Magnet Valves

[Tubaing]

Has anyone else ever thought of using magnets instead of springs for valves on tubas?

[tubatom91]

I havent thought of it until just now. But now that I am thinking about it....I think that when you pull a magnet off a fridge (a magnet powerfull enough to use for this application) it seems to jerk when initial contact is broken. I think that magnets have a field of magnetism that is stronger the closer they are to the surface. So, if the valve is left in the open position it will be up close to the magnet and when the paddle/spatula is pushed it might jerk instead of a smooth and even force associated with springs. I do find concepts like this fascinating though and might think about it more later. it might work if you found JUST the right magnet strength and distance inbetween the magnet surface and valve stopper. very neat idea though

[Tubainsauga]

I believe magnets are used as an alternative to springs on some exotic brand of custom flutes http://www.matitflutes.com/ Not exactly a normal example. I think for brass instruments the resistance they would provide would vary too greatly through the throw of the valve (lots of pressure needed for the last little bit of the throw). There is also the "if it ain't broke, don't fix it" mentality. Springs are not that problematic on brass instruments, though they can be on flutes (at least in a band room. Crochet hooks are the key.) On the other hand, I could see if working for rotary valves better then pistons (more powerful magnets but over a longer distance may give better performance, but again it probably isn't worth it.

[Tubaing]

I think that when you pull a magnet off a fridge (a magnet powerfull enough to use for this application) it seems to jerk when initial contact is broken.

My idea isn't having magnets pull the valves to the top, but to push them from the bottom. It would be powered with the repelling force and not the attracting force. So there would be no initial contact.

The idea isn't necessarily for benefit, perhaps just for a little fun.

[Art Hovey]

The attractive or repulsive force between two magnets (or between one magnet and a piece of iron) depends strongly on the distance between the two objects. That means you would have to push really hard to get the valve down the last millimeter or the first millimeter, depending on the design. The elastic force exerted by a spring also depends on the distance between its ends, but less drastically; it's nearly a constant force over the normal range of motion. A magnetic substitute for valve springs would also have to be much heavier than real springs.
Another problem with magnets is the way they pick up bits of steel wool or iron filings and refuse to let go.
When I was very young and stupid I designed a hydraulic valve return system that would exert a nearly constant restoring force, but I soon realized that inertial forces would make it a very poor substitute for good old coil springs.

[windshieldbug]

It would be powered with the repelling force and not the attracting force.

Many tuba players are already repulsive enough.

[Dan Schultz]

....My idea isn't having magnets pull the valves to the top, but to push them from the bottom. It would be powered with the repelling force and not the attracting force. So there would be no initial contact.

The idea isn't necessarily for benefit, perhaps just for a little fun.

That's an interesting concept. You could probably do it with some of the rare earth magnets that wondermagnet.com sells. Give it a shot and tell us how it works.

[Tubainsauga]

To expand on what's already been said, the force exerted from a spring is consistent over, I think, 60 percent of it's compression which is roughly what a tuba valve accounts for (I learned this a while ago, don't quote me on it but I think the idea is right.) To get the same characteristics from a valve you would probably need to have very long valve casings and rather powerful magnets to get them to move consistently throughout the throw of the valve. Likewise, magnetic force is not that easy to calculate as the shape and various other details of the magnet come into play. I still think magnetic linkages on a rotary tuba could be interesting to experiment with if for no other reason than it's an excuse to play with magnets.

[tubatom91]

To get the same characteristics from a valve you would probably need to have very long valve casings and rather powerful magnets to get them to move consistently throughout the throw of the valve.

Maybe it'd work on one of those compensating Besson's. I think it'd be cool to have a push-up effect on a piston. When I made my first post I was thinking more along the lines of rotary valves.

[peter birch]

It would be powered with the repelling force and not the attracting force.

Many tuba players are already repulsive enough.

...but some of are are attractive....

[Roger Lewis]

What I would like to see is a hydraulic system similar to that used on the valve train of the Formula I race cars from Renault. They are so fast and dependable that these motors turn around 19,000 RPM. Just imagine how fast the valve system would need to be to keep up with that. And I'm sure you could set it up for a very light touch.

Probably too expensive though.

Roger

[bill]

Maybe if we used the valve lever to open an electronic circuit and have that charge the valve magnet, we could make it seem seamless. Of course, we might need to have battery powered tubas, then and we might run the risk of running out of juice in the middle of a concert performance but, well, fiddles break strings and all that so . . .

[peter birch]

could lead to the invention of a "player" tuba (like the player piano), add a compressor and a flow meter and we are all out of a job...

[windshieldbug]

Maybe if we used the valve lever to open an electronic circuit and have that charge the valve magnet, we could make it seem seamless. Of course, we might need to have battery powered tubas, then and we might run the risk of running out of juice in the middle of a concert performance but, well, fiddles break strings and all that so . . .

I've broken strings on my string-action Marzan until I had sense enough to convert the valves to direct-action. I'm liking the possibilities of electric, though... "I'm sorry, Maestro, but when we got to that passage, one of the stagehands tripped over the extension cord, and since there ARE NO other tubas to trade with, I was helpless... "

[Tubaguyry]

Likewise, magnetic force is not that easy to calculate...

Calculate, schmalculate. Math and physics and all that jazz are great, but you never know whether or not something will work until you try it. Helicopters aren't SUPPOSED to be able to fly, but they do!

I'm very interested to see if anyone can come up with a working magnet valve. Keep us posted, all you inventors!

[Ferguson]

Helicopters aren't SUPPOSED to be able to fly, but they do!

Yes, helicopters are supposed to fly. It's not magic. Look up the Bernoulli principle. It's also what makes your tuba work.

SF

[tubatom91]

Are the current valve materials even atracted to magnets? Do they have iron/steel in them? or would we have to go to steel valves?

[windshieldbug]

Aren't Spotted Al's extinct yet? Man, they keep promising...

[Dan Schultz]

Are the current valve materials even atracted to magnets? Do they have iron/steel in them? or would we have to go to steel valves?

Modern valves are stainless steel, monel, or brass with nickel plating... all non-magnetic materials. In order for this to work there would have to be a magnet attached to the bottom of the piston and a magnet with opposing force attached to the inside of the casing. I'm thinking that flat, round rare-earth magnets might be the best shot. I think if those magnets are turned 180 degrees they will repel. I don't have time to mess with it at the moment.

[windshieldbug]

Are you saying that his valves didn't suck enough?