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

    • 3mm Allen key for M5 screws

    • 2.5mm Allen key for M3 screws

    • 2mm Allen key for nut alignment

  2. Prepare following parts to build the YZ frame: Aluminum extrusions (4x)
    • Prepare following parts to build the YZ frame:

    • Aluminum extrusions (4x)

    • Aluminum frame (1x)

    • M5x16r screw (16x)

    • You can tighten the M5x16r with included Allen key or with a Torque Wrench. Recommended torque is 4.5 N.m (40 lb-in).

  3. Take the LONGER aluminum extrusions and place them next to the frame. Make sure the engraved PRUSA logo on the frame (top left) IS  VISIBLE! Note: screws are inserted from the opposite side of the frame. If you need to manipulate with the frame, make sure the extrusions are on the correct side.
    • Take the LONGER aluminum extrusions and place them next to the frame.

    • Make sure the engraved PRUSA logo on the frame (top left) IS VISIBLE!

    • Note: screws are inserted from the opposite side of the frame. If you need to manipulate with the frame, make sure the extrusions are on the correct side.

    • Ensure you are using the correct holes, see the second picture. Use the M5 screws to connect extrusions to the frame. Tighten the screws with the Allen key just slightly!

    • Now, tighten the screws fully, but ON A DIAGONAL, see the last picture. As soon as you finish the first, tighten the second pair. Then proceed to the second long extrusion.

  4. Take the SHORTER aluminum extrusions and place them next to the frame. Short extrusions must be placed on the side, where engraved PRUSA logo on the frame (top left) IS NOT VISIBLE. Note: screws are inserted from the opposite side of the frame. If you need to manipulate with the frame, make sure the extrusions are on the correct side.
    • Take the SHORTER aluminum extrusions and place them next to the frame.

    • Short extrusions must be placed on the side, where engraved PRUSA logo on the frame (top left) IS NOT VISIBLE.

    • Note: screws are inserted from the opposite side of the frame. If you need to manipulate with the frame, make sure the extrusions are on the correct side.

    • Ensure you are using the correct holes, see the second picture. Use the M5x16 screws to connect extrusions to the frame. Tighten the screws just slightly!

    • Now, tighten the screws fully, but ON A DIAGONAL, see the last picture. As soon as you finish the first, tighten the second pair. Then proceed to the second short extrusion.

  5. Before we proceed further, let's make a final check. IT IS VERY IMPORTANT to have extrusions on the correct side of the frame.
    • Before we proceed further, let's make a final check. IT IS VERY IMPORTANT to have extrusions on the correct side of the frame.

    • Long extrusions - must be on the side of the frame with the Prusa logo, also ensure longer extrusions are closer together.

    • Short extrusions - must be on the side of the frame without the Prusa logo, also ensure shorter extrusions are further away from each other.

  6. Prepare following parts to assemble the front and rear plates:
    • Prepare following parts to assemble the front and rear plates:

    • Front plate (1x)

    • Rear plate (1x)

    • M5x16r screw (16x)

    • You can tighten the M5x16r with included Allen key or with a Torque Wrench. Recommended torque is 4.5 N.m (40 lb-in).

  7. Rotate the frame with longer extrusions towards you. Place the front plate on the extrusions and secure it with M5x16r screws, DON'T TIGHTEN them yet!
    • Rotate the frame with longer extrusions towards you.

    • Place the front plate on the extrusions and secure it with M5x16r screws, DON'T TIGHTEN them yet!

    • Now, tighten the screws fully, but ON A DIAGONAL, see the second picture. As soon as you finish the first, tighten the second pair. Then proceed to the second long extrusion.

  8. This is a very IMPORTANT step! Incorrect placement of PSU holders will lead to issues later. For the following step please prepare: PSU holders M3nE (2x)
    • This is a very IMPORTANT step! Incorrect placement of PSU holders will lead to issues later.

    • For the following step please prepare:

    • PSU holders M3nE (2x)

    • Take the YZ frame and rotate it with the shorter extrusions towards you.

