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  1. Needle-nose pliers for zip tie trimming.
    • Needle-nose pliers for zip tie trimming.

    • 2.5mm Allen key for M3 screws

    • 1.5mm Allen key for nut alignment

    • Philips screwdriver to tighten PSU and HB cables

    • WARNING: Make sure to protect the electronics against electrostatic discharge (ESD). Keep the Einsy board in the antistatic bag until it is needed for the assembly.

  2. For the following steps, please prepare:
    • For the following steps, please prepare:

    • Einsy-door (1x)

    • Einsy-hinge-top (1x)

    • Einsy-hinge-bottom (1x)

    • M3nS nut (1x)

    • M3x10 screw (2x)

  3. Insert M3nS nut all the way in. You can use the small screw driver to push it down if needed. Check the proper alignment with the Allen key.
    • Insert M3nS nut all the way in. You can use the small screw driver to push it down if needed.

    • Check the proper alignment with the Allen key.

    • If this nut is loose in the slot then it can easily fall out and then possibly short some electrical contacts on the Einsy board whenever you open your Einsy case.

  4. Turn the rear side of the printer towards you.
    • Turn the rear side of the printer towards you.

    • Holes with blue arrows will be used to mount the hinges for the Einsy-door.

  5. Take the Einsy-hinge-bottom and push M3x10 screw through. Note there is a cutout for the screw's head in the printed part. Locate the hole for the lower hinge.
    • Take the Einsy-hinge-bottom and push M3x10 screw through.

    • Note there is a cutout for the screw's head in the printed part.

    • Locate the hole for the lower hinge.

    • Place the hinge on the frame and tighten the screw. The hinge must be facing upwards.

  6. Place the Einsy-door on the lower hinge. Take the Einsy-hinge-top and push M3x10 screw through. Assemble the Einsy-hinge-top in the door and mount it to the frame.
    • Place the Einsy-door on the lower hinge.

    • Take the Einsy-hinge-top and push M3x10 screw through.

    • Assemble the Einsy-hinge-top in the door and mount it to the frame.

  7. For the following step, please prepare: Textile sleeve 5 x 300 mm (1x) Zip tie (1x)
    • For the following step, please prepare:

    • Textile sleeve 5 x 300 mm (1x)

    • Zip tie (1x)

    • Wrap the sleeve around the X-axis motor cable. The sleeve is shorter, than the motor cable.

    • Secure the sleeve using a zip tie, you have to tighten the zip tie firmly and it is only a temporary fix until the Einsy case is assembled, but you can leave the zip tie in place afterwards.

  8. For the following steps, please prepare: Einsy-base (1x) M3x10 screw (6x)
    • For the following steps, please prepare:

    • Einsy-base (1x)

    • M3x10 screw (6x)

    • M3nS nut (4x)

    • M3n nut (4x)

    • EINSY RAMBo motherboard (1x)

    • Einsy-base has a maintenance opening for the RPi Zero W. If you intend to use this mini computer, you can carefully cut the piece of the plastic now. More details here: Octoprint for the MK3 (manual.prusa3d.com)

    • Note that the anti-static bag will be opened upon arrival. Each board is taken out and tested before shipping.

  9. Take the four M3nS nuts you've prepared earlier and insert them in the Einsy case the following way: Two nuts inside the heatbed holder (note one slot is from the inside of the cover) Two nuts inside the extruder cable holder.
    • Take the four M3nS nuts you've prepared earlier and insert them in the Einsy case the following way:

    • Two nuts inside the heatbed holder (note one slot is from the inside of the cover)

    • Two nuts inside the extruder cable holder.

    • Press the nuts all the way in.

    • Check the proper alignment using an Allen key.

  10. Insert four M3n nuts in nut traps. Slide EINSY inside the base and tighten it with four M3x10 screws.
    • Insert four M3n nuts in nut traps.

    • Slide EINSY inside the base and tighten it with four M3x10 screws.

    • Tighten the screws carefully, you can damage the board.

    • Use the needle nose pliers to help with positioning the screws.

  11. Holes with blue arrows will be used to mount the Einsy-base. Insert M3x10 screws in the holes and tighten them just slightly. 3-4 turns are enough for now.
    • Holes with blue arrows will be used to mount the Einsy-base.

    • Insert M3x10 screws in the holes and tighten them just slightly. 3-4 turns are enough for now.

