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Replacing Parts on the X/Y Axis

These instructions are applicable to all models in the UM2 and UM3 family. We suggest leaving the protective glass plate on your heated bed while performing maintenance, or putting a place of piece of cardboard down, to protect your heated bed plate in case anything is dropped during disassembly or reassembly. All photos are of the UM2; the UM3 disassembly and reassembly follow the same instructions. The UM3 XY axes have 3mm spacers in place of the 5mm spacers, and 8mm spacers in place of the 10mm spacers.

There is a separate page for replacing endstops. You can find it here

Long Belts 

  1. Push/tilt the black plastic blocks that hold the printhead shafts in place to pop the printhead shafts out. Holding the print head AND both cross bars, rotate the assembly so the shafts are on the diagonal and lift them out of the printer. While working, take care with the nozzle. Even a short drop can damage the tip. Once the print head is out of the machine, remove the cross bars. We suggest wrapping the print head in a towel or bubble wrap to protect it from damage while it is outside the machine.    
  2. If you ARE replacing the short belts: remove the corner cable covers. Each cable cover is held on by one screw on the side panel, and one on the back panel. You can find a screw diagram here. If you have a UM2Go, the corner covers pop into and out of place. Unscrew the four screws that hold on each axis motor (X motor and Y motor). The motors are located on the back panel and the left panel. Make sure you hold the motor when you undo the screws or the motor will fall. Set the motors in the bottom of the printer. Replacing the motors is one of the last steps. 
  3. If you ARE NOT replacing the short belts: loosen (do not remove) the four screws that hold on each axis motor (X motor and Y motor). The motors are located on the back panel and the left panel.You can find a screw diagram here. Raise the motor up and retighten the screws. At this point, there should be no tension on the short belts connecting the motors to the axis rods. 
  4. Loosen the set screws on the pulleys on two rods that go front to back. There is no need to completely remove the screw. If you cannot access a set screw, manually move the black sliding blocks to rotate the pulleys. Remove the two rods by pushing them through the back panel. Remove the black spacers and pulleys as you go. The left rod has two spacers and two pulleys. The right rod has two spacers and three pulleys.
  5. The remaining rods are easier to access now that the first pair of rods is out of the machine. Loosen the set screws on the pulleys on the two rods that run horizontally. There is no need to completely remove the screw. If you cannot access a set screw, manually move the black sliding blocks to rotate the pulleys. Remove the two rods by pushing them through either side panel. Remove the black spacers and pulleys as you go. There are two pulleys and one spacer on the back rod. There are two pulleys and two spacers on the front rod.
  6. You should have the following loose pieces once the rods are removed: (8) single pulleys; (1) double pulley; (1) 25mm black spacer; (4) 10mm black spacers; (2) 5mm black spacers; and (4) black sliding blocks attached to the long belts. If you are replacing the short belts, you will have (2) loose short belts as well. Set aside the old/defective parts and replace them with the new ones before beginning to reassemble the X/Y axes. If you find that you are missing a piece, check underneath the bed or underneath the printer itself. The spacers have a tendency to fall and roll.      
  7. Each hole for the rods has a bearing on the inside of the panel. Before reassembling, ensure the bearings are fully seated. The silver lip of the bearing should sit flush against the panel.
  8. To reassemble the axes, begin with one of the shorter rods. This is the back rod. Insert the rod through the left panel. Add the following to the rod: the double pulley (with the short belt on the left half, and a long belt hanging on the right half); skewer a sliding block; a single pulley (set screw toward the right panel, with a long belt hanging); and a 10mm black spacer. Once the rod is seated in both panels, push the double pulley to the left panel and the single pulley and spacer to the right panel. 
  9. Take the other short rod. This is the front rod. Insert the rod through the left panel. Add the following to the rod: 10mm black spacer; single pulley (set screw toward the left panel, long belt from the double pulley stretched across); skewer the last sliding block; single pulley (set screw toward the right panel, long belt from the single pulley stretched across); and a 10mm black spacer. Once the rod is seated in both panels, push the pulleys and spacers to their respective corners. 
