Valve Replating vs Replacement

[sirisobhakya]

For a worn valve, what is the better thing to do: valve re-plating or purchasing a new valve core? Do electroplated brass has the same hardness and wear resistance as the solid, machined brass in the original valve core?

[Matt K]

This is going to largely depend on the values that you have. In some cases, cheaper to replace. In some cases, cheaper to replace the casing AND the core. (E.g. there was a number of drop in replacements for Conn/Blessing 88 for $125 from Instrument Innovations not too long ago. Sometimes used ones for various horns pop up as well etc.). In other circumstances, such as your horn not having a replacement valve available... it's conceivable. Depends o your tech and how bad the damage is and what the material is.

[ghmerrill]

Since rotary valves typically (if not exclusively) aren't plated in the first place, is RE-plating them something that's actually done? Moreover, if a rotary valve were to actually need replacing/replating because of wear, wouldn't that mean that there was something really seriously wrong with the valve (casing or rotor)?

[Matt K]

Since rotary valves typically (if not exclusively) aren't plated in the first place, is RE-plating them something that's actually done? Moreover, if a rotary valve were to actually need replacing/replating because of wear, wouldn't that mean that there was something really seriously wrong with the valve (casing or rotor)?

In laymens terms, because that's really only the level I understand it, they plate it with something sturdy like nickel silver and then buff it down until its the correct shape again.

[JohnL]

Since rotary valves typically (if not exclusively) aren't plated in the first place, is RE-plating them something that's actually done? Moreover, if a rotary valve were to actually need replacing/replating because of wear, wouldn't that mean that there was something really seriously wrong with the valve (casing or rotor)?

It's much more common on French horns. Obviously, replacing a single valve or an entire cluster is going to be a much bigger deal on a horn than on a trombone, so a rebuild is usually the go-to option for a horn with worn-out valves. Given that the valves see a great deal more use, leaky valves are more common on horns, too.

From the Atkinson Brass website:

Valve Plating and Repair:

Disassembly of valves and slides and levers.
Steel stamping numbers (1, 2, 3 and 4 ) on all levers, valve caps, top bearing, rotors, stop arms and stop plates.
Cleaning and degreasing of valve rotors, horn body and slides.
All plating necessary to rebuild your valves to new condition or better. All valves are hand lapped to exact tolerance.
Removal of all vertical and horizontal end play.
Cleaning and degreasing again of horn body and slides.
Careful assembly of valves.
New corks, strings, and springs are installed.
Test play 4 octaves.
Results are quiet, smooth, fast and tight valves.

Price: $299.00 per valve (for post war Horns)

Osmun Music offers a similar service.

Note that no reputable company will even attempt a rebuild on a valve or valve cluster if they feel that it's too far gone or is fundamentally flawed in some way that the rebuild process would not resolve.

In laymens terms, because that's really only the level I understand it, they plate it with something sturdy like nickel silver and then buff it down until its the correct shape again.

I think they do the initial plate-up in copper, turn or lap them slightly undersize, replate with nickel, and them lap them in.

[ghmerrill]

I've never seen anything on any of my rotary valves that looks like plating, and I've had the valves out of s couple of tubas, a euph, and a couple of trombones. It looks like raw brass to me.

[ghmerrill]

Okay. From that spec this looks like something that would be done in a rebuild -- not as original assembly.

[JohnL]

Okay. From that spec this looks like something that would be done in a rebuild -- not as original assembly.

Yup. It's kind of a "value-added" thing.

[Bonearzt]

Okay. From that spec this looks like something that would be done in a rebuild -- not as original assembly.

Correct, although there are one or two high-end horn makers that either plate their rotor cores or ports, or machine them from nickel-silver.

"Replate" is a misnomer as you are thinking. And it's not generally a fatal flaw that will result in a rebuild need, actually not really sure how they would wear in the main body as the only real metal to metal contact in on the bearing surfaces. But older Conns 8D horns, especially, really benefit from a complete rebuild.

I've sent a couple of customers to Osmun and their horns have come back perfect!! Jim Backer is a master at rebuilding rotor valves!!!.


Eric

[ghmerrill]

... actually not really sure how they would wear in the main body as the only real metal to metal contact in on the bearing surfaces.

Maybe they don't wear it in -- because, as you say, how would you get it to "wear", and wear properly? Maybe they just do REALLY careful honing or machining of the rotor and casing (independently) in some way. That would be really expensive. On the other hand, I HAVE lapped my rotary valves and seem to have achieved an increase in smootheness. But I think that all that got really lapped was the bearing surfaces on the top and bottom.

I would note -- and not trying to be excessively picky here, but just as an observation -- that the quote from Atkinson doesn't say exactly WHAT is plated and WHAT is lapped.

Osmun, on the other hand is explicit about "honing of casings" and "build up of the existing rotors" which seems to strongly imply plating the rotor surface.

I'm curious where Osmun drills the "oil ports" that are offered as a service. The description of "in the rotor bearings" isn't very specific. It sounds like this means drilling a hole in the side of the upper bearing. And it sounds like a fun thing to do, but how would this be an improvement over applying oil in the usual way at the top? Is the argument that putting the oil in on the shaft from the side would result in better distribution of the oil on the interior of the bearing. I'm not feeling that this is very convincing.

[Bonearzt]

... actually not really sure how they would wear in the main body as the only real metal to metal contact in on the bearing surfaces.

Osmun, on the other hand is explicit about "honing of casings" and "build up of the existing rotors" which seems to strongly imply plating the rotor surface.

I'm curious where Osmun drills the "oil ports" that are offered as a service. The description of "in the rotor bearings" isn't very specific. It sounds like this means drilling a hole in the side of the upper bearing. And it sounds like a fun thing to do, but how would this be an improvement over applying oil in the usual way at the top? Is the argument that putting the oil in on the shaft from the side would result in better distribution of the oil on the interior of the bearing. I'm not feeling that this is very convincing.

Yes, Osmun will first hone the rotor and casing , after measuring I'm sure, to ensure trueness and will also check the concentricity between the two bearings to make sure they are tru to each other. Then the rotor is plated, depending on the extent of buildup needed, with a copper base, then silver, then a hard nickel for wear resistance. Each time honing & lapping to fit the casing.


Regarding the drilling of oil ports, I believe they do something similar to what King and Holton maybe?, used to do. The spindle shaft under the stop arm is/was drilled out and small holes drilled into this bore to allow oil to enter farther down into the bearing area. My 78ish 4B has this and also is threaded with small Allen screws to "force" the iol into the bearing surface.
There's another horn tech that machines grooves onto the bearing surfaces also allowing oil to penetrate further into the bearing.
Both these procedures ensure a better lubrication of the bearing surfaces than merely placing oil at the end of the bearing & hoping that it will work it's way in.
I'll try to find the website for the horn tech, might describe it more clearly.

Eric

[JohnL]

Most Olds rotors have oil ports in the spindle shaft on the stop plate side of the rotor. Given the design of the rotors, it's pretty much a necessity.

[ghmerrill]

Okay, I can see how that would work. Seems pretty clever. Kind of, sort, of almost creates a micro-reservoir of oil like the valve cap does on the other end. But do they do the same thing at the bottom bushing as well? You'd think that would be even easier since you already have the cap to hold the oil.