22mm Trapezoidal Screw Adapter

thingiverse

I bought several THSL-300-8D Z-Axis threaded rod upgrades for a bunch of Prusa i3 DIY clones I assembled myself. The trapezoidal TR8 screw nuts @ 22mm wide, however, didn't fit the Prusa Z-Axis parts because they were smaller than the ones Prusa uses. I searched everywhere for the correct size TR8 nuts and came up empty-handed. Not wanting to reprint the ABS parts, I decided to build a simple adapter instead. Taking inspiration from Tom Sanladerer's "Z-Axis nut Holdah" designed for 5mm threaded rods on his Dolly i3 Clone, I modified his nut holder to fit the TR8 trapezoidal nut and added two M3 nut recesses on the bottom and two M3 bolt/cap recesses on top. To assemble it, push the nuts into the underside of the adapter, screw the adapter into the Z-Axis threaded rod slots, and secure everything with a pair of M3x6mm or 7mm cap bolts. If you can't find the correct size M3 bolts, almost any nearby size along with some M3 washers will work just fine. One small trick to get the nuts in more easily is to place an M3 bolt with a washer through the top side of the adapter, screw the nut onto the shaft, guide the nut into the recess, and tighten the bolt. As you tighten the bolt, the nut will slide smoothly into the recess.