"Jerry Built" ] wrote in message
news:J2EIN5AGGJMIB1MFCCCKDZKAGDAGNXNVJVDSAGML@zipl ip.com...
The Natural Philosopher wrote:
Abd of course the stud extractor - a reverse threaded self tap
screw with a socket top...it screws in to any hole anti-clockwise
and jams there.

Sometimes ;-)

Sometimes, it expands what it was driven into and causes it to get even more
jammed into the threaded hole :-((((


Useful for extracting non-siezed broken threaded components -
otherwise useful for jamming undrillable fragments of hardened
steel in holes drilled in siezed broken threaded components.

The solution to this un-drillable problem is to find the drill to drill out
the extractor. I would suggest you buy a solid tungsten carbide drill, as
used by the engineering industry (usually for drilling carbon fibre) to
drill out the extractor. And yes, I have done it many years ago, several
times.

There is nothing un-drillable.

Dave