I broke a tap today. There was not enough protruding for me to get a
grip
and twist it out. I thought I would anneal the tap in situ and drill it
out. So I heated it red hot with my TIG torch and let it air cool.

When I tried to drill, I found it was still way hard and I abandoned the
idea of drilling out the broken tap. I had the flexability to drill and
tap
beside the original hole so there was really no great loss. But, what if
I
really needed that particular spot?

Would I have had better luck drilling had I cooled the part more slowly
(e.g., buried the part in a bucket of ash)?

Is my thinking nuts or is this a way to get at an offending broken tap?

TIA,
David Todtman



You are almost there with your tig. Sharpen the tungsten to a perfect point,
then start with low heat and carefully liquify the tap holding the electrode
in the center of the tap. I keep increasing amperage slowly until almost the
entire tap is melted. Then with stainless rod, add filler slowly until you
have a ball built up on the tap. While it is still hot grab the ball with
vise grips and gently work in both directions to loosen, then screw it out.
This works about 50% of the time or more. I have been brought expensive
parts to remove taps with an edm and almost always try this first. Some
customers will come back the next day for their "edm" job, when in reality I
have the tap out before they are out of the parking lot! And of course I
don't charge them for the much more expensive edming.(grin).
Dixon