Rebuilding Metal-Stemmed Valves
Written by Craig Brougher (5/21/99)

Because of the problems with players using the metal-stemmed valves over the years which I have both experienced and troubleshot for others, I want to offer this bit of advice to hobbyists who try to rebuild their own. This article is primarily concerned with actions by Standard, Lester, Baldwin, Cable, Story & Clark, Beckwith, Hardman, and the others which used metal stems and press-fit collars.

At the outset, The Player Piano Co. can be a good place to buy parts and supplies, but it is not always the best place to buy valve leather punchings unless you know what you are going to get before-hand, or know what not to use (because they don't). I recommend being suspicious of their plastic coated leathers, plastic synthetics, neoprenes, so-called patent leather (which is not real patent leather) and other valve washers represented as better than leather. Nothing yet has been better than good leather.

When choosing leather for valves, I have never seen this rule fail: Don't use any leather, either corrected calf (meaning that the grain has been taken off the smooth side and the leather wax-finished), or suede that you wouldn't want to wear. It must be beautifully even, reasonably heavy, supple, smooth, and have the proper stiffness, just like the leather removed from the original player.

In metal stemmed valves which have a pressure fit collar for each valve washer-- as in the Standard, Beckwith, and others, you also have a thin metal washer backup plate which keeps the leather from "sucking up" against the inside seat. We could call it a "face washer." Without it, the valve might never "let go" of the inside seat, if the leather were supple and limber enough. This has happened often to those who buy PPCo's leather valve replacements for Standard. Even with the thin shim washer, the leather they sell presently is so limber and thin--bodiless-- that it prevents the valves from working. I suggest not buying it.

Meanwhile, when you rebuild a player, you have to notice the little things-- like, leather stiffness. It is stiff for a reason. It isn't that way by accident. Unless that leather was precisely that stiff and very flat when punched and laid, that valve would not operate correctly. The leather in Standard inside valves was corrected calf. It is about .025 -.030 thick. Shoe leather, some might call it. It cannot be patent leather, or it will stick on tin-plated brass inside seats. It cannot be soft, or it will stretch and distort, and will not release cleanly. And, it must be mounted the same way it was designed, with a little flexibility at the valve stem. That means, the valve washer has to "tilt" slightly on its stem. If it is too "tilty," then it will leak. If it is too "tight," then it will not seal reliably. If it is patent leather or slick plastic (today's stuff), it will not slide to seal, so it will stick on the first spot it touches down on, and leak.

[This is not to discourage some Lester owners , some of which had patent leather valves originally. That was the real patent leather. It was not vinyl coated and sticky to metal like vinyl. It was also heavy-bodied and flat. They don't make it anymore.]

The next thing you MUST do in the case of the press-fit metal stem valves, if you want a successful rebuild, is to back up your valve washer with either the tiny leather seal, or a tight vinyl seal as sold by the Player Piano Co. Notice what comes off the stem. there is a little pouch leather washer about 1/4" dia. It's hole is tight around the metal stem. The reason is because it alone is the stem seal for the valve, allowing the rest of the valve poppet to tip slightly on the stem for flexibility.

[If the total valve seepage of each valve in a player equals only the diameter of a shirt pin, The overall leakage is a bit over what you would have by drilling a 1/4" hole into your pump. A few organ rebuilders have had problems with this tightness requirement, because they are dealing with relatively low pressures and huge, over-designed blowers to take care of leakages they always have. Player pianos don't have 1000% margin allowances. They are designed for a smaller maximum number of playing notes occurring at one time. Above that number of notes, they will drop notes.]

The next point is the fact that some player valves use metal backup plates (the valve washer), and some use fiber. Both will give you problems, today. Here is why. The metal backup plates used by Standard actions were tin-plated brass which reacted with the leather acids to form a "verdigris," or green corrosion, which in turn makes big green lumps under the valve leather. Just one or two of these will disable the player. But you will have over 90 of them, any of which will disable the player. The fiber washer backup plates of similar actions are either red or gray fiberboard. They are worse. They warp. If you don't believe it, then sit them down on a metal or glass plate and using a toothpick, press around their circumferences. They will almost always tip and "click." That means they are not flat. They may look flat. They might fool you. Flip them over and check both sides. If they seem to be "evenly" cupped, they are NOT!! Put a dozen of them on a sheet of glass or formica countertop and tap with the end of a toothpick all around the disk. It will usually click and move around, meaning that it isn't flat anymore.

Player Piano Co. sells both stainless steel washers for the two sizes of Standard valves. Those are the ones to substitute for the "face washer," as well as the backup valve washer. But for the actions which use the fiber valve washers, be sure to throw away ALL red and gray original fiber washers, and buy them from Organ Supply Co. in Erie, PA. The Player Piano Co in Wichita has discontinued those most important parts. I do not understand why. It is their bread and butter...

[It would seem to me that if you are going to sell to a specialized trade, you first must sell the things that nobody else wants to stock for your trade, or you are no longer specialized. But I am not a merchant, so I guess I just don't have good sense in those areas.]

