The X gantry on the QU-BD OneUp sags noticeably downward on the right side. I didn't like any of the existing fixes for this, so here's my version.
You will need 3qty 8x22x7 bearings and a guitar tuning head to complete this project.
I had no problems doing this with 3 walls and 40% infill. You may need to rotate the STL files to print better for your printer, but keep in mind these will be under tension so print in a direction that is strong as well. You will need to print 6qty of the pulley bearing side pieces, two for each side of the bearing.
- Super glue two sides around each bearing, for 3 pulleys total.
- Attach parts. This is pretty straight forward, just go off of the STL names (and see my example shot). The Z bearing mounts will replace the existing square ones included with the OneUp, but will re-use the screws. The top pulley braces may need to be drilled out to accommodate your screws, if they are too short to reach the rods. Just drill them out so the screw head fits nicely all the way down to the MDF.
- On the bottom left pulley bracket, try to position it (and all pieces generally) in line with the Z rod so the wire travel path is straight.
- Tie some type of wire (jewelry wire is what I used, braided fishing line would probably work great too due to low stretch) on to the left Z bearing mount stud, loop it through the pulleys to your guitar tuning peg on the right Z bearing mount.
- Tighten until level. I would suggest leveling the bed height based on distance from the counter you have your printer sitting on. Then level the gantry to the bed.
This is all designed in Fusion 360.