[Healeys] spark eroding experience

[Rich Chrysler]

I am very proud to be able to relate some family history to exactly this
technology.
During WW2, my great uncle Victor Harding (my grandmother's kid brother) had
a machine shop in Royal Oak Michigan and was working closely with Packard
Engines who were having a high incidence of broken taps in the Rolls Royce
Merlin engine blocks they were producing under license from RR. These were
the Packard Merlin 225 engines being used in so many of the famous planes of
WW2. 
Anyway, Uncle Vic developed and perfected this technology so they could
remove hardened broken taps from these aircraft engine blocks. They were so
successful at this new technology, they were able to save these blocks from
being scrapped, and he was able to patent the design. He travelled for a
number of years after the war presenting lectures on the design and retired
to Sarasota Florida, having done "alright".

Rich Chrysler


-----Original Message-----
From: healeys-bounces at autox.team.net [mailto:healeys-bounces at autox.team.net]
On Behalf Of Bert Van Brande
Sent: 2011-07-08 8:56
To: List Healey
Subject: [Healeys] spark eroding experience

Not related to the plugs.

I rented a small trailer and brought the 100 4 cyl
engine to a shop in the "valley" here in SoCal to remove a broken generator
stud from the block.  These holes are drilled right into the water jacket so
these studs frequently rust solidly in place.   The stud was already broken
when I got the car/engine.  In an attempt to remove it I broke an EZ-out.
So
now there was a hardened steel bit in there as well.  Ouch.

I had another
broken bolt in the exhaust manifold.  I didn't even try, learned my lesson.
Both items were fixed in 45 minutes using spark eroding or edm.  A suitable
electrode is used and an electric discharge or spark disintegrates the
metal.
Very cool!  Here's a demo video on youtube:
http://www.youtube.com/watch?v=JRxljmABXL4&feature=related

This technology
usually can remove studs, bolts, broken taps without damaging the threads.
The thread was cleaned with a 5/16 BSF tap but there are a couple vertical
nicks on the threads in my case.  The nicks maybe not too bad to require the
use of an insert or helicoil.  I'll make sure to use thread sealant.   I
have
Hylomar thread sealant (not the advanced formulation which I have as well)
but I feel more for a Loctite or Permatex style sealant.  I love to hear if
anyone has good experience with these or other sealants.  

Overall I am happy
with the progress as this was holding me up.  

Bert
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