  12. Before mounting the base on the frame, take the cable from X-axis motor (see the yellow label) and plug it in the EINSY. Push the textile sleeve in the slot and leave some slack of the cable along the board (don't stretch the cable). See the slots on the printed part, which will be used for the M3x10 screws (those are already on the frame).
    • Before mounting the base on the frame, take the cable from X-axis motor (see the yellow label) and plug it in the EINSY.

    • Push the textile sleeve in the slot and leave some slack of the cable along the board (don't stretch the cable).

    • See the slots on the printed part, which will be used for the M3x10 screws (those are already on the frame).

  13. Slide the Einsy-base on the prepared M3x10 screws and align it with the edge of the Z-axis frame. Using 2.5mm Allen key tighten both screws. See second and third picture. Using 2.5mm Allen key tighten both screws. See second and third picture.
    • Slide the Einsy-base on the prepared M3x10 screws and align it with the edge of the Z-axis frame.

    • Using 2.5mm Allen key tighten both screws. See second and third picture.

  14. In the following steps, we will manage all the cables on the printer. We've tested several ways and this seems to be the most efficient. In the upcoming steps, please tighten all zip ties carefully as you might pinch/break the cables.
    • In the following steps, we will manage all the cables on the printer. We've tested several ways and this seems to be the most efficient.

    • In the upcoming steps, please tighten all zip ties carefully as you might pinch/break the cables.

    • Turn the printer on the PSU side, then depending on the PSU type:

    • Silver PSU: the cables go above the extrusion

    • Black PSU: the cables go below the extrusion

    • This is the only difference. In all the steps, the cable management is the same for both Black and Silver PSU versions.

  15. Start with the Z-axis motor (right). Slide the zip tie through the circular holes in the frame to create a loop.
    • Start with the Z-axis motor (right).

    • Slide the zip tie through the circular holes in the frame to create a loop.

    • Push the cable gently in the zip tie and tighten it so it is snug and holding the wires. Be careful not to over tighten the tie as it can cut the wires . Cut the remaining part.

  16. Continue upwards and using another zip tie create the next loop. Insert  Z-axis cable and all cables from the PSU. Make sure all the cables are below smooth rods and not interfering with the Y-carriage.
    • Continue upwards and using another zip tie create the next loop.

    • Insert Z-axis cable and all cables from the PSU. Make sure all the cables are below smooth rods and not interfering with the Y-carriage.

    • Push the cable gently in the zip tie and tighten it so it is snug and holding the wires. Be careful not to over tighten the tie as it can cut the wires . Cut the remaining part.

  17. Continue upwards and using another zip tie create the next loop. Insert Y-axis motor cable to the bundle.
    • Continue upwards and using another zip tie create the next loop.

    • Insert Y-axis motor cable to the bundle.

    • Push the cable gently in the zip tie and tighten it so it is snug and holding the wires. Be careful not to over tighten the tie as it can cut the wires . Cut the remaining part.

  18. Take the LCD cables and gently push them in the aluminum extrusion. Leave some slack, do not stretch the cables too much. Use the whole length of the extrusion. Bend the cable bundle down for now.
    • Take the LCD cables and gently push them in the aluminum extrusion. Leave some slack, do not stretch the cables too much.

    • Use the whole length of the extrusion.

    • Bend the cable bundle down for now.

    • Carefully fold the LCD cables around the frame.

  19. Continue upwards and using another zip tie create the next loop. Take the bundle of cables and place it over the LCD cables.
    • Continue upwards and using another zip tie create the next loop.

    • Take the bundle of cables and place it over the LCD cables.

    • Push the cables gently in the zip tie (excluding the LCD cables) and tighten it. Cut the remaining part.

  20. Slide the zip tie through the circular holes in the frame to create a loop. This time place the LCD cables carefully in the zip tie. Insert the Z-axis left motor cable and all cables from the bundle.
    • Slide the zip tie through the circular holes in the frame to create a loop.

    • This time place the LCD cables carefully in the zip tie.

    • Insert the Z-axis left motor cable and all cables from the bundle.

    • Don't tighten the zip tie! Wait for the next step.

  21. Push the cables gently in the zip tie, before you tighten the zip tie, read the next point.
    • Push the cables gently in the zip tie, before you tighten the zip tie, read the next point.

