Turning trumpet valves

[Eric Gourieux]

I've given myself the challenge of turning a trumpet and making it playable. I have most of the components turned except for the valves. My dilemma is what material to use for the valves. Although I'd like to use hard maple to match the rest of the trumpet, I'm concerned about movement of the wood and binding of the valve. The tolerances have to be very tight for the valves to function, and, although it won't be played very much, I want a functioning trumpet. I'm in the process of making some valves from Corian glue-ups but would prefer wood. Does anybody have any suggestions on what wood tends to move the least with humidity? Would an oily wood such as African Blackwood move less? I also have Osage orange and holly. Any suggestions? I'll post the final project when finished.

[Brian Brown]

What about Argentinian Lignum Vitae. Water resistant, hard, and used for decades for marine bearings. I worry about how it would slide in the valve bodies, but the same goes for all woods. You definitely want something that won't expand.

[Allan Speers]

I think it's a brilliant idea! - but like Brian said, no expansion can be allowed.

Maybe you could treat all valve parts with the same stuff used to stabilize pen blanks & such?


As far as what wood, if you're NOT treating it then it also has to be hard. Mesquite & Ebony come quickly to mind. Very hard & very stable.

Black Locust & Osage Orange are almost as good. IIRC, also Purpleheart & Cocobolo.

And yeah, Lignum Vitae, or Ipe, but those would be pretty hard to machine into valves.

Ebony makes the most sense in terms of a musical instrument, just because it's already a standard fro clarinets & such, but I'd probably go with Mesquite, as it has less tendency to crack over time.


If you're treating it, then one of the very light species will be even more stable than Mesquite, but I forget which are best. Maybe Hemlock, or Cedar? Teak?

There's a species - characteristics calculator online somewhere, but I forget what it's called. Try Woodweb.com, it's probably there.

[Allan Speers]

UPDATE:

Two useful calculators are at Woodbin.com

"The Shrinkulator," for only stability specs, and "The Wood Picker" for less stability details, but more overall parameters.


There's also another one somewhere else that I prefer, but the name completely escapes me.

[Brian Kent]

The lignum vitae seems promising since it lasts for ship bearings and is self lubricating.

[Dan Masshardt]

How big are these? I could send you some argentine lignum pen blanks to use.

[Allan Speers]

I don't think the self-lubrication of Lignum Vitae is going to be enough lube for trumpet valves. Those valves have to move lightning fast, with very little mechanical effort. That's why trumpet oil is super-thin.

Lignum slides well on other wood & metal, but it's not SLICK. It could actually impede how the real valve oil works.

[Dan Hintz]

I don't think the self-lubrication of Lignum Vitae is going to be enough lube for trumpet valves. Those valves have to move lightning fast, with very little mechanical effort. That's why trumpet oil is super-thin.

Lignum slides well on other wood & metal, but it's not SLICK. It could actually impede how the real valve oil works.

Not to mention it's not metal-on-metal for slides... usually it's a felt ring (or similar) on the piston that slides up/down the valve body.

[Dan Hintz]

Send a message to Bruce Boone... a buddy of his makes some really sweet custom trumpets, so he may be able to give you a few pointers.

[Shawn Pachlhofer]

I didn't play trumpet, my brother did. I recall the felt being just under the screw cap to seal the top of the valve and the valve being metal on metal

I played trombone - and I can say for a fact that a trombone slide is metal on metal.

[Brian Myers]

Shawn is right , the valve on a trumpet is metal on metal. The felt sits between the top cap that screws down and the key your finger presses.

[Art Mann]

I would sure like to see a photo when you are finished!

[Shawn Pachlhofer]

Shawn is right , the valve on a trumpet is metal on metal. The felt sits between the top cap that screws down and the key your finger presses.

now that I think about it - the felt wasn't there to seal anything. It was there to soften the metallic "clunk" of the valve return to the full open position.

Something else for the OP to consider - if you use a "heavy" wood like lignum vitea, you'll need a stiffer spring to return the valve to the open position.

[Dan Hintz]

Just looked up a picture... you're right, metal-on-metal. I haven't played for over 30 years, so yeah, my memory is a bit rusty.

[Allan Speers]

Something else for the OP to consider - if you use a "heavy" wood like lignum vitea, you'll need a stiffer spring to return the valve to the open position.

Good point.

And since the valves must be as light as possible, I would narrow the choice of wood to not just stable, but resistant to cracking when thin. That rules out Cocobolo & Ebony.

Another thought: The top of the valves must have screw caps. (threads) There's likely no other way to close them against the tension of the springs. How on earth can you do that with a thin tube of wood? Maybe it would be acceptable to just use metal valves, and veneer them?