I've used EDM before, it works wonderfully but you need to find someone
that really knows how to do it. It used to be that the best place to find
the people was by talking to the maintenance foreman at a big printing
plant. Their plate clamps use hardened bolts that screw into an aluminum
drum and they break them often. Those kind of presses are a little on the
rare side now, so that might not work.
If you have a plasma torch you can zap right through the middle of a bolt
if the backside of the hole is open. Practice first though. I'm a little
scared of mine, though it sure made my cutting torch obsolete. If you do
body work you've got to have one of these. Not very expensive either.
-----Original Message-----
From: Randall Young [mailto:ryoung@navcomtech.com]
Sent: Wednesday, October 08, 2003 11:17 AM
To: FOT@autox.team.net
Subject: RE: flywheel bolts
> 1. There is a machine called a "tap disintegrator" that uses an
> electrical discharge through a consumable electrode to destroy a hard
> part in a hole.
> Usually a stationary machine, but there are a few portable ones on the
> market. Disintegrating a tap, or in this case a broken bolt, does not
> damage the threads in the part. If you can find a shop that has a
> portable
> rig, or if you want to disassemble the engine and take the crank in,
this
> is one way.
FWIW, there are also plans running around to build one of these on your
own. It's called Electrical Discharge Machining, or EDM for short, and
I've seen
several articles published in Home Shop Machinist. I believe you can
still
buy the back issues with the various articles, and they also sell reprints
of one of the more detailed articles. http://www.homeshopmachinist.net/
One of the articles talked about using the unit to machine out a broken
and corroded steel stud in an aluminum engine block, made it sound easy
(although slow).
Randall
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