Advice Requested: Conn Valve Stem Replacement

[MiBrassFS]

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[bloke]

There's a reason I'm a JP dealer. I don't like to carry a lot of stock, and - drop-shipping to schools - I don't have to have them sent here first to look at them to make sure they work.

The only instruments that I worry about a little bit are the tenor saxophones, because the shipping boxes aren't very much larger than the cases. They're shipped working, but they get thrown by shippers.

OK... One other exception:
Low C bass clarinets. Their adjustments are even more finicky than oboes, and I just want to have a look before the customer does, and I would do the same with a Selmer Paris and a Buffet as I would with JP's plastic copy of Selmer and their wood copy of Buffet.

[catgrowlB]

Just to go into a little bit of detail, Yamaha marching brass pistons are completely lead soldered together and then nickel plated. Anyone who might try to silver braze an insert in the top of a Yamaha piston and then re-drill and re-tap is going to be in trouble, because they're going to end up un-soldering the piston from itself.

JP Pistons are stainless steel and tolerances are really excellent.
Yamaha tolerances are also very good but again they're just held together with lead solder and they're not as stable.

Aren't all old classic American pistons (York, Holton, Conn, HN White/King, etc...) more or less made the way Yamaha makes them? Nickel-plated brass or copper pistons, or 'Monel'?

Stainless steel seems nice at first, and is a hard shiny metal that doesn't need to be plated. But I think they will eventually develop rust/corrosion on them over decades, which is worse than plating wear, which can be re-plated.

I think I'd choose nickel-plated brass, or bronze if possible. Or monel pistons over stainless steel, especially over many decades...

[MiBrassFS]

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[gocsick]

Aren't all old classic American pistons (York, Holton, Conn, HN White/King, etc...) more or less made the way Yamaha makes them? Nickel-plated brass or copper pistons, or 'Monel'?

Stainless steel seems nice at first, and is a hard shiny metal that doesn't need to be plated. But I think they will eventually develop rust/corrosion on them over decades, which is worse than plating wear, which can be re-plated.

It is important to note that there are many different alloys of Monel and a huge variety in stainless steel. Putting on my metallurgist hat I am not worried about corrosion in stainless pistons.

Monel is basically a Ni-Cu alloy. It is essentially Cu-Ni German Silver with the compositions flipped about 65% Ni and 35% Cu. There are two primary alloys used for pistons Monel 400 and Monel R-405. The main engineering properties of interest are corrosion resistance and galling and sliding wear resistance. Monel alloys were designed for maritime applications. Monel R-405 is a free machining variety with added sulfur... any is the main choice for “automatic screw-machine stock” and high paced production environments.. but my understanding is it doesn't lap as easily or cleanly as the slightly harder 400. Pros: Won’t rust, great galling resistance against brass/nickel-silver, no plating to wear through, takes an excellent lap and keeps it. Cons: Softer than hardened stainless; if grit gets embedded (poor maintenance, cleaning, or insufficient oiling), it can score a casing.

Stainless for pistons usually means a martensitic stainless steel of precipitation hardened stainless steels. Common austenitic stainless grades like 316L or 304 tend to gall under metal-on-metal sliding unless specially coated. Student horns are often made with 416 SS, hardened & tempered to ~HB 400+, precision-ground and polished. It is very easy to machine on CNC equipment... dirt cheap.. and acceptable corrosion resistance for wear resistance. For higher end instruments typically a precipitation hardened steel is use 17-4 PH, H1025... Actually slightly less hard but better corrosion resistance... really good sliding friction properties.Pros: Hard and dimensionally stable; very wear-resistant; runs nicely in brass or nickel-silver casings; often chosen for durability in high-use horns. Cons: The lower-alloy martensitics (like 416) can tea-stain/pit if neglected in salty sweat; choose 17-4PH if you want more corrosion margin. Dry storage + regular oiling makes the “rust over decades” worry largely academic.

Ni plate - Very slick surface; easy to lap..If pinholes let moisture through, the brass underneath can dezincify and pit.

