Hello, I am a tooling engineer and the use of the low temperature
alloys has been around for a very long time.  The original company
in the U.S. was Cerro Alloys, later bought out by Bolton Metal
Products.  I would not be concerned with using the material but,
as always, work in a well-vented area.

The material that is suggested to use for bending tubing up to,
I think, 1.5 inches diameter, is their "Alloy 158", which melts at 
158 degrees Fahrenheit so it is easy to work with and easy to remove
from the tube after bending.  What really makes this stuff work
better than, say, lead or solder is that when it cools it actually
expands to put pressure on the inside of the tube.  The web address
is http://boltonmetalproducts.com/ 

Anyone can order the material and they sell it by the pound at
$18.13 per pound.  You should quench the tube in cold water after
filling [with the hot alloy] in order to get the expansion to take
place.  If you let it air cool it will not work as good.

When I was in tech school our teacher had made a mold that he could
cast spoons out of the material.  It was his favorite joke to give
someone a hot cup of coffee and there would be one of his special
spoons to add the sugar and stir the coffee.  When the spoon just goes
away the person would look so shocked that the coffee "ate" the spoon!

You can go to the 'Net to see how you can build some neat tube bending
jigs and there are some available in the automotive tool areas.

We also built special tooling to make elbows for the nuclear industry.
In the past they had to make elbows in two halves and weld them
together like a clam shell.  The pipe is stainless steel and 1/2" thick
in some cases.  They had to X-ray the welds and no voids were allowed.

A guy came up with the idea to machine the shape in tool steel, harden
the two halves and then lay a straight piece of pipe in a channel
leading into the bend curve.  They would then clamp the two halves in
a press and a ram would go in and push the 1/2" thick steel up to 10"
diameter into the die and out would come a perfect elbow with no
welding.  That is the way they make the copper elbows in the plumbing
area.  The ends are on an angle when straight and after bending they
come out flat.

This alloy also works great for holding odd shaped parts to allow
machining to be done when you cannot clamp them in a vise.

This is a long email but thought I would throw in my two cents.  There
is always a way to make stuff you need -- just ask and someone will
know how!  I am rebuilding my first player at age 66 just because
I like to work on the mechanical things.  I hope it comes out right;
I'm getting lots of help from great people out there.

David F. Fowler
North Carolina

 [ See http://shop.boltonmetalproducts.com/Bolton-158-formerly-sold-as-Cerro-Bend-LB100004.htm 
 [ -- Robbie