[TheForge] stubborn rivets

[jerry Frost]

I'm taking your comments as a "for conversations sake" bit of funnin. I've
been waiting but nobody's pointed out the obvious flaws.

 First flaw. Einstein would never take one of his little thought experiment
voyages regarding a question and deliberately leave out a salient point. The
hole.

What happens to the hole IS the question. 

Then there is your rather cavalier altering of the method in question.

How are you measuring diameter change in the scribed circle?

In answer the effect on a HOLE is the sole purpose of this technique. First,
you can't heat the hole, it isn't there and no the rivet doesn't count in
the effect to the hole. 

Heating the plate will cause it to expand. Because the subject is a spring
and the purpose of the process is to remove the rivet without having to
remove the spring ruining the heat treat of the spring is contraindicated.
So, NO it's not getting heated even near red heat, stopping at or under
400f. will do the job without damaging the heat treat.

Now what happens when the steel is heated and expands. It's only being
heated in the area we need effected say a circle not much more than half an
inch large in radius than the hole, call it 1.5" dia. for your thought
experiment. Simple physics tells us force ALWAYS takes the EASIEST path. The
3/4" of 1/2" thick steel surrounding the heated zone is elastic but not
easily malleable at this temperature. However the hole offers silly minimal
resistance to deformation and WILL shrink a few thousandths and upset a
couple few ten thousandths.

If on the other hand you do this without the hole it will as has been
described upset in the center or warp. Much of the effects of heat expansion
will draw themselves back out and you'll need micrometric measuring tools to
measure it.

Got a better subject for discussion Bruce? This one is too easy unless a
person didn't take high school metal shop. I will admit I'd forgotten that
bit of desk work in the shop till I needed to remove a rusted in rivet a
couple decades later. Wish I had those text books now. Most of it was pretty
darned low tech compared to now but it was full of hand tool how to.

Frosty
-----Original Message-----
From: TheForge [mailto:theforge-bounces at mailman.qth.net] On Behalf Of Bruce
.
Sent: Wednesday, August 10, 2016 3:54 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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