David,
Thanks for the heads up on the Bernzomatic TS-8000. I am using a 20+ year old
all brass Bernzomatic head which has never let me down before, but it could be
a contributing factor. It does put out a heck of a long beautiful blue flame
though.
I chose to support the copper bars on the hack saw blade teeth because there is
the least contact between the part and the support to wick away the heat. I was
afraid that brickwork would absorb some of the heat. I did unsuccessfully
search my garage for some old refractory blanket.
Cleaning - Good reminder about sandpaper on glass - Thanks. I learned the
"glass" trick when rebuilding a 1960 Triumph TR3 engine and took the crank
thrust bearing down to the minimum specified gap by sanding a mismatched set of
standard and oversized backing plates down on a piece of glass and also
blueprinted the pump by reducing the pump rotor baseplate clearances on a
sandpaper/glass setup. Great tip!
Jack
-----Original Message-----
From: David Scheidt <dmscheidt@gmail.com>
Sent: Sunday, August 9, 2020 7:21 AM
To: Jack Brooks <JIBrooks@live.com>; shop-talk <shop-talk@autox.team.net>
Subject: Re: [Shop-talk] Annealing Copper bars
On Sat, Aug 8, 2020 at 5:51 PM Jack Brooks <JIBrooks@live.com> 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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