    • Place the PSU holders in the extrusion, ensure it is the correct extrusion. See the picture.

    • The exact position of the PSU holders doesn't matter, we will adjust them later.

  9. Ensure the frame with shorter extrusions is rotated towards you. Place the rear plate on the extrusions and secure it with M5x16r screws, DON'T TIGHTEN them yet!
    • Ensure the frame with shorter extrusions is rotated towards you.

    • Place the rear plate on the extrusions and secure it with M5x16r screws, DON'T TIGHTEN them yet!

    • Now, tighten the screws fully, but ON A DIAGONAL, see the second picture. As soon as you finish the first, tighten the second pair. Then proceed to the second short extrusion.

  10. Before you proceed further, please place the frame on a FLAT SURFACE (this is crucial). All the components are cut or drilled by machine for highest precision, but with uneven tightening, it is possible to warp the frame.
    • Before you proceed further, please place the frame on a FLAT SURFACE (this is crucial).

    • All the components are cut or drilled by machine for highest precision, but with uneven tightening, it is possible to warp the frame.

    • Using your hand, try to wiggle with the frame sides and check, whether some corners are lifting up or not.

    • In case you find some imperfections, release the screws, press the extrusions against the FLAT SURFACE and tighten them again.

  11. Note this step is optional for now. We recommend mounting the feet to protect the surface on your table (workbench). However, you need to lift the frame up before each turn. There will be extra step at the end of the assembly to remind you of the antivibration feet. Antivibration feet (4x)
    • Note this step is optional for now. We recommend mounting the feet to protect the surface on your table (workbench). However, you need to lift the frame up before each turn.

    • There will be extra step at the end of the assembly to remind you of the antivibration feet.

    • Antivibration feet (4x)

    • Turn the YZ frame on the side and insert the antivibration foot inclined, then rotate 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.

  12. ATTENTION: Starting 01/2018 Y-holder-front and Y-holder-back parts are replaced by Y-rod-holder, which has the same shape for all 4 pieces. Please see the second picture. Nut insertion and tightening procedure remains the same. For the following steps, please prepare:
    • ATTENTION: Starting 01/2018 Y-holder-front and Y-holder-back parts are replaced by Y-rod-holder, which has the same shape for all 4 pieces. Please see the second picture. Nut insertion and tightening procedure remains the same.

    • For the following steps, please prepare:

    • Y-holder-front (2x)

    • Y-holder-back (2x)

    • M3x10 screw (8x)

    • M3nS nut (8x)

  13. Take the Y-holder-front and insert M3nS nuts. Make sure you've pressed the nuts all the way in. In case you can't press the nuts in, don't use excessive force. First, check if there isn't any obstacle in the nut trap.
    • Take the Y-holder-front and insert M3nS nuts.

    • Make sure you've pressed the nuts all the way in.

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

    • Ensure and adjust the alignment of each nut with the 2mm Allen key.

    • Repeat this step for the remaining Y-holders. At the end, you should have two pairs, front and back.

  14. First, take the Y-holder-front parts and place them on the longer extrusions, openings for screws must be facing up. Rotate the 3D printed parts towards the front plate. Secure each front holder with two M3x10 screws. Tighten both screws equally, but not completely. We will tighten them fully later on.
    • First, take the Y-holder-front parts and place them on the longer extrusions, openings for screws must be facing up.

    • Rotate the 3D printed parts towards the front plate.

    • Secure each front holder with two M3x10 screws. Tighten both screws equally, but not completely. We will tighten them fully later on.

    • Second, take the Y-holder-back parts and secure them with M3x10 screws on the rear plate (with shorter extrusions). Tighten both screws equally, but not completely. We will tighten them fully later on.

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

    • Y-belt-idler (1x)

    • M3x18 screw (1x)

    • M3x10 screw (2x)

    • M3nN nyloc nut (3x)

    • 623h bearing housing (1x)

  16. Take the Y-belt-idler and insert two M3nN nyloc nuts from the  top. The rubber inside nuts must be facing up. Turn the idler to the other side and insert the last M3nN nyloc nut. The rubber inside the nut must be facing towards you.
    • Take the Y-belt-idler and insert two M3nN nyloc nuts from the top. The rubber inside nuts must be facing up.

