I have been gathering ideas for building my own ~24"x36" CNC Router. I really like the belt on belt design for linear motion. I have an idea for a variation on the belt on belt that I haven't seen before and I would like input as to positives or negatives.

It seems the existing belt on belt designs engage the stationary belt with 2 sections of belt.(See right side of pic below) This then requires adjustment to tension the belt while ensuring proper tooth spacing between the different sections of belt. Lots of layouts could have this facing the inside of router and visibility of the 2 belt adjustments maybe hampered. 2 reasons I could see for this is backlash prevention when there is space where the belts engage or it uses a more readily available single side belt.

My idea is to use a double sided belt (See the middle pic on the left side). This would reduce the adjustment to just belt tension as tooth spacing would be fixed. It also seems to be a simpler design with fewer moving parts. From a backlash perspective, I think finding a belt on belt profiles that press into each other instead of having a bit of gap between the teeth would reduce backlash significantly. So I did a comparison of various 5mm belt profiles meshing shown below. It looks like the T5 on AT5 belt has no space between the teeth while maintaining good engagement.

Let me know your thoughts.

Thank you,

Jerry