    • This time be very careful! Tighten the zip tie slightly or you will damage the LCD cables! The zip tie should be snug to hold the wires in place. Over tightening it can cut the wires!

    • That's it! Cables are organised, let's connect them to the EINSY board. Now you can turn the printer back on its feet.

  22. For the following steps, please prepare:
    • For the following steps, please prepare:

    • Extruder-cable-clip (1x)

    • Heatbed-cable-clip (1x)

    • M3x10 screw (4x)

    • Note the difference between both clips.

  23. Insert the heatbed cable bundle including the textile sleeve in the Einsy-base. Make sure the sleeve is inside the holder, see the picture.
    • Insert the heatbed cable bundle including the textile sleeve in the Einsy-base.

    • Make sure the sleeve is inside the holder, see the picture.

    • Use the Heatbed-cable-clip and two M3x10 screws to fix the cable bundle in place. Note the correct orientation of the clip, try closing the door.

  24. IMPORTANT: it is CRUCIAL to connect the PSU and HB cables in correct order to the EINSY board. POSITIVE WIRE must be connected to POSITIVE SLOT. There are TWO VERSIONS of the cables with different coloring system: Version A: both wires on each pair are black, POSITIVE WIRE is  marked with a RED LINE
    • IMPORTANT: it is CRUCIAL to connect the PSU and HB cables in correct order to the EINSY board. POSITIVE WIRE must be connected to POSITIVE SLOT. There are TWO VERSIONS of the cables with different coloring system:

    • Version A: both wires on each pair are black, POSITIVE WIRE is marked with a RED LINE

    • Version B: on each pair, there is a red and black wire. POSITIVE WIRE is FULLY RED.

    • Connect wires from PSU and HEATBED to the EINSY board in the following order (red arrows indicate positive slot):

    • The first cable from the PSU (A+|A-).

    • The second cable from the PSU (B+|B-).

    • Cable from the heatbed (C+|C-).

    • Both cables (two pairs) from the PSU are the same, their order doesn't matter, just ensure correct polarity.

  25. PROPER ORIENTATION of the POWER CABLE is IMPORTANT!!! CORRECT: Bent part of the connector is facing up. Push it below the square washer, all the way in.
    • PROPER ORIENTATION of the POWER CABLE is IMPORTANT!!!

    • CORRECT: Bent part of the connector is facing up. Push it below the square washer, all the way in.

    • INCORRECT: Bent part of the connector is facing down. This will cause issues and might end up damaging the board!

  26. Please make sure you have connected  POSITIVE and NEGATIVE polarity as described in the previous step! Always place the wire with POSITIVE polarity in the positive  slot on EINSY. See the pictures for red arrows. Make sure the bent part of the cable connector is always facing up (away from the board)!!! Similar setup was used during the Black PSU assembly. Check once more following setup:
    • Please make sure you have connected POSITIVE and NEGATIVE polarity as described in the previous step! Always place the wire with POSITIVE polarity in the positive slot on EINSY. See the pictures for red arrows.

    • Make sure the bent part of the cable connector is always facing up (away from the board)!!! Similar setup was used during the Black PSU assembly.

    • Check once more following setup:

    • Take the first cable from the PSU and connect the pair of wires to the EINSY board. Use the bundled Philips screwdriver. TIGHTEN the screw firmly!

    • Take the second cable from the PSU and connect the pair of wires to the EINSY board.

    • The last pair of wires is from the heatbed. Connect them to the last two slots.

    • Please note that not following these steps correctly could possibly void the warranty on the printer if any damage occurs. Please take your time and double check the correct connections and tighten the screws.

  27. For the following step please prepare:
    • For the following step please prepare:

    • PSU-cover-Delta (1x)

    • M3x10 screw (2x)

  28. Now it is time for the final check of the power cables. Make sure you've connected the correct polarity and tightened the screws properly. Note that the PSU and Einsy board have different order of the polarities, ALWAYS look for the + / - signs! Red wire  - positive polarity (+)
    • Now it is time for the final check of the power cables. Make sure you've connected the correct polarity and tightened the screws properly.

    • Note that the PSU and Einsy board have different order of the polarities, ALWAYS look for the + / - signs!

    • Red wire - positive polarity (+)

    • Black wire - negative polarity (-)

    • Slide the cover on the cables from the top. Make sure the "PRUSA" logo is facing up.

    • Secure the cover using two M3x10 screws. Note that the holes are quite deep.

