[TheForge] stubborn rivets

[Dave Smucker]

Some may have missed what happens when we heat a "small" area of a large piece of steel.  We cause the heated area to upset some.  Why? Because it can't expand the way it would like because it is held in place by the cooler (and stronger) metal around it so it upsets or gets thicker.  Now when it cools it shrinks so now it pulls on the metal around it.  We can use this to straighten a weldment by using a torch on the other side from a weld that has caused distortion.  Another use it to tighten a collar that is set but a little loose.  Just take a torch and heat a small band on each side of the collar and you will cause it to upset in these areas and then shrink, and tighten when cool.

Dave Smucker
Brasstown, NC

-----Original Message-----
From: TheForge [mailto:theforge-bounces at mailman.qth.net] On Behalf Of Bruce .
Sent: Wednesday, August 10, 2016 7:54 AM
To: Blacksmithing List Sponsored by ABANA
Subject: Re: [TheForge] stubborn rivets

Okay, guys, it's time for one of Einstein's "thought experiments":

Take a steel plate, maybe 1/2" x 3"x3".  SCRIBE a 1/2" circle in the center of the flat so the circle will survive a little abuse.  Heat the plate to below red.  Quickly measure the diameter of the circle.

Does anyone think that the circle will have got smaller?  If so, please justify your conclusion (or share whatever you've been smoking).

So, why should it be different if that scribed circle were a drilled hole?

Now, I defer to greater experience whether heating is a good means for removing a rivet.  I find that truly experienced workers usually know HOW to do something, but often can't explain WHY it works.  "How" is more important practically.

Bruce
NJ

On Tue, Aug 9, 2016 at 9:21 PM, jerry Frost <akfrosty at mtaonline.net> wrote:

> Bingo Mike. No, heating the spring will NOT expand the hole making the 
> rivet drop out. As Mike says the hole will shrink, this only works on 
> rings say a nut on a bolt type situation. In the center of plate like 
> a leaf spring it's a no go.
> removing them.
>
>
>
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