  10. Now align and secure the axis. Hold the back, right pulley toward the panel and tighten the set screw. Repeat in the front, left corner. Manually move both sliding blocks to the front of the printer. Move one sliding block to rotate the pulleys until the set screw in the back, left pulley is accessible. The sliding blocks should be moving in tandem. Push the back rod toward the right which holding the double pulley to the left. Tighten the set screw on the double pulley. Grip the rod and try to move it left to right. If the pulleys are tightened correctly, the rod won't move. If the rod moves, loosen the pulley and try again. Repeat the process with the front rod, this time moving the rod to the left and the pulley to the front right corner. Once you are finished and both rods are tightly in place, move the sliding blocks to the front of the printer again. The gap between the black block and the silver pulley should be the same on the left and right sides of the machine. 
  11. One of the longer rods will be the left rod. Insert it through the back panel. Add the following to the rod: 25mm black spacer; single pulley (with the set screw toward the back panel, with the loose back belt over it); skewer the sliding block on the front-to-back belt; single pulley (with the set screw toward the front panel, with the loose front belt over it); and 5mm black spacer.
  12. The remaining rod is the right rod. Insert it through the back panel. Add the following to the rod: single pulley (set screw away from the back panel, with the short belt); 10mm black spacer; single pulley (set screw toward the back panel, back long belt stretched across); skewer the sliding block on the front-to-back belt; single pulley (with the set screw toward the front panel, front long belt stretched across); and 5mm black spacer.
  13. Now align and secure the axis. Pull the left rod toward the front and hold the front, left pulley toward the panel. Tighten the set screw. Pull the right rod toward the front, hold both back, right pulleys toward the back panel, and tighten both set screws. Manually move both sliding blocks to the right side of the printer. Move one sliding block to rotate the back, left pulley until the set screw is accessible. The sliding blocks should be moving in tandem. Pull the left rod toward the front, push the back pulley toward the panel, and tighten the set screw. Grip the rod and try to move it front to back. If the pulleys are tightened correctly, the rod won't move. If the rod moves, loosen the pulley and try again. Repeat the process with the right rod, still moving the rod to front and the pulley to the front right corner. Once you are finished and both rods are tightly in place, move the sliding blocks to the right of the printer again. The gap between the black block and the silver pulley should be the same at the front and back of the machine. 
  14. If you REMOVED the motors: loosely mount the motors back on the printer. Put the top two screws (with washers) through the panel and the black motor spacer. The spacer should be oriented so the hook is down. Hook the short belt on the pulley located on the motor while making sure the belt stays placed on the rod pulley. Orient the motor so the cord is down. Start the two top screws. Secure the cord behind the hook and start the bottom two screws. Proceed to step 15.
  15. If the motors are ON your printer: make sure the screws holding the motor are loose enough that you can freely move the motor up and down. Hold the motor level with the bottom panel. Press down on the center of the motor block to put tension on the short belt. Tighten the four screws holding the motor. 
  16. Manually move the sliding blocks and watch the short belt. If the belt moves smoothly, the motor is correctly positioned. If the short belt is loose or wobbly, loosen the motor and try again. 
  17. To seat the hot end back inside the printer, the longer printhead shaft should go through the bearing running left to right, and the shorter one, front to back. 

    You can put them both in the printhead and turn the whole head diagonally to maneuver it into the machine. The shafts fit into the black blocks as a push fit and may require a little force. Make sure the left-to-right shaft is seated far enough to the left to trigger the red Y-endstop without scraping the wall. The front-to-back shaft should be even with the back of the rear block--putting it too far back will cause it to hit the Z-shafts. Try to keep the black blocks straight when pushing them in.

If you experience slanting prints after working on your belts, look for loose pulleys.


