Piston Questions

[shawnv]

I've got some questions for you more experienced folks on here.

1) Has anyone here ever tried making their own piston? Mostly I'm curious how feasible it is to make a replacement piston. I see older horns missing parts somewhat frequently and occasionally they're missing a piston or two. I imagine it's cost prohibitive in most cases, but if someone had the desire how difficult do you all think it would be.

2) It seems to me like more and more things are being made out of carbon fiber. I've been reading up on how it's used in Formula 1 racing, Rifle Manufacturing, and (to bring it home to music) it's even been used for Sax Necks and Orchestral String Bodies. Do you think it's possible, and if so would it be desirable to try making a piston out of Carbon Fiber. I could see some issues here with cutting holes for the ports and getting it seal well.

3) As an alternative to Carbon Fiber what about a titanium piston? I know Titanium is expensive and difficult to work with but it is possible. From what I've read the biggest issue with titanium specifically would be oxidation when it comes to hard soldering the port tubes into place but from what I've read on some welding forums this can be solved by doing the work in an Argon atmosphere.

The main reason I'm asking is because in the past I know a few people who were trying to make their piston assemblies as light as possible. I've messed around with different materials myself to try and make lighter stems and buttons. It seems like the heaviest part would be the piston itself and that's where the most loss in weight can be made. What do you all think?

[LargeTuba]

Making pistons is super difficult, and even harder to make good pistons.

Mike Johnson started making his own pistons and it took several years for him to get it right. Getting a piston assembly from Germany isn’t too expensive.

Good luck if you want too, it will probably thousands of dollars of equipment.

[the elephant]

You would need a pretty good-sized CNC mill and lathe with turret-type tool posts to get the tolerances and accuracy needed for tuba-sized pistons. You would need to make assembly fixtures. You would need to use the standard materials unless you want to spend a LOT of money and time developing patterns and assembly techniques for CF, or specialized tooling to cope with titanium. Then you would need a very long time to work out all the details. You would have to destroy a lot of material until you finally got it right, and ended with a functional set of pistons.

Also, there are others out there doing this right now with whom you would have to compete for a share of what is a very, very tiny pie.

[bone-a-phone]

I'm a trombone player, so I'm not so familiar with pistons. But I'm also an engineer, so i know processes and materials.

The valve casing and core have to have mating surfaces that can be polished. The pistons also need passages through, which are complex in shape, but can probably be cast, and then press fit into the stainless tube. Threaded cap on the top and

The casing assembly could be cf, with standard brass ports and sleeves molded in place. This would simplify making the valve block, as it could be made in a single part instead of a dozen fiddly pieces soldered together.

[bloke]

cast of what?
how heavy would it be?
Could air pass through it
expansion rate of cast inserts?

[bone-a-phone]

Kanstul rotary valve cores are put together from pieces, joined, then turned on a lathe. This makes lighter valves. The same idea could be used on pistons. They'd take more time to make, but they'd be lighter.

[the elephant]

That’s how they are currently made. Pistons are hollow tubes with three bits of tubing and end caps.Essentially that’s it.

[bloke]

I admittedly scanned the post, but saw some words that hinted towards a solid core design...
...thus my questions.

If I completely misread (as - again - I scanned) I apologize.

[2nd tenor]

That’s how they are currently made. Pistons are hollow tubes with three bits of tubing and end caps.Essentially that’s it.

That’s my understanding too. I’ve always wondered whether casings and pistons are bought in items or manufactured by the instrument maker ??

[shawnv]

Thanks for the input everyone. I have almost no experience with carbon fiber and my experience with titanium is limited to the simpler operations of turning, facing and cutting and tapping threads, but I've been been able to get away with HSS and a good cutting fluid. It hadn't occurred to me that the tolerances required for good pistons would need some of the more specialized tooling I've heard about and CNC machines. I was hoping maybe you could make piston fabrication happen with a manual lathe and enough trial and error. I figured if anyone had it would be one of the pros on here.

