If you are using flat belts, this seems to be a quick easy way to build guides to keep them in place. Each guide is a 3D-printed standoff with a small 3D printed roller that sits around it. Works great and doesn’t require any machining other than drilling a rivet hole, as long as you have a frame member in a good location.
What is that blue roller material? We’ve had some issues with our polycarbonate tubes flexing from the polycord.
It is a 6061 aluminum tube, 1.25" OD and 0.065" wall thickness. It’s very stiff and lightweight, and it’s just the right size to allow pressing a 1.125" OD bearing into the end. It is anodized blue from the manufacturer.
You can also keep the belts tracking by taking an O-ring and electrical taping it in place to act as a crown to keep the belt where you want it.
Or just actual tape, though our testing this year has shown that flat belting like this in the bottom of a hopper with a large mass of unconstrained balls on top of it very easily derails.
Second, just a couple wraps of electrical tape directly under where you want the belt to sit works perfectly
We haven’t had issues with it, but apparently you have so I guess it depends on setup