July 12, 2014: First trials conducted by Dan DeGagne and Ashley Webster at the VHS. We adapted the technique used in this video.
We began by cutting a groove into the bolt at the desired location. The bolt was inserted into the chuck and turned against a cutter held in the vice. The top bolt is the original from the Tantillus which needs to be replaced. The groove position was measured from the bottom of the bolt head. The bolts were not perfectly straight so the grooves are slightly eccentric, less so on the shorter bolts.
Insert Dan's pictures «
Next, we placed the bolt into the hobbing jig held in the mill's vice, and turned a 1/4“ tap against it to cut the teeth. We produced three (hopefully) usable bolts, one for an Ultimaker and two for the Tantillus.
Lessons
- You can cut too deeply very quickly
- Go slowly and let the bolt make several revolutions each time you feed it to ensure an even cut
- Shorter bolts work better because they are straighter
- Use M8 bolts if possible so they fit standard 608ZZ bearings. The 5/16 bolts were a bit loose.
- We had some concern about the 3D printed jigs but they were very strong, printed in PET at 100% infill.
- The Tantillus would benefit from having a shorter, Wades' style bolt. They are easier to cut and easy to source ready-made.