On Sun, 16 May 2004 01:47:33 GMT, "John Sullivan"
wrote:

I've removed some that small by "drilling", using a worn old carbide endmill
(3/32 should do for a #5) in my milling machine. Setup over the center of
the hole and raise the knee slowly up onto the endmill. By doing it gently,
you should be able to core the tap, leaving it as bits to be picked out of
the hole. It takes some patience to get through it, but it can be done.

Good luck.
John Sullivan
http://jamlab.home.att.net

If you can score a lefthanded carbide drill bit, it tends to help as
does use of a carbide lefthanded endmill.

Often times it will back out the tap after a certain point.

Gunner



"Wally Blackburn" wrote in message
. com...
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


That rifle hanging on the wall of the working-class flat or labourer's
cottage is the symbol of democracy. It is our job to see that it stays
there.
- George Orwell