quattro Digest, Vol 2, Issue 162 Using Heat on Stuck Things, it works based on Physics

[Larry C. Leung]

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

> Date: Sat, 20 Dec 2003 16:46:36 -0800
> From: Dan Cordon <cord4530 at uidaho.edu>
> Subject: Using heat on stuck things 
> To: Quattro List <quattro at audifans.com>
> Message-ID: <3FE4ED6C.1C73FB3 at uidaho.edu>
> Content-Type: text/plain; charset=us-ascii
> 
> First off, I often use heat to get stuck things unstuck. In 
> general,
> it's quite helpful.
> 
> Just to present a different view though, I will say the 
> effectiveness of
> it depends highly on the geometry you're dealing with. For most 
> things
> found on your car, heat generally causes it to expand. So, when you 
> have
> a nut that won't come off, a little heat will cause it to "grow" a
> little, making it possible to get it off.
>  
>However, consider this situation.....You have a large, thick plate with
>a threaded hole in the middle of it. If you are to heat the area around
>the hole, the expansion of the material will actually cause the hole to
>get smaller!
 
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