    • Turn the idler to the other side and insert the last M3nN nyloc nut. The rubber inside the nut must be facing towards you.

    • Make sure all three nuts are all the way in.

    • In case you can't press the nuts in, don't use excessive force. Take M3 screw thread it from the opposite side of the printed part, as you tighten the screw, it will pull the nut in. Be careful not to break the idler during tightening.

  17. Insert the prepared bearing in the Y-belt-idler. Bearing housing orientation doesn't matter.
    • Insert the prepared bearing in the Y-belt-idler.

    • Bearing housing orientation doesn't matter.

    • Secure the bearing with the M3x18 screw. Don't fully tighten the screw.

    • Place your finger on the bearing and ensure it can rotate freely. If needed adjust the screw.

  18. Rotate the frame with longer extrusions towards you. Take the Y-belt-idler and place it on the front plate. Note there is a mark (circle) on the printed part facing up. Secure the Y-belt-idler with two M3x10 screws.
    • Rotate the frame with longer extrusions towards you.

    • Take the Y-belt-idler and place it on the front plate. Note there is a mark (circle) on the printed part facing up.

    • Secure the Y-belt-idler with two M3x10 screws.

    • DON'T TIGHTEN the screws fully, you will need a "loose" Y-belt-idler to adjust the tension in the belt later on.

  19. For the following steps, please prepare: Y-axis motor (1x)
    • For the following steps, please prepare:

    • Y-axis motor (1x)

    • Y-motor-holder (1x)

    • M3x10 screw (4x)

    • M3n nut (2x)

    • Ensure you are using the correct motor, there is a label on the bottom of the casing. The reason is, each motor has different cable length.

  20. Take the Y-motor-holder and insert two M3n nuts. In case you can't press the nuts in, don't use excessive force. Use an M3 screw from the other side and tighten it. Place the Y-motor-holder on the motor, ensure the correct orientation as in the picture.
    • Take the Y-motor-holder and insert two M3n nuts.

    • In case you can't press the nuts in, don't use excessive force. Use an M3 screw from the other side and tighten it.

    • Place the Y-motor-holder on the motor, ensure the correct orientation as in the picture.

    • Using two M3x10 screws tighten holder and motor together.

  21. Take the Y-motor-holder and place it on the rear plate (short extrusions).
    • Take the Y-motor-holder and place it on the rear plate (short extrusions).

    • Ensure correct orientation, the motor shaft must be facing towards PSU holders.

    • Secure Y-motor-holder with two screws M3x10.

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

    • Y-carriage (1x)

    • Y-belt-holder (1x)

    • U-bolt (3x)

    • Linear bearing (3x)

    • M3nN nyloc nut (6x)

    • M3x10 screw (2x)

    • For MK2/S owners, the Y-carriage is now symmetrical in one direction, therefore the dot (countersink, marker) orientation for bearing insertion doesn't matter.

  23. When placing bearings onto the Y-carriage, make sure that they are oriented as shown in the picture. One of the tracks (row of balls) has to be in line with the cutout for the bearing!
    • When placing bearings onto the Y-carriage, make sure that they are oriented as shown in the picture. One of the tracks (row of balls) has to be in line with the cutout for the bearing!

    • This orientation has to be followed in all 3 bearings on the Y-carriage!

  24. This is VERY IMPORTANT part of the assembly, which can significantly influence printer's behaviour. PLEASE read following lines carefully! Place the Y-carriage on a flat surface. Orientation doesn't matter. Insert linear bearing in the cutout and secure it by U-bolt.
    • This is VERY IMPORTANT part of the assembly, which can significantly influence printer's behaviour. PLEASE read following lines carefully!

    • Place the Y-carriage on a flat surface. Orientation doesn't matter.

    • Insert linear bearing in the cutout and secure it by U-bolt.

    • Hold thumb on the U-bolt and turn the carriage. Place nyloc nuts on both ends of the U-bolt.