[bloke]

There's a reason I'm a JP dealer. I don't like to carry a lot of stock, and - drop-shipping to schools - I don't have to have them sent here first to look at them to make sure they work.

The only instruments that I worry about a little bit are the tenor saxophones, because the shipping boxes aren't very much larger than the cases. They're shipped working, but they get thrown by shippers.

OK... One other exception:
Low C bass clarinets. Their adjustments are even more finicky than oboes, and I just want to have a look before the customer does, and I would do the same with a Selmer Paris and a Buffet as I would with JP's plastic copy of Selmer and their wood copy of Buffet.

That other company(s) and their “minimums…”

There’s a school service place here that lists JP as an available brand (I think…), but I’ve never seen any JP branded anything. Folks here on TF seem to enjoy what they’ve bought.

They don't have a whole bunch of cool C tuba stuff like Eastman, but I find that theit knockoffs tend to be as good or better than (in the case of their copy of the Czech Arion tuba, I think the JP is actually a bit better, and - again - I prefer JP marching brass over the "real" Yamaha stuff) those things that they copy. I'm not going to sell as many tubas as an Eastman dealer because of the more limited selection, but the quality is just remarkable, and people really seem to like their euphoniums. They also have a Conn 8D knock off that's really nice... but I know that in the French horn realm there are some other really good Chinese instruments... and a whole bunch of horn players today are of the Geyer school.
Mostly, the stuff is really well made and I can sell it without any headaches while doing all the other stuff that I do. Their Rath licensed trombones are also really sweet, they actually have an entire Rath line and entire "good enough for most people" trombone line that's much less expensive.
I had never either personally examined nor sold their nicer baritone sax, and was really nervous when I was selling one to a high school whereby the band director is a baritone sax player who personally owns a Yamaha 62 bari. They did backflips over the JP, and are now ordering a second one. Needless to say I was relieved, and when I also unboxed it and played it before taking it to them, my eyebrows went up.. it's not cheap. With all the tariffs and everything I have to charge nearly $6K, and that's with a pretty modest markup. That baritone saxophone is Taiwanese, but they also have a Chinese one for several thousand less that some people say is almost as good. I'd like to see one of those as well, but I haven't sold one of those yet. If I liked PT15 or 2250 F tubas, I would be just as happy with theirs as one from Germany.

[catgrowlB]

It is important to note that there are many different alloys of Monel and a huge variety in stainless steel. Putting on my metallurgist hat I am not worried about corrosion in stainless pistons.

I'm fascinated with metals and alloys, so this is interesting to me.

I have a few 'ancient' (like a century-old) tubas with pistons that haven't been replated or rebuilt. Sure, there is plating wear and even some pitting, but once oiled they are smooth and still have good compression! Probably nickel-plated brass.

Monel (as you say, a nickel-copper alloy) sounds great to me for pistons


After seeing many things made of 'stainless steel' over the years actually discolor/stain and sometimes even develop rust (in a less wet environment than stainless pistons), we will see how those various stainless pistons hold up over 50-100 years.....

[bloke]

I've worked on a few Chinese instruments that were supposed to have stainless steel pistons which were just unplated nickel brass.

Monel and so-called "Yamaloy" (which I suspect is monel) are the ones that I have found which attract oxidation deposits from valve casings. It's annoying, but light dry buffing knocks that stuff off.

My own tubas with actual stainless steel pistons (whether Chinese or European) have never discolored at all. I have an encountered any stainless steel Pistons which discolored on customer instruments... though of course the unplated brass cross ports tarnish, collect lime, and the edges of those can collect lime. I discourage this on my own instruments by heavily oiling every time I play.

The old Taiwan made instruments apparently had nickel plated pistons but would collect black stuff off the casings as well, which was sort of odd. I would just buff that stuff off the same way as described above. The tolerances on those pistons never impressed me, which defined that they didn't stick too badly even when they were covered with that stuff and solid black. Now that they've moved over to stainless steel, it seems as though they've tightened up the tolerances without tightening up the accuracy of the workmanship, and I'm having more trouble with those valves when they are brought in by customers.