John Aniano in NJ...
>Wiley,

In the bow restoration world I live in, we come across wild sizes of threads for the button screw and frog eyelet of a bow - the two in combination give the adjustment to tighten the hair. 19th century bow hardware had no standards until near the end of the century.

When all else fails, and this has happened more than once, I turn to my trusty South Bend metal lathe, turn a short piece of water-hardening steel to the proper diameter (in your case 0.290"), set the quick-change gear bow to cut a 1/16" pitch thread, and go at it. When done with the threading, use a saw sharpening file to cut two flutes into the steel bit, relieve the edges so it will cut and finally file a square shank on the opposite end. Harden and temper and use the tap!

Works for me...

John