Paul Mathews wrote:

You can buy or make a little tool that extends 3 'fingers' into the
tap grooves and will (sometimes) allow you to back out the tap
fragment. It sometimes helps a lot to first pour a little acid down
in the hole to loosen things up. Lubricants serve the same function,
but don't work nearly as well.
If the hole is a through-hole, here's another method that nearly
always works: simply press the fragment out. This will tear some
grooves in the wall of the hole, but there is quite often sufficient
metal remaining for adequate threads, and the results won't leave any
trace of your folly to hurt your pride.
Paul Mathews

I have never had much luck with tap extractors smaller than #10 in
aluminum. Aluminum is to gummy and I end up breaking off one of the
fingers. This is relatively painless and leaves clean thread. Besides,
it appeals to my scientific curiosity. :-)


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com