Sorry for a bunch of posts at once. I worked all day long (almost) and
gave 1500 lbs of old junk to a scrapper.

Never had this problem before and I REALLY do not want to screw up.

The head of the Bridgeport CNC mill is attached to the turret with
four socket head cap screws, probably 1/2". They have a 3/8" hex hole.

All my attempts to unscrew them failed. I used a nice Unbrako L shaped
key.

Cannot do it without leverage.

With leverage (pipe) the key twists so much, that I really do not want
to push my luck.

I made a tool today from one 3/8" L shaped key: I drilled a
perpendicular hole close to the end of a pipe, and welded the straight
end of the key into that hole. So I can use the pipe as a lever to
turn the key without as much length to twist.

-. (L key)
pipe |
============|=

^ this end will go into the SHCS

I have no idea how will the key behave after having been welded.

I also have hex keys that are driven with a 1/2" breaker bar or an
impact. I am really afraid that it may somehow break the SHCS, which
would be terrible considering its job (holding the mill head).

Any comments?

i