32 replies to this topic

[Cheater]

Dave,

In non-slot arenas, I have heard of filling tubing with sand or other granular material before bending to keep the tube from collapsing at the bend. Brass instrument repairmen use some sort of soft, meltable metal to fill brass tubing before bending it.

[team burrito]

I also heard they fill the tubes with water and freeze it.

It might be easier to use solid brass rods instead of tubing. Just a thought.

[tonyp]

How long do you think it would take to fill .063" pin tubing with sand?

[Bill from NH]

That would depend on how fine your sand was. But I'd rather stick a piece of .032" wire in it, make my bends, then try to pull the wire out without deforming my bent tubing.

[Phil Irvin]

Many moons ago... we used to cap/plug one end, fill with salt or fine sand, stick a peice of piano wire in the other. If using heat, like a small torch, you can use the sand and bend. If not hot, salt will work. It's a pain to do hot but bends much easier. Salt works on softer stuff. The sand/salt will not compress and will not let the tubing kink.

I have not had good luck with the springs that go around the tubing. On sharp bends they can be hard to get off.

Have fun..

Phil

[Phil Smith]

In non-slot arenas, I have heard of filling tubing with sand or other granular material before bending to keep the tube from collapsing at the bend. Brass instrument repairmen use some sort of soft, meltable metal to fill brass tubing before bending it.

Greg,

There's a "How It's Made" episode about trombones. They froze water in the tubes before bending them. I think the big manufacturers use more efficient methods (I believe Yamaha uses high pressure water). The manufacturer in the show is Shires, a high-end, low volume builder. HERE it is on YouTube.

Here's another twist. This "How It's Made" episode shows the making of a Getzen (a medium size builder) trumpet. They add soap to the water to make the ice pliable.

I was talking to one of the band instrument repairmen I use about making saxophone necks. He mentioned using something like what you mentioned to bend them, although it seemed like it was a clay or wax substance.

A high-end brass instrument is a work of art. It's something you don't appreciate until you study one and think about how it was made.

[Terry]

I've seen this technique used in restorations of older Indy Cars by two different metal fabricators to form larger diameter tubing. It could best be descrided as "pipe sculpting". Very cool stuff to see.

[Cheater]

Here's some further info on the low-temp (158 degrees F) melting metal alloy used for bending tubing as well as for other uses. This is the product used by at least two brass instrument repair shops I know.

The generic name is Wood's metal, which is a compound of bismuth, lead, and a few other low MP metals. Commerical names of the product are cerrobend, bendalloy, and pewtalloy.

Wood's metal