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Re: [Shop-talk] Annealing Copper bars

To: Jack Brooks <>, shop-talk <>
Subject: Re: [Shop-talk] Annealing Copper bars
From: David Scheidt <>
Date: Sun, 9 Aug 2020 09:20:34 -0500
References: <> <> <> <> <>
On Sat, Aug 8, 2020 at 5:51 PM Jack Brooks <> wrote:
> Insulation - BINGO!  Great thought Donald!
> I underestimated copper's heat transmission rate.  Using propane, I could not 
> get a 1/8 x 1 inch x 8 inch bar to get to glow with the bottom of the bar 
> clamped in a vice.  I decided to try "Insulating".
> I laid a 3 inch long copper bar (typical busbar length) across the teeth of 
> two sections of a coarse hack saw blade clamped off to the side of my vice.  
> There is almost no contact between the copper bar and these supports, only 
> across the tips of the teeth on the two halves of the hack saw blades, so 
> maybe a dozen pinheads.  With this arrangement and with a partially-dark 
> room, I could just barely see the red glow in the copper. After a quench, the 
> copper bar was soft!

That's a clever way of doing it.  A firebrick is the usual suface to
put things on while they're heated.  For a propane torch, you could
use a regular brick, or a cinderblock. They don't work with a welding
torch, because they explode.  Also, there's a surprising difference in
torch output.  A few years ago, I couldn't get a 1" copper fitting hot
enough to flow solder using the crappy propane torch I'd had for 20
years.   I bought a Bernzomatic TS-8000, at the advise of a plumber,
and it did it with out breaking a sweat.

> I now have a method.  Now I have to insure that I can clean up the contact 
> surfaces well without affecting the flatness and I can go forward with 
> softening the real busbars.

Sand paper or emery paper on glass will work well.

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