This design is based on the Dual Z axis upgrade by Caster which can be found here https://www.thingiverse.com/thing:2569379. Thanks a lot for this awesome design! The reason why I made my own is that the needed parts were not available on RepRapWorld. I managed to use even less parts than the original design and you can keep your original 500mm lead screw because the belt is placed below the top beam.
The frame is much stiffer and I needed this for my project of turning this printer into a CNC machine which I am still working on.
Please consider buying me a coffee if you liked it or helped you :) http://ko-fi.com/properprinting/
Because the parts need to be a bit strong I recommend printing it with PETG, ABS or Nylon.
Yes, I should have made an instruction video, but it is not too complex to mount this together ;)
- First remove the top block of the existing leadscrew, place the pulley and tighten it lightly. Its orientation can be seen in the first picture.
- Place the belt around the leadscrew, put the block back, place the pulley as high as possible (don't force it) and tighten it.
- Tap four m4 threads in the four holes of the leadscrew nut if you want to use m4 bolts to mount the leadscrew. Otherwise use the m3 bolts, nuts and washers to mount this to the Z-bracket.
- Place the Z-bracket with the existing locknuts with the two m5 washers to the two roller guides.
- Loosen or remove the third roller guide. This is not needed anymore and causes only extra friction. I have just loosened it.
- Screw in the leadscrew until the top is at the same height as the top of the printer.
- Place the second pulley at the approximate correct height and fasten it lightly that it stays in place.
- Press the bearing in the bottom bearing holder and place this on the bottom of the leadscrew and make sure that the leadscrew goes all the way to the end.
- Mount the bottom bearing holder to the frame and make sure that the top of the leadscrew is still aligned with the top of the printer.
- Press the other two bearings in the top bearing holder, place this on the top of the leadscrew and place it on the frame loosely.
- Place the belt on both pulleys and loosen the right pulley.
- Tighten the belt by pressing the holder to the right and tighten the screws to the frame.
- Measure the distances between the horizontal gantry and the bottom frame on both sides.
- Turn the new leadscrew manually until both distances are the same.
- Tighten the right pully.
- You can move the z-axis by moving the belt from left to right. This should go smooth after you have lubricated the leadscrew. Right moment to lubricate the other axes as well ;)
1× 500mm leadscrew TR8X8 (make sure you don't buy the 2mm/revolution)
1× Leadscrew nut TR8X8
3× Ball bearing (8mm inner diameter / 22mm outer diameter / 7mm thickness)
1× 848mm closed timing belt
2× GT2 pulley (32 teeth / 6 mm belt / 8 mm ID)
4× m4×16mm or m5×16mm hexagon bolt
4× m4/m5 washer
2× m5 washer
4× m4/m5 slide nut
4× m4×10mm hexagon bolt if you want to tap m4 threads in the leadscrew nut. Otherwise you need 4 m3×10mm bolts, m4 nuts and washers.
Because the belt is placed under the top bar it comes with a little drawback that the maximum build volume is reduced a bit. I personally did not mind, but you should be aware of this.
Feel free to comment if I have forgotten anything or something is not clear :)