Low Profile Adjustable Y Belt Holder

thingiverse

I wanted to create an adjustable y belt tensioner for my new Prusa MK3 Bear build, but none of the existing designs met my expectations. The first option that came close was Thingiverse's 2995737, which levels force vectors and has good clearance, but finding a high-quality 16T idler is challenging - if you know where to look! I'm not sure if moving to a 16T idler is desirable, as it increases the lever arm, so I might create a 20T idler version instead. My next choice was Thingiverse's 3069061, which inspired my design. However, I didn't like that the belt length had to be cut to fit and accessing the adjustment screw was difficult. The main reason against this option is that it lacks sufficient clearance for the belt. Thingiverse's 2904281 is another decent idea, but its rotating nut isn't ideal, and it's quite bulky. For now, it's my backup plan if my design doesn't prove satisfactory in the long run. I'm not completely happy with my design, but it addresses some issues I've seen. It retains a 20T idler, has a small form factor like the original Prusa design, and allows for belt adjustment without cutting the length. It also provides sufficient clearance and makes the adjustment screw more accessible by placing it on the other side where there's more space between the belts. I still see some potential improvements, such as interlocking the screw-on plate with the lower part to improve stability. However, I'll try this version first before making it more complex. There are two versions: one for perfectly dialed-in printers and another that requires a little super glue for a perfect top. It's also a good idea to apply a small amount of glue to the square nut to prevent it from coming loose when not under tension. The hex nut has a one-layer bridge that needs to be drilled through, allowing it to print without support - re-drilling the holes as a post-processing step is recommended. Materials needed: * 1x M3 hex nut * 1x M3 12mm countersink screw * 1x M3 square nut * 1x M3 35-45mm screw (depending on desired adjustment range, max 45mm or it hits the motor) * Super glue * 3mm drill Note: I use the Prusa code as a starting point and follow the GPL.