Thanks for the amazing instruction! My build of AR3 is almost finished. However, there is a backlash problem on J2. Here is the video: https://photos.app.goo.gl/NFMZ6KbqRHfPEMBD8
The J2 spindle are 3D printed by PETG with 90% infill. The backlash makes the robot shaking quite a bit when I jog J2.
Is this amount of backlash normal? Or do you have any suggested method to fix this? Thanks a lot!