On Oct 9, 12:50*am, "anorton"
wrote:
"Steve B" 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.

I saw the program where they were making trombones, they used the soap
and water mixture there. I think sand has to be finer stuff than
playground sand, probably more like some grades of molding sand. The
classic production method for small tubing is Cerrobend as a filler,
melts in hot water. Wall thickness will have a lot to do with how
sharp a bend can be made, tubing is available in a lot of different
wall thicknesses. And I'd definitely run the stuff through a torch to
anneal it to dead soft before starting anything. Doesn't need to be
red heat, just enough to discolor it. It DOES make a difference.
Will probably take a number of tries before you get the right
combination.

Stan