    • Start tightening the nuts, BUT ENSURE you are tightening both nuts equally and AS SOON AS EACH NUT REACHES THE SURFACE OF THE Y-CARRIAGE STOP TIGHTENING!!! We will finish tightening the nuts in the next step.

    • Repeat these steps for the remaining two linear bearings.

    • Over tightening nuts leads to deformation of the bearing and all the issues connected with it. Please follow the instructions.

  25. Ensure again the nuts are tightened just to the surface and equally. Check if the bearing is centered in both directions, if not slightly release the nuts and adjust its position. Then retighten the nuts to the previous state.
    • Ensure again the nuts are tightened just to the surface and equally.

    • Check if the bearing is centered in both directions, if not slightly release the nuts and adjust its position. Then retighten the nuts to the previous state.

    • When you are ready, using pliers rotate each nut, but only 90°. This is enough to fix the bearing without deforming it.

    • Repeat these steps for remaining two linear bearings.

  26. Place the Y-belt-holder on the Y-carriage. ENSURE THE TEETH are facing TWO BEARINGS!
    • Place the Y-belt-holder on the Y-carriage. ENSURE THE TEETH are facing TWO BEARINGS!

    • Secure the Y-belt-holder with two M3x10 screws. Tighten them fully, there are threads in the Y-carriage.

  27. Take all the smooth rods and compare their lengths. For  Y-carriage you need mid-sized rods (330 mm). NOW, PLEASE BE VERY CAREFUL! Gently insert the rod straight into the bearings, do not apply too much force and do not tilt the rod!
    • Take all the smooth rods and compare their lengths. For Y-carriage you need mid-sized rods (330 mm).

    • NOW, PLEASE BE VERY CAREFUL! Gently insert the rod straight into the bearings, do not apply too much force and do not tilt the rod!

    • If you can't slide the smooth rod easily, check the two bearings are aligned properly.

    • 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.

  28. Take the Y-carriage including smooth rods and place them in YZ-frame. Make sure, that two bearings are on the left side (see the picture). Using your thumb, press the smooth rods inside all four holders. Don't use excessive force.
    • Take the Y-carriage including smooth rods and place them in YZ-frame. Make sure, that two bearings are on the left side (see the picture).

    • Using your thumb, press the smooth rods inside all four holders. Don't use excessive force.

    • Check again the correct bearing orientation!!!

  29. Find the package with zip ties and take out 4 pieces. Slide the zip tie through the holder, there is a slot. Connect the zip tie and tighten it. The "head" should be inside the frame.
    • Find the package with zip ties and take out 4 pieces.

    • Slide the zip tie through the holder, there is a slot.

    • Connect the zip tie and tighten it. The "head" should be inside the frame.

    • Using pliers cut the remaining part.

    • Repeat this step in all four corners.

  30. IMPORTANT: proper alignment of the smooth rods is crucial to reduce noise and overall friction. Ensure all M3x10 screws on Y-holders are released, so the printed parts are able to move. Move the Y-carriage back and forth across the entire length of the smooth rods to align them.
    • IMPORTANT: proper alignment of the smooth rods is crucial to reduce noise and overall friction.

    • Ensure all M3x10 screws on Y-holders are released, so the printed parts are able to move.

    • Move the Y-carriage back and forth across the entire length of the smooth rods to align them.

    • Then move the carriage to the front plate and tighten all screws in the front-Y-holders.

    • Move the Y-carriage to the rear plate and tighten all screws in the back-Y-holders.

  31. There is a flat part on the motor shaft, rotate it similarly to the first picture. Place a GT2-16 pulley on the Y-motor shaft as shown in the picture. Don't press the pulley against the motor. Leave a gap so the pulley can rotate freely.
    • There is a flat part on the motor shaft, rotate it similarly to the first picture.

    • Place a GT2-16 pulley on the Y-motor shaft as shown in the picture.

    • Don't press the pulley against the motor. Leave a gap so the pulley can rotate freely.

    • One of the screws must be facing directly against the pad (flat part) on the shaft. Slightly tighten the first screw.

