Subject: Re: ahhhh it's good to be home

From: [email-masked] (Morgan Hall)
Date: Wed, 23 Dec 1992 16:04:46 GMT

In article <ijeff.725071811@cunews> [email-masked] (Ian Jefferson) writes:
>Here is a question for someone that has puzzled me for years:
>
>When seperating two metal parts, usually steel and steel, it has been
>common pratice to apply heat to the parts to free them.  The effect
>is especially noticable in steel on steel parts.  Why does this help?
>I first though that expansion of the heated part might be the reason but
>in the case of a bolt in a caseing it seems to be more effective to heat
>the bolt rather than the caseing. 
>
>Ideas?

My guess is that several things are happening.  In some cases oil & grunge
have formed a mechanical jamb fit between the parts.  Heat breaks down the
compound that is blocking the parts and lets them slide free.
In some cases there may be microscopic bonds between the metal of the two
parts that the differential expansion breaks.
I think though, in most cases when we're talking about steel, we're dealing
with red rust.  Red rust (ferric or ferrous oxide, I can't remember which
is which) roughens surfaces, occupies more space than the original iron,
and tends to grow together into a mass.  Heating the red oxide can change
it into the black form and the change breaks down the structure of the
red mass.  

Morgan

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From: [email-masked] (Phil OKunewick)
Date: 23 Dec 92 19:33:42 GMT

[email-masked] (Ian Jefferson) writes:
> [ nuts and bolts ]

   Somebody else posted the reasons why this might work.  Now here's a
no-heat alternative:

   Pound on one of the stuck parts, driving it directly into the
other.  If its a stuck lug nut, put a wrench socket onto an extension
that just fits over the stud, so as to pound the nut into the wheel.
Don't be afraid to convince the mess that you mean business - hit it
HARD!  (Any good socket has an unconditional guarantee, but can take
this abuse anyway.)

   This will break rust bonds and stretch/compress everything just a
little bit.  In many cases the stuck part will then spin right off.
I've used this successfully to remove lug nuts, lug bolts, exhaust
manifold studs, you name it.  (A friend showed me this after popping a
couple sockets and breaking a breaker bar on some Audi lug bolts.)

   Use discretion of course.  The object is to disassemble things, not
destroy them.

   Another alternative is to apply drops of muriatic acid right onto
the rusted joint.  It will take several applications over many hours
or days to eat all the way through the joint.  This will also remove
any protective coating the parts have, which will cause them to rust
badly afterwards.

   The last choice is to destroy one of the parts, using an electric
drill, cold chisels, and/or a nut cracker.  If you're good with a
cutting torch that might work too, as the bolt can stay cool enough
that only the nut gets burned.