Short Belts Only

  1. Remove the corner cable covers. Each cable cover is held on by one screw on the side panel, and one on the back panel. You can find a screw diagram here. If you have a UM2Go, the corner covers pop into and out of place. Unscrew the four screws that hold on each axis motor (X motor and Y motor). The motors are located on the left panel and the back panel. Make sure you hold the motor when you undo the screws or the motor will fall. Set the motors in the bottom of the printer.
  2. Loosen the set screws on the two pulleys on the back rod which runs horizontally.  Dislodge the rod from the left panel by moving it to the right. Put a new short belt in place of the old one. There is no need to remove the pulley to accomplish this. Settle the rod back into the left panel making sure the long belt is still over both pulleys. Hold the back right pulley toward the panel and tighten the set screw. Manually move the print head to the front of the printer. The gap between the black block and the silver pulley should be the same on the left and right sides of the machine. If the gap is the same, tighten the back rod by holding to rod toward the right and the double pulley toward the left panel and tightening the set screw before moving to step four. If the gap is different, loosen the front right pulley and align the axis in step three.
  3. Manually move both sliding blocks to the front of the printer. Move the print head to rotate the pulleys until the set screw in the back, left pulley is accessible. The sliding blocks should be moving in tandem. Push the back rod toward the right which holding the double pulley to the left. Tighten the set screw on the double pulley. Grip the rod and try to move it left to right. If the pulleys are tightened correctly, the rod won't move. If the rod moves, loosen the pulley and try again. Repeat the process with the front rod, this time moving the rod to the left and the pulley to the front right corner. Once you are finished and both rods are tightly in place, move the sliding blocks to the front of the printer again. The gap between the black block and the silver pulley should be the same on the left and right sides of the machine. 
  4. Loosen the three pulleys on the right rod. Move the rod through the back panel. Collect the pulleys and spacers as you go. You can leave the final pulley in place. Change out the short belts. Reinsert the rod replacing the pulleys and spacers as you go. Single pulley (set screw away from the back panel, with the short belt); 10mm black spacer; single pulley (set screw toward the back panel, back long belt stretched across); skewer the sliding block on the front-to-back belt; single pulley (with the set screw toward the front panel, front long belt stretched across); and 5mm black spacer. Hold the rod forward and push the two rear pulleys toward the back panel. Tighten the set screws on both pulleys. Loosen the set screw on the back left pulley. 
  5. Manually move both sliding blocks to the right side of the printer. Move one sliding block to rotate the back, left pulley until the set screw is accessible. The sliding blocks should be moving in tandem. Pull the left rod toward the front, push the back pulley toward the panel, and tighten the set screw. Grip the rod and try to move it front to back. If the pulleys are tightened correctly, the rod won't move. If the rod moves, loosen the pulley and try again. Repeat the process with the right rod, still moving the rod to front and the pulley to the front right corner. Once you are finished and both rods are tightly in place, move the sliding blocks to the right of the printer again. The gap between the black block and the silver pulley should be the same at the front and back of the machine. 
  6. Loosely mount the motors back on the printer. Put the top two screws (with washers) through the panel and the black motor spacer. The spacer should be oriented so the hook is down. Hook the short belt on the pulley located on the motor while making sure the belt stays placed on the rod pulley. Orient the motor so the cord is down. Start the two top screws. Secure the cord behind the hook and start the bottom two screws. Make sure the screws holding the motor are loose enough that you can freely move the motor up and down. Hold the motor level with the bottom panel. Press down on the center of the motor block to put tension on the short belt. Tighten the four screws holding the motor.
  7. Manually move the print head and watch the short belt. If the belt moves smoothly, the motor is correctly positioned. If the short belt is loose or wobbly, loosen the motor and try again. 

If you experience slanting prints after working on your belts, look for loose pulleys.

