Since I work in a machine shop, I have been thinking about this. My guess is that...
1 valve tubing material is selected. Oversized od.
2 tubing for ports matched to desired bore size.
3 port holes are milled.
4 port tubing is shaped and finagled into the valve tubing.
5 port tubing is silver soldered.
6 excess port tubing trimmed off.
7 caps soldered in.
8 valve is ground to exact OD (SS) or undersized (brass) for plating.
9 plated
10 polished
All of these operations are within the capacity of my workplace. .... I wonder if I should try making a valve.. just contemplating.
For those who are familiar with how this is done; does the process I listed sound right? Or close..
Re: Exactly how are piston valves made?
Posted: Wed Feb 18, 2026 9:20 pm
by bisontuba
Re: Exactly how are piston valves made?
Posted: Wed Feb 18, 2026 11:59 pm
by TxTx
Dan Oberloh has posted some pretty detailed piston valve repair reels on Facebook which show a good bit of what you surmise. Pretty neat.
Re: Exactly how are piston valves made?
Posted: Wed Feb 18, 2026 11:59 pm
by TxTx
(Whoops! Managed to post this twice).
Dan Oberloh has posted some pretty detailed piston valve repair reels on Facebook which show a good bit of what you surmise. Pretty neat.
Re: Exactly how are piston valves made?
Posted: Thu Feb 19, 2026 8:21 am
by Grumpikins
Great. Thank you.
Re: Exactly how are piston valves made?
Posted: Thu Feb 19, 2026 8:34 am
by bloke
The plating step can be skipped if the outside material is made of something that doesn't tarnish.
Monel seems to pick up brass tarnish from the casings which results in green/brown deposits that have to be removed eventually.
Stainless steel doesn't seem to have this tendency.
Plating is a PITA as far as final machining (prior to final fitting) is concerned, as it is thicker on the tops and bottoms of the pistons (polarity).
Non-plated pistons tend to be less trouble.
Rather than being machined slightly undersized (to allow for copper strike and nickel), they can be machined to "just" fit into the casings, and then "worked" into the casings until the tolerances are enough to allow for swift movement.
Plenty of people talk about nickel-plated pistons having a nicer "feel", but that only applies to those manufactured at the very highest level (nearly a lost art)...certainly not to (just as an example) those Japanese marching instruments' pistons. Properly fitted and textured stainless steel pistons are wonderful. (Also, consider that such a large percentage of players' valve casings - and even pistons, sometimes - are coated with scale and with scum in the adjacent porting as well as in the bottom caps - including "professionals' " instruments, so it's a bit difficult for those people to offer legitimate comparison opinions.)
