Over on Western Thunder a fellow member posted photos of a hand crank that he had made for his lathe and I said that it might make a good side project at some point.

Talking of side projects. I have mentioned a few times that I am using a Spin Indexer to index the gear blanks for cutting.

Most comercial Spin Indexers are made in China and having seen quite a number of videos on the use of, and improvement of them one thing that pretty much everyone comments on is the locking screw which locks the barrel both while indexing and fitting and tightening items in the collet holder. As supplied they come with and aluminum screw which has a nice knurled head but that’s the only good thing that you can say about it.

The fit in the internal thread is so sloppy that I wouldn’t be surprised if there wasn’t getting on for a millimetre of play in the thread. Now most of the videos that I have watched have been Americans and the other thing that they found really frustrating was that they couldn’t work out what thread it was. That’s because it’s an metric M12 x 1.75 thread.

I do have a tap and die for M12 x 1.75 but by good fortune I was recently given a bag of big bolts to use as raw materials and amongst them was a number of M12 coach bolts. I tried screwing one of them into the hole of the Spin indexer and the fit was perfect.

I cut of the head of the coach bolt and then cut a length of the threaded section and included short length of the plain shank, which I turned down to make it round as it was slightly oval to start with. Then I drilled all the way through 5mm because the aluminium version has a hole through it. I opened out the threaded end to 8mm and turned a brass top hat bush to fit inside it and secured it with Loctite.

Next I used a boring bar to open out the hole in the knurled part of the aluminium screw until it fitted the turned down section of the replacement threaded section. Then I parted it off and Loctited that to recreate the screw.

Now I have a screw that will tighten down properly with no slop in the threads and the brass end will stop the barrel of the Spin Indexer from getting chewed up by the steel screw thread.