I may need to make a thread insert for a woodturning chuck and I'd appreciate some help from experienced machinists. I have a decent thread-cutting lathe, but the job is outside my (limited) experience.
The problem is that my wood lathe has a 1" 12TPI thread and the chuck has an M40 internal thread. A range of inserts are available for the chuck, but not one for 1" 12TPI, sadly. I think I have 3 options:
- buy a blank insert that's threaded for M40 on the outside and bore/thread it 1" 12TPI. This will need removing and resetting several times to test the fit and it will be difficult to maintain the concentricity. Alternatively, I could turn a male thread as a test piece, and use an existing 1" 12TPI faceplate as a test piece for the male thread. Making a thing to make a thing.
- turn the insert from a plain bar. First, bore and thread the 1" 12TPI (keeping concentricity when returning it to the lathe after a trial fit should be easier because the bar is longer and the outside is turned smooth and concentric with the bore). Then, thread the outside M40. and use the woodturning chuck to check fit without disturbing the adapter in the lathe chuck.
- hold the woodturning chuck in the metal lathe chuck and screw the blank insert into it. The insert can be removed and replaced to test fit without affecting concentricity.
I'd appreciate any and all suggestions.