We’d been having some problems with our 3D printer, where at seemingly random moments, it would miss a lot of steps (up to 5mm!) on the X-axis. I suspected that the belt was too loose, which was the case, but when I tried to tighten it, disaster struck:
In spite of being on a bearing, the idler wheel had pulled on the axle (just an m3 bolt) hard enough for it to eat all the way through the plastic! Suddenly it was clear why the belt kept loosening. Since it is very difficult to print a replacement part with a broken printer, we needed to improvise. This was one of those ‘What Would McGyver Do?”-moments.
Luckily, the solution came pretty quickly in the form of an old aluminium CPU cooler that we had lying around (we had already used the fan to make the bed cooling rig). We cut two ribs to size with the Dremel, drilled a few holes in the right places and bolted them to the broken X-idler holder:
It works perfectly! Because of the metal plates, we can tighten the nut on the idler axis much more without squeezing the plastic part so much that the wheel binds. The wheel turns now without moving the axle. It doesn’t seem likely that the idler will eat through the metal anytime soon, but if it does, we have several more ribs on that cooling block that we can use.
So, as a temporary fix, this is great. But to be honest, we think we discovered a design flaw in this part: it shouldn’t have been able to fail in this way. Some redesign is needed, we’ll have to think about this. Stay tuned…