A redesign of my previous clone of the Park Tools DP-2 dummy pedal. The previous design used the same 5/16" thread for the shaft as the Park design, and that was a bad call. It's far too thin and far too weak.
This is a design based on the other but optimized for FDM printers and their limitations. Now there is no 5/16" thread - it's all 9/16" with the same short threaded bit so you don't have to screw it all the way into the pedal. The threaded insert is small and should be printed at 100% infill for maximum strength, but everything else can be a much lower infill.
- Assemble the threaded insert into the shaft - it uses a Torx T30 on both ends, but you might be able to thread it in by hand.
- Put the shaft with the threaded insert through the handle.
- Screw on the grip until it bottoms out.
- Confirm everything turns nicely
I made the T30 in the threaded insert a thru-hole as it is still possible for the insert to break if you're a bit too rough with things - and in that case having the T30 in there makes it easier to remove the remnant to install a new threaded insert. I keep a couple of the threaded inserts on hand as those are what will fail, and the rest of the parts should be just fine. (photos show an early prototype with provision for a slot screwdriver - I can post that if it works better for folks)
Also included is an STL for a pegboard holder which keep the dummy pedal handy.