On Sun, 09 Oct 2011 20:46:47 +0100, Newshound
wrote:

On 09/10/2011 16:59, wrote:
On Sat, 8 Oct 2011 23:50:36 -0700, "anorton"
wrote:


"Steve wrote in message
.. .
I have some 3/8" copper tubing that I need to bend at a tight radius. Like
2". I have the spiral bender, and another hand held type, but can't find
either. Next week, I gotta get organized. In the meantime what's the best
way to bend it? I've heard of putting it full of sand. If I do that, do I
bend it around something round, or just bend it slowly and cautiously?

Steve

I have tried the sand method and it did not work well for me. The classic
way to make the sharp bends on trumpets and such is to fill the pipe with
melted pitch and let cool. Another method is to fill with a water-detergent
mixture and freeze it. The detergent keeps the ice from becoming hard enough
to burst the pipe. Don't ask me what the right detergent concentration might
be.
How about filling with melted paraffin wax and then just melt it out
after bending?

I don't think that would be strong enough, I think it will just extrude
and the pipe will flatten. Molten lead is another option; there used to
be low melting point alloys specially for this (Cerrobend, in the UK).
Non-trade name is Woods Metal.
works just fine if you start with tube a bit longer than you need,
fill 1t 100", and crimp both ends of the tube shut before bending.
Also works best if the tube is at temp where the wax is still
"Plastic" - not totally hard.

Full of grease works too, but it is a lot harder to clean out.
Tallow would likely work too, and it never gets as hard as Paraffin. -
again, perhaps not as easy to totally clean out??