M5 nut holder for 10 series t-slot aluminum extrusion

thingiverse

I designed these for use with 10 series aluminum extrusions that are 1" x 1" square. Key differences over others like them include a nut that's twisted to grab more metal when tightened, and corners that are rounded for easier printing. Long version: As most people know, t-nuts can be expensive - $9 US for 25, plus $15 shipping, which is outrageous. So I used M5 nuts and bolts instead. I probably should have tried M6, but I couldn't find any at the hardware store, and didn't want to buy 200 of something that I'd need to grind the edges off. All I could get at the hardware stores were 1/4" (which needed grinding), M8 (too big) and #8 screws (too small). So I went with something that would grab well, but didn't need to be ground - though they're too small to touch the sides, so they'd spin around in the channel. I printed some holders for the nuts, since there were already several designs out there, but all of them had the flats of the nut parallel to the flats of the channel, and didn't overlap much. This made me worry about over-tightening the screws and pulling the channel out, so I designed some that turn the nut so it grabs as much of the channel as possible. I also rounded the edges for several reasons: 1. Printers move faster along curves than they do corners. 2. When printers do corners, they can leave extra plastic behind, since they pause at the corners (at least on my printer). 3. When printing without fans (I was using ABS, since I had lots of it), corners that angle up can start to bulge out and need to be cut off. 4. Using less plastic made them print faster. Update 8/27/2015: I needed some holders with the nut closer to the edge to get in close to the corner of a printer I'm making, so I shortened one side of the holder and included it as well - it's also in the SketchUp file.