Replacing x-axis 6mm idlers w/9mm ones

Anybody else struggling to replace the 6mm idlers with 9mm ones for the 9mm belt upgrade using the “instructions” Inventables provides, which don’t say anything about having to disassembling the gantry? Well for those who are still scratching their heads, I have a hot tip.

You’re gonna laugh, but it worked.

It’s next to impossible to tighten the lock nut on the 9mm idlers. As the nut is tightened, it recedes into the idler. So a wrench can’t be used. (You might think, oh, just turn the idler around the other way, but that results in the idler being out of alignment with the motor gear.) The space inside the makerslide isn’t wide enough to get a socket wrench in either. Here’s the only solution I was able to get to work…

I sacrificed a 8mm socket by welding a 1/4X6" bolt to it. Worked like a charm.


Necessity is the mother of invention…! I’m not laughing, I’m loving it!


Brandon Parker