25mm Conduit Polishing Jig

thingiverse

I needed a secure hold on my 25mm conduit for sanding and polishing, which I was using in my MPCNC build (https://www.thingiverse.com/thing:790533). The conduits from Screwfix UK (https://www.screwfix.com/p/deta-class-4-conduit-tube-galvanised-25mm-x-3m/7442j) were quite rough and produced a lot of noise when the bearings rolled over them. Now, the rods are nice and smooth. I modified the original design to accommodate the M8 hex screws I had on hand and added a few extra cutouts from the expander for a uniform grip. The internal diameter of the tubes was 21mm. I used spare parts from my Prusa Mk2s for the nut and washer. Bolt holes might be slightly tight. I left a 0.4mm clearance. If your bolt doesn't fit, use an 8mm drill bit to drill it to size. **Credits:** Although I designed it from scratch, I got the idea from The_Cheat (https://www.thingiverse.com/thing:1329637), which is why I'm marking this as a remix. **TIPS:** Using the drill counter-clockwise tightens the grip (use it this way for polishing), and drilling clockwise loosens the grip. This makes it useful for insertion, removal, and polishing. **UPDATE:** I added a flange to the expander to make it easier to remove.