[AT] EDM (Electrical Discharge Machining) Drilling on old tractor steel and iron.

[bradloomis at charter.net]

This looks like what Mr. S Zabelski (That's a guess) was speaking of. I haven't yet run across a situation where I've needed such a critter, tho I've broken several taps. Mostly under 1/4" in stainless. I think the stainless is harder than some taps. Most always oversize the drill holes in stainless. Nice tools to know of if I ever need and have an extra $100 for a set. 
https://www.aircraftspruce.com/catalog/topages/tapextractor.php?gclid=EAIaIQobChMI1tnukojM5QIVYhh9Ch0W7gT7EAQYBSABEgLduvD_BwE
Brad

[Gene Dotson]   We knew it as a tap burner.

[szabelski at wildblue.net] When I worked in a tool and die shop we used a tool to extract broken taps. The tool consists of a set of fingers that look like small Allen wrenches and a handle that the fingers go into. You slide the fingers down into the tap flutes and then into the handle. Then you tighten a collar on the handle and it secures the fingers in place . Then it’s just a matter to turning he handle to remove the tap. Works great as long as the tap hasn’t shattered into pieces, then you have to sit there and pick out the pieces (usually just a few pieces near the top of the hole) one at a time until you can get the tool to work.

When this wouldn’t work, the tap would be burned out. This was usually only done when the tap had broken into a bunch of little pieces that were all jammed up in the hole.

Don’t remember what the tool is actually called, but you should be able to search the internet to find it.

_______________________________________________
AT mailing list
AT at lists.antique-tractor.com
http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com