This is a little experiment to drive the Z axis of a CR-10S with belts instead of lead screws The gantry does not fall when you power down the printer.
Is it an upgrade ? it works well for me but consider this an experimentation rather than an upgrade. I share it so you can get your own opinion on how it works rather than debating on how you think it will perform. Total cost is around 40€.
My opinion so far :
- One single motor to drive
- Both sides of the gantry always stay in sync
- Very consistent Z layers
- Z hop improves layer consistency (head always moves in the same direction to reach layer elevation)
- No issue created by flexible couplers of bended lead screws
- Z axis less stiff than with lead screws (suspended on belts)
- Significant backlash on Z (more than with leadscrews) which makes bed autolevelling less efficient
- Not suited if you print functional parts and need accurate z dimensions
- Long term reliability unknown
Will I keep it ? Currently yes because I'm getting better surface finish than with lead screws and I have other printers that can print functional parts accurately.
What is needed :
- Geared stepper motor (https://www.aliexpress.com/item/32526832642.html)
- 1x 20 teeth 8 mm bore GT2 pulley
- 4x 20 teeth 5mm bore idler pulleys
- 4x 20 teeth equivalent toothless idler pulleys
- 6x M5x20 cap head screws
- 10x M5x10 button head screws
- 10x M5 T nuts
- About 3.2 m of GT2 belt
- 2x M3x20 cap head screws
- 4x M3x10 cap head screws
- 2x M3x40 cap head screws
- 4x M3x8 flat head screws (to attach the geared motor to its support)
- 8x M3 hex nuts
All parts are in suggested orientation for printing. Bottom idlers require supports in that orientation.
All idler pulleys are attached using M5x20 screws that you directly screw in the plastic parts. For the motor holder, you will need to put 1 printed washer between the idler pulley and the printed part (2 printed washers required in total)
All parts are attached to printer frame using M5x10 button head screws and T nuts (regular M5x10 cap head screws should work too)
Belt tensioner works in the same way as Prusa's one (refer to https://manual.prusa3d.com/Guide/2.+Y-axis+assembly/1046, step 35). You need to print 2, one for the top, one for the bottom. Nuts are only needed for the bottom one.
Clamp the belt on the extruder motor plate side by tightening the screws after you have aligned everything and tightened the belt. Use longer screws to put the captive nuts in their housing.
A few tips
- As you can see on pictures, not tested with the stock extruder / print head
- You will need grind a bit with a file the extruder motor plate to make room for the belt
- After removing the lead screws, check that your gantry moves very smoothly on all Z height and that it doesn't wobble along X direction
- On the right side, make sure the belt does not rub against the sides of what used to be the lead screw hole
- Put minimum tension on the belt. Too much tension will make the imperfections in pulleys popup and increase backlash
- In my case, new steps/mm for Z : 419 (vs. 400 with leadscrews)