    • Turn the shaft and slightly tighten the second screw.

    • Don't tighten the pulley firmly yet, we'll get to that later.

  32. Turn the frame on its "right" side, as shown in the picture. You need access to belt holder, idler and pulley. Use the bottom opening in the extrusion and gently insert the cable from Y-motor. DON'T TRIM THE BELT unless you are asked in the instructions!!!
    • Turn the frame on its "right" side, as shown in the picture. You need access to belt holder, idler and pulley.

    • Use the bottom opening in the extrusion and gently insert the cable from Y-motor.

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

    • Find the belt for Y-axis (Y-GT2 650 mm) and insert one end in the Y-belt-holder. Ensure you are using the upper slot (closer to Y-carriage).

    • Make sure you won't accidentally use the belt for X-axis (X-GT2), which is longer.

    • Press the belt all the way in, use Allen key.

  33. Insert the belt through the idler as shown in the picture. Guide the belt behind Y-axis motor and ensure following: Don't use the second slot in the Y-belt-holder.
    • Insert the belt through the idler as shown in the picture.

    • Guide the belt behind Y-axis motor and ensure following:

    • Don't use the second slot in the Y-belt-holder.

    • Guide the belt above the aluminum Z frame, NOT below.

    • Guide the belt above the rear plate, NOT below.

    • Turn the printer on its "feet" and guide the belt around Y-motor.

  34. Turn the printer back on the side. Hold the Y-carriage by hand (prevent its movement) as we need to pull the belt. Ensure the idler isn't tightened completely to the front plate. Otherwise, you won't be able to adjust the tension later.
    • Turn the printer back on the side. Hold the Y-carriage by hand (prevent its movement) as we need to pull the belt.

    • Ensure the idler isn't tightened completely to the front plate. Otherwise, you won't be able to adjust the tension later.

    • Take the end of the belt, pull the belt with a reasonable force and insert it in the Y-belt-holder. Note you don't have to use the whole length of the slot.

    • Press the belt all the way in, use Allen key.

    • The belt should be stretched and not easily bent. However, the final tension will be adjusted later.

  35. Make sure the belt is placed in the "axis" of the printer. Both top and bottom part of the belt should be parallel (above each other). To adjust the belt position, release screws on the pulley and slightly move with it, until you reach the best position.
    • Make sure the belt is placed in the "axis" of the printer. Both top and bottom part of the belt should be parallel (above each other).

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

    • In case you can't make the belt parallel, check if the belt is properly inserted in the Y-belt-holder (below Y-carriage).

    • Tighten both screws on the pulley.

  36. Using Allen key tighten/release the screws on the front plate. Try to adjust both screws the same way.
    • Using Allen key tighten/release the screws on the front plate. Try to adjust both screws the same way.

    • 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.

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

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

    • Move the Y-carriage with your hand towards the Y-axis motor. Don't use excessive force.

    • If the belt is stretched properly, you should feel a resistance and the Y-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.

  38. Y-axis is done, great job! Open the bag with Haribo gummy bears and treat yourself with few ;)
    • Y-axis is done, great job! Open the bag with Haribo gummy bears and treat yourself with few ;)

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

    • Ready for more? Lets move to 3. X-axis assembly

Finish Line

1077 other people completed this guide.

Jakub Dolezal

Member since: 02/20/2017

214 Guides authored

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Prusa Research Member of Prusa Research

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355 Guides authored

77 Comments

I am left with 2 extra M3n nuts (hexagons)

Alex Tramiel - Reply

Hi Alex, thanks for the feedback. For this chapter you need two M3n nuts to place them in the Y-motor-holder.

Jakub Dolezal -

Same here, two extra nuts.

Scott -

I also have 2 extra M3n nuts.

Brandon Oprendek -

Same here, two extra M3 standard nuts. All nuts are properly inserted in the printed parts, no screws are lacking nuts. Maybe can be put on the opposite side of the y-carriage to lock in the bolts holding the Y belt holder? Not necessary, but maybe optional?

Kaina Cockett -

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