K40 Laser engraver/cutter idler pulley

thingiverse

Update - 20th May 2019: I've been running this fix on my K40 for almost two years now, and it's still performing better than the original part. The pulley idler on my K40's X axis had worn down significantly, causing the belt to pop off every few jobs. To avoid waiting for a replacement, I designed a quick solution to get me back up and running. I added a larger "lip" to the new idler to securely hold the belt in place. To install it, remove the bearing, screw, washer, and nut from the existing idler and install them into this new one. You might need to tap the bearing gently with a hammer to get it seated properly (and possibly the same to remove it from the old idler). I designed the new idler to be tight but not too tight, making it easy to tap in. It's probably best to print this part in nylon or another durable material, but PLA with 100% infill will work if you're just waiting for proper replacement parts to arrive.