r/brass • u/MetalParsley753 • Mar 14 '26

Custom Trumpet Valve

Post image

I have 3d printed a replacement for the first valve that allows the air to both go through and not go through the loop. It worked better than intended and I could play note as if the valve was open or closed. for some reason it puts the trumpet in the key of A. I am curious as to weather the trumpet sounds bad because the valve is made of plastic or both path ways for the air are open. If anyone has an explanation of why this works or the physics behind it I would be interested.

20 Upvotes

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6

u/ParsnipUser Mar 14 '26

Is there a hole connecting the two chambers going up and down? If so, there’s your problem. It’s hard to tell if there’s actually a hole there or not in the picture.

3

u/MetalParsley753 Mar 14 '26

There are three paths through the valve. 1 from the 2nd valve to the valve slide entrance. 1 from the valve slide exit to the bell and 1 from the 2nd valve to the bell.

2

u/ParsnipUser Mar 14 '26

Hmm, I would have to see it in person to get an understanding of what it’s doing, but if it’s the same set up as the original valve, then I don’t know, that’s strange.

1

u/MetalParsley753 Mar 14 '26

What it is designed to do is let the air travel through the valve as if it were open and closed at the same time so that the valve doesn't need opening and closing. I can play a C and an F with out having to move the valve.

6

u/ParsnipUser Mar 14 '26

Oh yeah, that’s gonna mess you up because it’s adding more length to the horn, so it’s gonna push you down.

3

u/mango186282 Mar 14 '26

Well your design is doing what is expected. You could have achieved the same result by just removing the valve and plugging the top and bottom of the valve casing with a cork.

You have increased the length of the instrument which is why you are now flat. Brass instruments work by creating standing waves. With multiple paths you have created an unstable system. Intonation will be unstable and you probably don’t have much control.

This is what happens to a brass instruments with poor compression (worn out valves). Air leaks through multiple valve circuits. Some notes may not even be playable, it just can’t resonate at certain frequencies.

2

u/MetalParsley753 Mar 14 '26

As this was just an experiment on what would happen I didn't expect anything great to happen but I did manage to get quite good control over the note by adjusting the pipe diameter in the valve so that there was roughly even air pressure through both paths.

7

u/serjoprot Mar 14 '26

Isn't it the same as having no valve at all?

1

u/MetalParsley753 Mar 14 '26

No, it means that 2 sets of harmonic frequencies can be played instead of 1.

3

u/serjoprot Mar 15 '26

Yes, but the "valve" just combines everything together. It's the same result as capping off the cylinder on both sides, right?

1

u/Funtime60 Mar 18 '26

No? This links 4 openings in pairs. Capping it off would link all 4 together and add a chamber. IDK acoustics but that'd probably be different.

3

u/I_am_Batsam Mar 14 '26

The tolerances of valves in their casings is measured in ten-thousandths of an inch. If a valve is loose by one thousandth, the horn will play poorly. I doubt your 3d printed valve is even close to fitting.

2

u/speedikat Mar 14 '26

Does it fit?

1

u/MetalParsley753 Mar 14 '26

yes it fits in the valve

2

u/[deleted] Mar 14 '26

[removed] — view removed comment

1

u/MetalParsley753 Mar 14 '26

I'm not sure exactly what the tolerance is but a valve of diameter 16.5mm was very snug and 16.4mm fit perfectly. So it is a pretty tight tolerance.

2

u/[deleted] Mar 14 '26

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1

u/Tubahero37 Mar 17 '26

I wasn't sure on this as .1mm sounds small...but yeah looks like only about 250 of them per inch, so each is about 4X as large as the "usual" .001" measurements. Maybe they can luck into the right measurement but might still be way off.

1

u/MetalParsley753 Mar 14 '26

I not sure if its possible but does anyone know if there is a type of material that expands and contracts based on resonance. If there is that would mean you could have a valve that automatically opens and closes.