If your red or gray washers are "perfect," and do not tip on glass or metal plate and are optically flat, congratulations. Now throw them away. Because if they haven't warped yet, they will. Thin fiber washers of the original variety are the most insidious thing in the valves of a player piano. The tiniest warp cannot be remedied and will cause even the cushiest valve material to leak, especially at low intensities when you need tightness in a critical way.

The Beckwith player had a Standard-type player action, horizontal valves, but used a thick, very heavy gray fiber washer for an inside valve seat that was recessed in the valve chest. When you unseal and remove it, it warps. From that moment on, it will not straighten back up, regardless what you do. The only way to fix Beckwith's fiber inside valve seats is to sand them flat again on a belt sander, and then smooth them down. I doubt that you will find replacements for those, so we hope that the material has fully responded to all the stresses inside it by now, and that it is through warping. But within a couple of days, it might be wise to have gapped, sealed and seated all your valves in the stack again. How soon or if they decide to warp is anybody's guess. Just be sure the screw holes are tight to help clamp it again.

The tin-plated brass seats, stems, washers, and whatever else you have must be cleaned up. Then coat them with something like dry electrical silicone spray (available at electronic supply stores) or TFE mold release coatings to seal the brass against leather acids which immediately begin on it again and start up corrosion. Be sure that you have removed all verdigris from the brass parts if you reuse them, or it will grow quickly again to stop your player.

Any oil or grease, such as mink oil, Syl-Glide, Neatsfoot oil, Vaseline, Hemorrhoid creme, or whatever else they'll sell or recommend for sealing and preserving valves is verboten in a professionally done player stack having metal valves, because these oils are all lighter than water and have a high vapor pressure index. That means they will redeposit themselves through the player. When that happens, water molecules which travel with the air as humidity are trapped under this molecular film of oil and together with heat and the acidic moisture drawn from the leather, corrode all the metal parts in this type of action, particularly in Southern climates, and humid conditions. Only pure silicone grease will stay put, and will seal out moisture as well as cooking oils in the air, when you lightly coat your metal parts with it, first.

Gap the valves between .035" and .045". Anything under .035" is too slow and too weak. Even an overgap of .055" is better than an undergap of .032". Gapping with a gauge is ok, as long as you know about the leather compression rule. Metal stemmed valves are checked at the stem for travel, not at the poppet face. The gap is determined at the lowest pressure able to lift the valve, not at some higher pressure. That means, practically no compression-- only enough to make a positive seal. So a certain "finesse" is in order, if you are going to be successful on every valve. Unless your pressure is constant and unless the leather nap does not vary, the gaps, after you set them, can vary greatly. I have seen meticulous work with a machinist's gauge vary + or - .007" because of differences in valve compression caused by either the spacers, both of felt and leather, paper, valve leather thickness and nap variances, etc. A home made feeler gauge is usually better than machine tooling, because it allows you a close and personal feel of what you're doing, and you won't trust it altogether.

Usually, in the common vertical valve chest, the finger presses the valve stem up from its outside seat, while the gauge measures the travel to the inside seat. Here too is a potential mistake. The finger is very strong and you don't recognize differences between 2 ounces and 2 lbs., often enough. So while the gauge may be reading correctly, the finger is changing that reading all over the map (nap?). Get a piano action jack spring, mount a little button of some kind in its end to touch the valve stem, and then mount the spring on a little peg set into a tiny "stool" that sits on the outside seat surface. Now each valve will be compressed the same amount. It's really simple, but if you really want consistency you have to plan for it.

When setting the lifters to the pouches, the best way to do this, I have found, is to set 4 or 5 valves from end to end, first, by hand. Then, in the Standard chest, I will find a straight stick that spans the chest and slides on its edges, which I then shim up to just touch the adjustable lifter buttons. That will give me a pouch clearance of between 1/16" and 1/8." Putting a gap between button and pouch speeds the valve's return, which is really the limiting factor of any valve.

The last thing I can advise about doing metal-stemmed valves of this type is precision of movement. If the valve guides allow too much slop around the stems, or if their bushing guides are either damaged, the felt fallen out, worn out, or crusty with tin residue, they won't work well. They will drag the valve and jam it. The Standard valve is a powerful, fast valve because of the very thin contact area on its inside valve plate. If its guides are not well-centered, or if the stem travel is not straight and true, the flexibility you put in the poppet connection will not help. It will not correct for a stem that can jiggle very much. It is the precision of the stem that allows a metal stem valve to work fast and reliably. Horizontal valves in particular are susceptible to tin crust accumulation in their guides and wear and tear on the felted holes. Use a pipe stem cleaner and solvent to remove crust. And if the felt has fallen out or is worn, either replace with new bushing felt or buy all new guides without felt from PPCo. Some guides didn't have felt, originally. On those types, I suggest silicone spray for electronics again. Coat the stems. It is a perfectly dry lube, will stay put, and will protect the tin plated stems from wear.

Craig Brougher

E-Mail to: Craig Brougher
Phone No: 816-254-1693

Other Fine Articles by Craig Brougher
[Ampico A/B Comparison]   [Tuning Pin Tighteners]   [Importance of Valves]
[Hammer Lift Rail]   [Using Hide Glue]   [Regulating Dampers]
[Rebuilding AMPICO Block Valves]

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