Question for the rotory masters...

[iiipopes]

Is the spec quoted density or weight? Those are similar, but completely different specifications.

[Tubaryan12]

Tubaryan12. Right, cubic feet ft. not square. But Chuck was really talking about cubic inch.

My bad...I guess I should have been more clear. I should have said Chuck means cubic inches as I'm sure you meant cubic feet.
This one's for me

[Chuck(G)]

As an aside, stainless is actually lighter (0.287 lb/cu ft.) than yellow brass (0.308 lb./cu. ft.).

Chuck, you might want to check your numbers. Brass is closer to 534 pounds per square foot.

That's cu. inch. Sorry, it was early and my brain wasn't revved up to speed.

[Rick Denney]

Is the spec quoted density or weight? Those are similar, but completely different specifications.

I don't follow. Density is just mass per unit volume. Weight is the force exerted by gravity. Therefore, the units of weight are force (pounds) and the units of density are mass per unit volune (pounds-mass per cubic inch). Given that Chuck's values were pounds per cubic inch, that would be density.

You can't know weight until you know the shape of the object. But density is a material property independent of shape.

If you are meaning the difference between pounds-mass and pounds-force, it doesn't matter if the rotors in question are on the surface of the earth.

Rick "fun with units" Denney

[Chuck(G)]

If you are meaning the difference between pounds-mass and pounds-force, it doesn't matter if the rotors in question are on the surface of the earth.

IIRC, the Customary unit of mass is the "slug" not the pound.

[The Big Ben]

I was thinking (that's dangerous):

Would it make sense to use something cheap (i.e. an ebay french horn) to 'shake down' the processes of making a rotor valve before attempting an expensive tuba? A beat-up old Conn 4D can be had for $100 sometimes and the mechanism is similar.

Granddad could "prototype" on the french horn and then, once he figures out how to do it, then do the tuba (or not)

An idea....

[iiipopes]

Is the spec quoted density or weight? Those are similar, but completely different specifications.

I don't follow. Density is just mass per unit volume. Weight is the force exerted by gravity. Therefore, the units of weight are force (pounds) and the units of density are mass per unit volune (pounds-mass per cubic inch).

Of course it is. But since the posted nomenclature was inconsistent, that's why I asked. It's been sorted out at this point.

[Daniel C. Oberloh]

Is the spec quoted density or weight? Those are similar, but completely different specifications.

I don't follow. Density is just mass per unit volume. Weight is the force exerted by gravity. Therefore, the units of weight are force (pounds) and the units of density are mass per unit volune (pounds-mass per cubic inch). Given that Chuck's values were pounds per cubic inch, that would be density.

You can't know weight until you know the shape of the object. But density is a material property independent of shape.

If you are meaning the difference between pounds-mass and pounds-force, it doesn't matter if the rotors in question are on the surface of the earth.

Rick "fun with units" Denney

Double rotors for a tuba with hollow valves; solid stainless or solid brass, they are still going to be quite a bit heavier then rebuilt originals.


Daniel C. Oberloh
Oberloh Woodwind and Brass Works
Seattle, WA
206.241.5767
www.oberloh.com

[bububassboner]

We have brass and stainless steel coming at the end of the week. I'm going to start just by making a copy in both metals of an old Yamaha single trigger bass trombone and seeing 1) if I can make a good copy and 2) checking out the difference between the two metals. I was going to ask later this week but since it's up now, what do you guys think for the F tuba since the rotors are hollow making the rotors for that out of stainless and then drilling out the inside of the rotor to make it hollow then welding a top for the rotor then elecrtopolishing the top of it to make it smooth?Also if you guys think there is a better way to put the top on let me know. My grand-pa's work got a top of the line CNC lathe two weeks ago and he thinks this will be easy on that.(I hope so)[/quote]

[Chuck(G)]

Sounds like the project is coming along.

You probably don't need to patch over holes drilled in the top or bottom of the rotor to lighten it

I'd be kind of interested to see if a ball thrust bearing on the rotor bottom would improve action.

Keep us posted!

[MaryAnn]

Hey Chuck,
What was that strange horn beastie you showed a picture of all taken apart? From the paddles it looks old, and I don't see any valve slides that look like F slides....and there is where I got stuck.
??
MA

[Chuck(G)]

Hey Chuck,
What was that strange horn beastie you showed a picture of all taken apart? From the paddles it looks old, and I don't see any valve slides that look like F slides....and there is where I got stuck.
??
MA

MA, you'll need to refresh my memory--and are you certain it was me? I've got a memory like a steel sieve. When the wind blows, my head sounds like a calliope...

[Daniel C. Oberloh]

I thought this thread would never come up again.

Even though I think your going about it the hard way and are up against a project that is far more involved then you really understand, I think it is great that you are giving it a try. I really do think that stainless is overkill and complicates the project in ways that cause issues with the work that will need to be done to the valve casings in order to get a proper fit and seal. Trying to fit a new DOUBLE rotor to an 80 year old casing is going to be real difficult (unless you get lucky ), I know because I have done it. Tapered rotors, tapered spindels, tapered casings, port alignments, etc... will all need to match up exactly at the same time and then be tweeked a lot to get them to work smoothly. It would be more straight forward if you were making new casings as well. Forget about any welding or soldering on the new stainless rotor. If soldering or brazing need to be done in your fabrication process, brass will be a better material for the job and if you still want it more corrosion resistant, nickel plate it.

I have included the URL to a page on rotor fabrication for a hollow, cylinder design I have been playing with. Perhaps it will give you some ideas for your project.

http://www.oberloh.com/gallery/rotaryva ... cationpage


Lets see some pics

Daniel C. Oberloh
Oberloh Woodwind and Brass Works
www.oberloh.com

[joh_tuba]

I would love to know how this turned out!

[J.c. Sherman]

There's been a great deal of very good advice given here... Here's what I think FWIW...

1) Just send me the tuba then you won't have a problem... I'll take reeeeaaal good care of it

2) But assuming you want it fixed rather than disposed of : ) Dan has the proper solution. Period. However, if it was my beast...

3) Get some Meinlschmidt double valves, brand new. No plumbing, just the valves. I believe Dr. Young's magnificent double tuba used those valves, but he got them from Gronitz. Either way, the action was fabulous and had a carbon fiber core and were lightning fast a wonderful! Unless you're going into production of full valve sets from now on, save the headache. Solder on the old plumbing and enjoy.

4) Alex Fs are spun gold, for me, unless you have the older, larger bore instruments with the more parabolic taper to the bell. Then, toss it in a dumpster or swedge the valve bearings and keep it as a trophy and get a more modern one ; ) But that's my own opinion, worth what was paid for it.

J.c.S.

[joh_tuba]

FYI, this thread is over three years old. I just brought it back up.