On Sat, 15 May 2004 23:43:37 GMT, tomcas
wrote:

Wally Blackburn wrote:
Well, I've broken off my second 5-40 tap in cast iron (model steam
engine). One I got out with an extractor - the second one I've
buggered up so much my only hope is to drill it out.

I've read a number of posts about drilling them out with carbide bits.
When I look in KBC, Wholesale Tool, etc., I see solid carbide jobber
bits for 10 bucks or so in size 39. Will one of these do it? Because
I also see a "square die" carbide bit that specifically mentions
drilling out taps - but it's $35...

If I need the $35 bit, so be it. But, if a regular carbide jobber bit
will do it, I would obviously rather go that way.

TIA,
Wally
I don't think it is possible to drill out a tap. We always EDM them out.

EDM is the best way to do this, but a "christmas tree" carbide burr in
a high-speed (at least 50K RPM) air tool will do the job.