Graham,
Whether or not to use heat is directly related to the application.
For example:
Suppose you need to replace exhaust manifold studs. This is an area of
low precision, (it is an iron casting), and assumes no role what-so-ever
in the structural integrity of your car. Heat the ear of the manifold
cherry red and remove the stud, no harm done!
Never, ever, heat a bearing unless you plan on throwing it away!
My can of liquid wrench says to keep away from heat, sparks, or an open
flame. Whether or not a little heat will aid in the performance of this
product...I don't know!
Unless you have a specific reason for rapidly cooling the part, allow it
to air cool. Rapid cooling is usually detrimental. A bucket of ice water
would not help! Take the time to wait for the part to cool naturally, as
with the manifold example above.
Tool Steels come in a number of types.
The common ones are "O" series for oil hardening, and "A" series for air
hardening; Although there are many, many, others. The typical industrial
method of heat treating is highly controlled.
O-1 for instance is heated cherry red and then quenched in oil. You can
make tools at home using O-1 and heating with a propane torch. When O-1
is quenched it will be extremely hard and brittle. It needs to be "drawn
back" to an appropriate combination of hardness and toughness. For home
use, polish the part, (it will have a scale residue from the oil), and
reheat with the propane torch until the metal takes on a light straw
color. If it turns blue, you went too far. O-1 is cheap, and works great
for making little odds and ends that need to last. Cutters, punches,
drill bushings...etc.
Hope this helps!
Best regards,
Jim Swarthout
-----Original Message-----
From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net] On
Behalf Of Vink, Graham
Sent: Wednesday, April 09, 2003 11:34 AM
To: 6pack
Subject: Speaking of heat
Since we're on the subject, what is the best way to use heat to free a
stubborn nut or bolt?
Are you supposed to heat the offending part, or its surroundings? I can
see
how heating a nut would expand it and perhaps help to break a bond, but
wouldn't heating a stuck bolt or stud do the opposite - make it tighter
by
expanding it?
Or is the point to assume that the heating and subsequent cooling will
help
break the corrosion bond?
Does the heat make any difference in how Liquid Wrench or PB blaster
penetrates the threads?
And how hot is too hot? I assume we're discussing use of a propane torch
-
is the goal to get the piece red hot?
Also, what about cooling? Would it make any sense to use ice to try to
cool
a part?
-Graham
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