Replacing Cracked Sliding Blocks
The following guide is on how to replace the sliding blocks on your Ultimaker 2/2+ and Ultimaker 3 printers (it was created with the help from Ultimaker's Taiwan distributor: 3DMart Taiwan)
1. Release the print head shaft from the existing cracked/ broken sliding block.
Cracked sliding block
2. Use a flat head screw driver to release the clips on the bottom and the top of the sliding block to open the block.
Remove sliding block
3. Once open, you can see the spring and sintered bushing (the bronze cylinder). Be careful that the spring doesn't fall off from the belt. Pay attention to how the existing belt and spring sit within the sliding block and avoid moving the spring.
Belt spring and sintered bushing
4. Replace with the new sliding block, ensuring the spring, belt and sintered bushing sit perfectly in the new block.
Fitting the new block back together
5. Make sure the spring and belt are in the correct position after the buckle, then snap the two halves into place.
Snapping the block back together
6) Once replaced, fix the print head shaft back into the groove ensuring that the sliding block is always perpendicular to the rods. Make sure that the shaft is firmly secure into place. Usually you can hear a click sound when you push the shaft back into the groove.
Reassembling the print head shaft into the sliding block
7) Refer to the following diagram to ensure that the shafts are installed properly. The X shaft should extend out from the sliding block on the left of the printer to ensure that the shaft activates the Y limit switch. The Y shaft should be flush with the rear sliding block so it doesn't rub or collide against the Z rods/ screw.
Correct positions of the X and Y shafts
8) The shafts may have misaligned if the spring in the sliding block comes loose while you were replacing the new sliding block. Ensure that the shafts are straight by aligning the print head shaft with the axle alignment tools. Each of the shaft should fit into the same notch of the alignment tools on both sides of the print head.
Using the axle alignment tools
9) If the shafts are not aligned you may loosen the grub screw of the corresponding pulley with the supplied hex screwdriver, and gently nudge the shaft into place until perfectly aligned. Retighten the grub screw once the shaft is aligned properly, check the alignment again after the screw is tightened. Move the print head around to make sure that it moves freely without requiring excessive force.
Loosening and tightening the pulley for adjustment