  29. Identify all motors using the yellow labels and connect them to the board. X-axis motor (already connected)
    • Identify all motors using the yellow labels and connect them to the board.

    • X-axis motor (already connected)

    • Y-axis motor

    • Z-axis motors ( the order doesn't matter)

    • Make sure the lowest connector is free (marked red). The Z axis motors have to be connected at the same level!! It is a common mistake to connect the Z-axis motors under each other.

    • Try to achieve the similar cable arrangement inside the cover to give yourself enough space to work with.

  30. Find the twisted pair (black and white | PP) cable from PSU and connect it to the board. Press the black&white cable to the left side of the cover. Arrange the cables as in the picture, so you have more space for the upcoming ones. Take the thermistor (green label | HT) from the heatbed and connect it.
    • Find the twisted pair (black and white | PP) cable from PSU and connect it to the board.

    • Press the black&white cable to the left side of the cover. Arrange the cables as in the picture, so you have more space for the upcoming ones.

    • Take the thermistor (green label | HT) from the heatbed and connect it.

    • Thermistor cable can be also in white color and missing the green label. It's polarity doesn't matter, it can be plugged both ways.

    • Try to achieve the similar cable arrangement inside the cover to give yourself enough space to work with.

  31. Find the slot for the NYLON filament, you will need it in the next step.
    • Find the slot for the NYLON filament, you will need it in the next step.

    • Slightly separate the nylon from the rest of the cables. No need to unwrap the sleeve.

    • If the nylon is hidden inside the textile sleeve, use the technique in the next step to reach it.

  32. Before we proceed further, we need to twist the textile sleeve. This will prevent the cables inside to slip out during the print.
    • Before we proceed further, we need to twist the textile sleeve. This will prevent the cables inside to slip out during the print.

    • Using your fingers gently twist the sleeve (not the cables) and create several wraps.

    • Twisting the sleeve will effectively shorten its length. In the next steps you might need to twist the sleeve slightly back to prolong it.

  33. Slide the NYLON filament in the hole. Make sure the filament isn't pushing into the motor cables, which would indicate it is too long and you need to slightly unwrap the sleeve and push the filament back. Slide the sleeve in the holder at least 3/4 of the holder's height.
    • Slide the NYLON filament in the hole.

    • Make sure the filament isn't pushing into the motor cables, which would indicate it is too long and you need to slightly unwrap the sleeve and push the filament back.

    • Slide the sleeve in the holder at least 3/4 of the holder's height.

    • Again, ensure the filament isn't pushing the motor cables and if needed slightly unwrap the sleeve and push the filament up.

    • Use the Extruder-cable-clip and two M3x10 screws to fix the cable bundle in place.

  34. IMPORTANT: Connecting the filament sensor cable properly is crucial. If you don't follow the instructions properly, you will burn the sensor!!! DON'T CONNECT THE CABLE NOW, wait for the next step!!! To ensure the cable is connected properly we are introducing a new part called "plug-aligner", which is now distributed with all MK3S printers leaving the factory.
    • IMPORTANT: Connecting the filament sensor cable properly is crucial. If you don't follow the instructions properly, you will burn the sensor!!!

    • DON'T CONNECT THE CABLE NOW, wait for the next step!!!

    • To ensure the cable is connected properly we are introducing a new part called "plug-aligner", which is now distributed with all MK3S printers leaving the factory.

    • In case the plug-aligner falls out during the transport, gently push it back in. The notch should be oriented up, like in the picture.

    • There are two rows of pins in the connector:

    • Lower row (for MK3S) use these pins to connect the IR-sensor.

    • Upper row (for MMU2S) these pins won't be used in this manual.

    • STL file for the plug-aligner is available in the MK3S package at prusa3d.com/prusa-i3-printable-parts/

  35. Connect the remaining cables from the Extruder: Extruder heater (red cable pair | Nr. 1)
    • Connect the remaining cables from the Extruder:

    • Extruder heater (red cable pair | Nr. 1)

    • Hotend fan (black cable | Nr .2)

    • Print fan (red label | Nr. 3)

    • IR-sensor with two wires facing to the right (Nr. 4) !!! USE THE BOTTOM ROW, leave the upper row free!!!

