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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