X-Motor

  1. Remove the corner cable cover over the x-motor. The screws are located one on the right panel and one on the back panel. Remove the cover while the bed is down to avoid damage. Remove the black ferrite core; it unsnaps.
  2. Raise the bed and lay the printer on its back. This will not damage the standard feeder. To avoid panel damage, you may want to first lay down a clean piece of cardboard or a towel. Remove the two screws that hold the electronics cover. You will need to hold the corresponding lock nuts with either pliers or a nut driver.
  3. Unplug the wire for the motor in port "X". The motor wires are on the right side of the board.
  4. Undo the four screws that hold the z-motor on. These screws come down through the bottom panel. This will move the entire bed assembly. You only need to move the motor enough to access the recess behind it.
  5. Pull the old motor wire up into the printer. Gently set the new motor in the printer and bring the cord down through the bottom panel. Maneuver the cord behind the z-screw and plug it in. 
  6. Holding the motor cord and the black z-stop cord completely in the recess, reseat the z-motor and tighten the screws. Be careful not to pinch the wires between the motor block and the panel. If the wires are completely in the recess, they will remain in tact. 
  7. Replace the electronics cover. Position the black ferrite core next to the electronics board. Make sure the flat cable and red/black LED cord are in the cut out in the top left of the cover. Screw the cover in place.
  8. Set your printer upright. Remove the four screws securing the x-motor. Hold the motor in your hand while working to avoid dropping it in the printer. Take the motor completely out of the machine.
  9. You will need the motor pulley that is on the old motor. Undo the set screw to remove the pulley. Place the motor pulley on the new motor (set screw AWAY from the motor block). Hold the pulley so it is even with the TOP of the post. Tighten the set screw. There will be a gap between the pulley and the block.   
  10. Mount the motor loosely using only the top two screws. The black spacer should be positioned hook-side down. Make sure the short belt is on both pulleys.
  11. Secure the cord behind the hook and start the bottom two screws. The motor should be able to move up and down.
  12. Press down on the motor block to add tension to the short belt. While doing so, tighten the four screws that hold the motor. 
  13. Manually move the print head and watch the short belt. If the belt moves smoothly, the motor is positioned correctly. If the short belt is loose or wobbly, loosen the motor and try again.
  14. Snap the ferrite core around the motor wire.
  15. Replace the cable cover.

Y-Motor

  1. Remove the corner cable cover over the y-motor. The screws are located one on the left panel and one on the back panel. Remove the cover while the bed is down to avoid damage.
  2. Raise the bed and lay the printer on its back. This will not damage the standard feeder. To avoid panel damage, you may want to first lay down a clean piece of cardboard or a towel. Remove the two screws that hold the electronics cover. You will need to hold the corresponding lock nuts with either pliers or a nut driver.
  3. Unplug the wire for the motor in port "Y". The motor wires are on the right side of the board.
  4. Pull the old motor wire up into the printer. Gently set the new motor in the printer and bring the cord down through the bottom panel. Maneuver the cord across the outside of the electronics board and plug it in.
  5. Replace the electronics cover. Position the black ferrite core next to the electronics board. 
  6. Make sure the flat cable and red/black LED cord are in the cut out in the top left of the cover. Screw the cover in place.
  7. Set your printer upright. Remove the four screws securing the x-motor. Hold the motor in your hand while working to avoid dropping it in the printer. Take the motor completely out of the machine.
  8. You will need the motor pulley that is on the old motor. Undo the set screw to remove the pulley. Place the motor pulley on the new motor (set screw AWAY from the motor block). Hold the pulley so it is even with the TOP of the post. Tighten the set screw.
  9. Mount the motor loosely using only the top two screws. The black spacer should be positioned hook-side down. Make sure the short belt is on both pulleys.
  10. Secure the cord behind the hook and start the bottom two screws. The motor should be able to move up and down.
  11. Press down on the motor block to add tension to the short belt. While doing so, tighten the four screws that hold the motor.
  12. Manually move the print head and watch the short belt. If the belt moves smoothly, the motor is positioned correctly. If the short belt is loose or wobbly, loosen the motor and try again.
  13. Replace the cable cover.

 

 

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