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Looking at a Jaguar

To: uunet!alliant.com!british-cars@uunet.UU.NET
Subject: Looking at a Jaguar
From: mit-eddie!sli.com!rdh@EDDIE.MIT.EDU (Robert D. Houk)
Date: Thu, 15 Mar 90 16:21:08 EST
   In reply to Ken Neff concdeerning the broken screw extractor.

   About 10 years ago I had a similar experience on a '65 TR4A.  I broke off a
   stud on the head, tried to use a product called a n "easy-out" or screw
   extractor and broke it off.  I took the head to a machine shop and 
   they told me to go and buy another head!  I had a guy come over to the house 
with a torch and try to loosen it to no avail.  A few days later on the way home
   from work I remembered a professor saying that if you want to do some 
   good grinding you needed a good impedance match.  That is your work piece
   should be as hard as your grinding tool.  I went to a hardware store and 
bought about 6 small grinding stones like the ones which fit in a Dremel tool.
   Those stoneshe dremel tool ( a high speed rotary grinder) really ate through 
the 
   screw extractor.  (I think I used most of the 6 grinding stones.) After I
   got the "easy-out" out, I drilled out the stud , tapped it and put in a 
   threaded stud.  'Worked like a charm.  The 6 grinding stones cost about
   $2 - $3 each which was less expensive than a new head! Good luck -

There is another alternative. There is a process of "electron discharge"
machining (don't remember the actual name), but it can perform miracles
in the above-like case. It is also a lot more expensive than, e.g., a
handful of dremel bits, but can remove the broken extractor 100% while
taking 0% of the head (or broken stud). By extension, it can take 100%
of the broken stud and 0% of the head. Unfortunately, it has been [way
too many] years since I remember reading about it, but maybe a good ma-
chine shop could tell you [or someone else on this net?]. It may or may
not be cheaper than a new head...did you try penetrating oil (like Li-
quid Wrench?)?

                                        -RDH




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