    • Extruder motor (yellow label with "E" | Nr. 5)

    • Extruder thermistor (green/yellow label | Nr. 6)

    • P.I.N.D.A. probe cable (Nr. 7)

  36. LCD cable with ONE stripe (Connector P1) LCD cable with TWO stripes (Connector P2)
    • LCD cable with ONE stripe (Connector P1)

    • LCD cable with TWO stripes (Connector P2)

    • The pink stripe on the LCD cables should be facing upwards.

  37. Check your electronics connection with the attached picture. Make sure once more the Filament sensor cable is connected to all pins! Misalignment might lead to permanently damaging the sensor.
    • Check your electronics connection with the attached picture.

    • Make sure once more the Filament sensor cable is connected to all pins! Misalignment might lead to permanently damaging the sensor.

  38. For this step, please prepare: M3x40 screw (1x)
    • For this step, please prepare:

    • M3x40 screw (1x)

    • Close the Einsy-door.

    • Make sure that no wire is pinched!

    • Tighten the M3x40 screw.

  39. If you've assembled the feet in the second chapter, you can skip this step. Antivibration feet (4x)
    • If you've assembled the feet in the second chapter, you can skip this step.

    • Antivibration feet (4x)

    • Turn the frame on its side and insert the antivibration foot, then rotate with the foot until you squish the rim inside the extrusion.

    • Repeat this process on all 4 feet. Place them 2-3 cm from the end of each extrusion.

  40. For the following steps, please prepare:
    • For the following steps, please prepare:

    • Centre part (1x)

    • Side arm (2x)

  41. Don't use excessive force during the assembly, or you might damage the spool holder locking system. Place all three parts in front of you. Note both "arms" are identical. Make sure the C shaped part, which will snap on the printer's frame is facing towards you. Take the "arm" on the right side, insert it gently in the main part and start to rotate clockwise (away from you). It should take about half the turn to lock the part in place.
    • Don't use excessive force during the assembly, or you might damage the spool holder locking system.

    • Place all three parts in front of you. Note both "arms" are identical. Make sure the C shaped part, which will snap on the printer's frame is facing towards you.

    • Take the "arm" on the right side, insert it gently in the main part and start to rotate clockwise (away from you). It should take about half the turn to lock the part in place.

    • Take the "arm" on the left side, insert it gently in the main part and start to rotate anticlockwise (towards you). It should take about half the turn to lock the part in place.

    • The assembly requires a very small force (torque). If you experience issues, check first the locking mechanism for obstacles.

  42. To properly mount the spool holder, let the "tooth" sit on the frame (in the middle) and then press in the direction of the arrows (push backwards, while slightly pressing downwards). Don't try to assemble spool holder by pushing it only from the top. More force is needed and you may damage the holder. Don't try to assemble spool holder by pushing it only from the top. More force is needed and you may damage the holder.
    • To properly mount the spool holder, let the "tooth" sit on the frame (in the middle) and then press in the direction of the arrows (push backwards, while slightly pressing downwards).

    • Don't try to assemble spool holder by pushing it only from the top. More force is needed and you may damage the holder.

  43. Phew! That was a lot of work to do. Eat 15 % of the bears.
    • Phew! That was a lot of work to do. Eat 15 % of the bears.

  44. Congratulations, you've just assembled the Original Prusa i3 MK3S 3D printer!
    • Congratulations, you've just assembled the Original Prusa i3 MK3S 3D printer!

    • You're almost there... Just finish the chapter 9. Preflight check

Finish Line

1096 other people completed this guide.

Jakub Dolezal

Member since: 02/20/2017

224 Guides authored

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Prusa Research Member of Prusa Research

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17 Comments

Make the ensie board box symmetrical with the power supply. Ribbon cables instead of screw terminals. Good job guys! Thanks!

Richard Perkins - Reply

Hi! The instructions have been superb and extremely clear. Thanks for being so meticulous.

I have found, though, that the cables in mine were a bit too long and I had to bunch them up in the Einsy Box and struggled to close it because it was so full. Maybe I did something wrong at some point?

ISF - Reply

Hello, thank you for your kind words! No worries, this is quite normal, don’t be afraid to cram the cables a little bit when closing the Einsy box .

Martin L. - Official Prusa CS -

I just let the extra hang out the bottom, making sure it wouldn’t catch on anything. The E wire was just slightly too short, but some squirming it around inside the cloth sheath made it reach. Barely.

Darrell -

No more Haribo :(

Mario Theodoridis - Reply

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