I remember seeing ads of companies who sell lathe chucks who will thread your chuck to match your lathe. Can’t find these companies now. I have an old lathe with a 2 1/8 x 8 tpi spindle. None commercially available or on the used market apparently. And many have told me I can bore and thread the chuck myself. My chuck is 0.006 out of round so if I bore my new one on it it will be off center too. Anybody know a source?