[Beyond16]

It hadn't occurred to me that the tolerances required for good pistons would need some of the more specialized tooling I've heard about and CNC machines. I was hoping maybe you could make piston fabrication happen with a manual lathe and enough trial and error. I figured if anyone had it would be one of the pros on here.

Of course a manual lathe is what you want for building valves. CNC would only be after perfecting a design using prototypes built manually. I'm sure some of us here play instruments built in factories that never had electricity, let alone CNC: http://www.oberloh.com/gallery/Connfactoryimages.htm
F. E. Olds started out with this lathe: http://rouses.net/trumpet/oldslathe.htm
No carbide tooling back in those days either.

[the elephant]

CNC makes everything much faster and easier. A manual lathe takes years of training to master well enough to build valves. CNC speeds the learning process up considerably and then guarantees repeatability. Also, you can record your plans and share them over the Internet to get help from someone without ever leaving your garage shop. A manual lathe, in the hands of a novice (such as myself), allows for the making of many nifty items, but repeatability would be difficult, and repeatability is key to making parts that are interchangeable, as they would need to be. There is no point at all in making ONE set of pistons. If you invest that much time and effort it is in order to make MANY sets of pistons to get a return on your massive outlay of time and $$$$$ learning to make pistons. If you want to make a single set of pistons they don't even need to match. You don't *really* need a lathe, either. Just order up tubes of the necessary thickness with corresponding OD/ID clearance (about .008" or so) Nd lap them together. If you bother to get a lathe, learn to use it, and then make something as complicated and with as many handmade parts as a set of pistons, why not save the years of prototyping and just spend the extra for CNC, which, again, greatly speeds up the learning curve?

What you MUST have, though, is a mill that can drill out all the ports in the cases and piston bodies so that they actually line up correctly. ALL the companies who made instruments used a mill and a lathe, and as soon as technology showed them a better, faster, and cheaper way, they adopted it — or eventually, they went out of business.

Seriously, you could simply make them using a very sharp scraper and a jeweler's saw. but WHY WOULD SOMEONE DO THAT?

By the way: You DO know that a CNC lathe can be operated as a manual lathe, too, right? If you buy a lathe you can order it with both manual controls *and* CNC. You can retrofit CNC to an old Atlas. You can add manual knobs to a modern "CNC-only" lathe, too. I was assuming that ANY CNC lathe one of us would use to make valves would include manual knobs.

Lathes are tons of fun. I intend to have one by the end of next summer, and it will be manual. I will add a complete CNC setup to it as soon as I become proficient at using it for my specific needs. I plan to get a mill following the same path. I will be making piston valve sets in two years and hope to sell a few of them to help cover my expenses.

It's going to be a fun journey. I think I will end up making some excellent valves to help supply the Frankentuba community. But I expect that I will produce a lot of crap for some time, HAHAHA!!!

[Daniel C Oberloh]

Yeah, I've made pistons on a few occasions. The last set I made were nickel plated over nickel-silver and brass. These were to replace a set of stainless steel pistons for a MW Thor tuba that were messed up along with the cylinders. The replacements were 20% lighter and far smoother with much easier spring action. A lot of work to make but considering I have a reasonably well tooled machine shop and rebuild valves for many other repair shops, its not that much of a stretch .


DC Oberloh
Oberloh Woodwind and Brass Works
Seattle, WA

[Grumpikins]

I have a question about martin wilk pistons, how do tou identify them? As in, i bought a used tuba and the pistons are very nice. Are they really good manufacturer pistons, or aftermarket.... all i see on them looks like a date stamp.

Sent from my SM-J327VPP using Tapatalk

[2nd tenor]

Yeah, I've made pistons on a few occasions. The last set I made were nickel plated over nickel-silver and brass. These were to replace a set of stainless steel pistons for a MW Thor tuba that were messed up along with the cylinders. The replacements were 20% lighter and far smoother with much easier spring action. A lot of work to make but considering I have a reasonably well tooled machine shop and rebuild valves for many other repair shops, its not that much of a stretch .


DC Oberloh
Oberloh Woodwind and Brass Works
Seattle, WA

If the way that you did this work is recorded in any way then I for one - and I’d be surprised if I was alone on this - would love to see and read more, please.