think of a way to adjust the current step, maybe reshoot the pictures.

Jakub Dolezal -

After Z-Axis finished there is material leftoverr:

4 x M3 x 10

1 x ‘M3 x 18 (missing at X-Axis)

1M3nS (missing at X-Axis)


Werner Zoechling - Reply

I had the M3 x 18 & 1M3nS show up here as well (needed back one section), no extra M3x10’s

Lee Clark -

The right trapezoidal nut went in after a little finagling, but I’ve spent 20 minutes trying to get the left one to fall into the nut trap(step 5). Anyone have any advice?

Albert Yu - Reply

Hi Albert, always check whether there is some obstacle in the slot preventing you from inserting the nut. You can use sharp tool to get those obstacles away, but be careful ;)

Jakub Dolezal -

use one of the smaller allan keys to go in the screw hole and push it in the hole in the nut (should manage to do that even if the nut is not in all the way). Then you can use the allan key as a lever to slide it fully in.

David Kaufmann -

Step 5 was very difficult.  Inserting the inner M3n in both X ends was problematic.  After getting the nut in I managed to cross thread the screw which allowed the nut to rotate during tightening on both X ends.  I think more detail in needed on inserting these nuts.  I have decided to continue the assembly.  Is this a good idea or should I buy a completed X Assembly?  I don’t think I could get the x rods out of the X ends.

Karl Dickens - Reply

Hi Karl, no need to buy the axis preassembled. Finish the assembly and see how the printer performs. I think rotating M3n won't be an issue. You can print new X-ends yourself, if needed. Removing the rod is possible, but it takes certain force.

Jakub Dolezal -

1.5 hours just on step 5. The design is flawed.

Oh another 20 minutes trying to get my Trapezoidal but to wind back down the lead screw. Gave up and having a replacement sent out. I was ready to bin the kit

Stephen York - Reply

I have 2 printed conical washers left after assembly. These were in bag 4. Didn't see anything in the process to use these. Did I miss something?

Adam - Reply

It’s easy to miss, they are used in step 3. You remove the trapezoidal nuts and then immediately spin the cones down the lead screws until they are next to the motors. They really should make those orange instead of black to make it easier to tell what’s going on in those pictures. In the second picture they aren’t showing the trapezoidal nuts next to the motor, those are the cones.

Dave S -

I made the same mistake. Fortunately it only takes a few minutes to drop the motor and shaft and fit to them on.

DavidNutton -

Both of my Motors have the same length cables where the guide says one is longer than the other [Step 3]. Both about 560mm. Hope not a problem so I have fitted them an finished this axis.

DavidNutton - Reply

45 minutes to assemble, needed to use a thread chaser on two of the threaded holes in the frame, no problem though from experience I know that aluminum threaded holes are easy to muck up if you start the screw a little off. Once again thanks for spare kit.

Ricky Burnett - Reply

I’d never heard of a thread chaser before. Thanks for teaching this old-dog a new trick!

[For others: Dies & taps cut new threads, where a thread chasers clean-out / restore existing threads. If you used a tap on an existing threaded hole, you’d risk damaging or removing the thread! A thread chaser is used instead.]

Andrew E. Mileski -

You didn’t say to save the gummybears! My gummybears where all consumed by the end of unboxing and inventory of parts! Please warn users to ration the gummy bears…Note this is just a joke, great job so far!

Luke Davis - Reply

Hi Luke, seems to me somebody wasn't following the instructions … :D Enjoy the assembly and let me know if you find any difficulties along the way ;)

Jakub Dolezal -

@jakoob - it would be great if you could add a “thumb” or something to these comments so that we could indicate which challenges we shared or which answers helped us. I know sometimes when I am looking for something, having a numerical indicator helps me find the most frequent/common issues instead of searching through the entire thread for every step.

Ben V - Reply

I did not encounter any issues at this section despite the multiple steps with greater than 50 comments. I attribute that to the great and numerous comments on the tricky parts which allowed me to focus and proceed with caution. I greatly appreciate the assistance fellow builders have provided. Also, it seems maybe the parts were revised to adjust for fitment issues. B6 is my version and that seemed to have a lot of issues earlier in the year So if you are getting the kits in Aug or later you should be good but still check on the steps with multiple comments!

JBFLA - Reply

only issue for me on this set was the textile sleeve. Patience persevered.

Doug Kline - Reply

Tensioning the belt was pretty easy. It helps to keep the relevant screws a little loose everywhere, and then tighten up as you get to the last step of tensioning. It’s easier to get the belt in place that way. A bit tricky getting the belt pushed all the way into the carriage at first, but since I took it on and off a few times to get the tension right, it got easier each time (experience!).

Matt Laudato - Reply

Add Comment

View Statistics:

Past 24 Hours: 125

Past 7 Days: 875

Past 30 Days: 3,865

All Time: 51,301