Using Heat on Stuck Things, it works based on Physics

[SuffolkD at aol.com]

Lister(s):
I'm no expert in the properties of metals........but Dan's post referenced 
made sense to me.
Here's why:  The O2 sensor (Dan's post) is a threaded hole in a Round pipe.

If one heats the round pipe with a torch, the metal (for this example) will 
expand from the bottom up if the flame is pointed there:  the bottom of the 
pipe when heated will expand...........in this example I can see the top of the 
pipe (where the threads are) being compressed from the heat - from the bottom 
of the pipe - expanding.

If one tries to heat the top of the pipe where the threads are: it would be 
difficult to keep the heat from the O2 sensor which would expand from the heat 
in this case making the sensor expand in the threads still causing a "bind."

Which would be the better option?
If I could keep heat from the sensor and use a pin point flame, I'd go at the 
O2 threads in the "top" of the downpipe.

So in review I think WHERE the flame is pointed will be the most important if 
heat will help in taking things apart.
Gentlemen?
-Scott by BOSTON

> From: "Larry C. Leung" <l.leung at juno.com>
> Subject: Re: quattro Digest, Vol 2, Issue 162 Using Heat on Stuck
> Things,    it works based on Physics
> To: quattro at audifans.com
> Message-ID: <20031221.153314.-407579.1.l.leung at juno.com>
> Content-Type: text/plain; charset=us-ascii  
> Dan, et al,
> 
> Although it seems like the hole should get smaller, quite the 
> opposite is true (unless you do something foolish like heat
> the stud/bolt instead of the surrounding material or nut)....
> 
> BTW, I had a lot of difficulty with this topic until I thought it out.
> 
> If you think of the material around the hole as being made of
> links, each link will expand, correct?
> 
> If so, then the circumference of the hole will get larger, right?
> 
> Thus, the holes diameter will actually increase rather than 
> decrease. It seems counter-intuitive until you think it out carefully. 
> Thanks to Larry Gonick in his book, Thinking Physics.
> The heat also helps break the bonds of corrosion, but that's another
> topic.
> Happy Holidays, all!
> 
> LL - NY, a.k.a. the Physics Teacher
> 
> > From: Dan Cordon <