Pistons - brass, vs. nickel, vs. Monel

[Dan Schultz]

Even though I am a repair professional with an extensive mechanical engineering background... I've never fully understood the virtues of the different piston materials and how they apply to music instruments.

Brass comes in many alloys. There are approximately 35 varieties of stainless steel and 5 types of Monel.

I prefer nickel-plated brass pistons because they seem to perform well for me and lend themselves well to being refit.

I know this is a stretch. But... I would like for you to respond ONLY with REAL professional experiences or REAL technical knowledge.

[Lee Stofer]

I think the idea of copper-plated pistons was that 1) copper build up quickly and relatively inexpensively, 2) copper-plated pistons in good condition do have a nice, soft feel, and 3) the copper pistons would wear down, not the brass valve casings, so that the pistons could be re-plated and fitted time and again. That practice came from a time when people repaired and re-built everything they could, before the idea of a "throw-away" culture came into being.

I view raw nickel-silver and monel similarly, in that they will work well-enough if in good condition with tight tolerances and are well-lubricated. The thing with raw nickel-silver is normally that either they're very old and need plating and refitting, or they're pretty new and were not fitted well, so they need plating and re-fitting.

My experience leads me to believe that nickel-plated pistons, although the most expensive to do right, are the finest pistons available. I prefer the feel, and have worked on over-50-year-old horns with nickel-plated pistons that are still in great shape. Nickel is very hard, and being a basically inert metal, it is harder for platers to work with. And, if the process is rushed or compromised in any way - well, having nickel-plated pistons that are peeling and pitted is just about the worst.

[Lee Stofer]

I think the idea of copper-plated pistons was that 1) copper build up quickly and relatively inexpensively, 2) copper-plated pistons in good condition do have a nice, soft feel, and 3) the copper pistons would wear down, not the brass valve casings, so that the pistons could be re-plated and fitted time and again. That practice came from a time when people repaired and re-built everything they could, before the idea of a "throw-away" culture came into being.

I view raw nickel-silver and monel similarly, in that they will work well-enough if in good condition with tight tolerances and are well-lubricated. The thing with raw nickel-silver is normally that either they're very old and need plating and refitting, or they're pretty new and were not fitted well, so they need plating and re-fitting.

My experience leads me to believe that nickel-plated pistons, although the most expensive to do right, are the finest pistons available. I prefer the feel, and have worked on over-50-year-old horns with nickel-plated pistons that are still in great shape. Nickel is very hard, and being a basically inert metal, it is harder for platers to work with. And, if the process is rushed or compromised in any way - well, having nickel-plated pistons that are peeling and pitted is just about the worst.

[basstbone64]

Well said, Lee.

I would add an observation that stainless alloys have a tendency to acquire a staining, which has a drastically negative effect on function and feel. Some makers have solved this issue, but many cheap imports have not. I do not know if this is simply an alloy change within "stainless", or something else.

From a manufacturing standpoint I can see the appeal of working with Monel. It machines nicely in CNC setups, and can be precision ground to size with only minimal lapping required for final fit.

Additionally, I have observed many horns with Monel pistons that have become worn with use. It usually seems like the casing wears faster than the (Monel) pistons.

[Dan Schultz]

In addition to about twenty years fixing stuff... I also spent about thirty years in manufacturing engineering.

Others have already mentioned that nickel plate is probably the best choice but the process requires very strict procedures and can be difficult.

Stainless steels or Monel materials are more expensive than brass but switching to them was probably done to circumvent some of the manufacturing difficulties of plating in hopes of producing the same product for less money. Any time I see the phrase 'new and improved' I always take it with a grain of salt.

Unless the Chinese manufacturers start paying attention to the micro-finish on the outside of pistons and inside of bores... I don't care what kind of material they throw at the problem, things just aren't going to get any better.

I doubt if there are very many folks selling Chinese products who even have a clue what 'micro-finish' means. Until they figure a few things out and start demanding better quality... we're just not going to have many choices.

[basstbone64]

Bloke, yeah, you're right, it's Monel that stains; I'm not sure what I was thinking...

[Dan Schultz]

I'm not trying to be "the guy who's right" (and I really don't know very much at all...REALLY...NOT)...just reporting what happens with stuff that I deal with.
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Dan,
You and your spouse should come down for a winter visit (fireplace, scotch, walks through the woods, etc...) and check out a couple of pieces of equipment.
The difference between German stuff and the best-made Chinese stuff...??
The Chinese are willing to listen.

Check your email!