Like the Theme valve (discussed last time), the soft peripheral is a medium valve box with pneumatics which adds dynamic expression capabilities to the piano.

And like other expression devices on the piano, it is divided into a bass and treble side. Since it is a single box this means it sits smack in the middle of the pump. The soft expression feature is controlled by two separate buttons, which can be depressed at will by the operator.

When a button is pressed, it opens a small pallet valve under the button, sending a “signal” of atmosphere to the designated side of the unit. This small signal activates a pouch of an inside valve, closing it and choking the amount of air flow to the stack, to a moderate degree. In other words, the soft feature is literally a “choke”. There is a pneumatic on the side of the box, which is in the path of the diverted airflow, linked through two ports. Unlike the valve it closes with a slight delay (it is spring loaded to resist); this is to make the decrescendo less sudden and jarring.

That’s basically it…the idea is that as soon as the button is released the airflow of suction to the stack (and hence the volume level of the piano) returns to normal immediately.

Here’s what the valve box (now with new gaskets and pneumatic cloth) looks like with the panel cover on it.

And finally here it is mounted on the trunk, still open while I do some set up for testing with the pump…

There are a couple of peripherals remaining; this time I will discuss the valve boxes which contain an integrated stack “cutout” (or “cutoff”) and “Theme” activation design.

The cutouts are actually a twin set of valve boxes (at least in my piano they are)  which get mounted on the main trunk of the pump. As I mentioned in the previous post, when the music roll is over, the user switches from “play” to “reroll”. One effect of this action is that the cutout valves are activated, cutting off suction to the stack, which prevents any notes from playing during reroll.

The cutout valves are just standard inside valves, located at the inside top of the box. These valves are the gatekeepers of the suction to the stack. It’s basically a firm disc with a leather facing, on stem which is mounted on a wooden base. The base is glued over the oval pouch, which inflates when the valve is activated. In this case activated means “closed”; the valve is off (open) during play mode.

As you can see in the photo, there is some other stuff going on in the box as well. The Theme valve is packed in here too, at least on this piano (there was a certain amount of design variation, even by the same maker, from year to year). The Theme valve is an extra expression valve which is triggered by rolls which are coded a certain way, known by the name “Themodist”, or other variations.
The Theme coding in a roll corresponds to special “snakebite” holes located near each end of a tracker bar in a piano with this system.

In a Theme piano the stack and pump are divided in half (bass and treble), and when the valve is triggered on one or both sides of the pump, the corresponding side of the stack gets more suction and therefore plays louder. It does this by bypassing the “regulated” suction and connecting the stack to the full power of the pump. That’s about it!

Well, that’s the simplified explanation; HOW the valve operates is something a bit more complicated. Take a look at the following annotated image which is my interpretation (which I believe is probably correct) of how the valve works:

In evaluating the current condition of these boxes, the facings and pouches of the large valves seem* okay, probably due to the minimal exposure to atmosphere over the years. The small theme activation valve is a wildcard, I won’t really know until it’s up and running if the thing works.
The rub is that I would have to completely dismantle the valve box to rebuild that one small valve….which in addition to being rather tedious risks damaging the box itself.

So, in this case I am making a calculated decision to push forward with the box “as is”, with the understanding that the Theme valve may not work as it should. I do reserve the option to return at a later time to rebuild it, all I would lose in that case would be a couple of gaskets.

Depending on who you ask, the Theme function is either a cheap gimmick or an expressive feature to make a roll more musical. It adds a little bit but is still a far cry from the level of expressiveness in a reproducing piano, which has a much more nuanced method of expression.

*to be tested!

Now we come to a rather important unit called the governor.
The unit in my piano actually comprises a governor, accelerator, tempo control, and reroll bypass…here’s what it looks like!

(These are the “before” pictures)

So what’s a governor? What does it do?

A governor is essentially a pairing of a spring-loaded pneumatic and a knife valve. Its purpose is to regulate suction flow to the motor, so that the motor turns evenly at a given tempo.
Because the action of a person pumping the pedals is not always perfectly smooth, there needs to be a way to compensate for this roughness and the governor’s job to do so. Like other aspects of the player action it utilizes a simple yet elegant design. The flow is routed through the knife valve, which is open a certain amount (let’s say halfway, for the purposes of this explanation) under normal pumping.
If the pumper slacks off, slightly (too much slacking will make the music stop!), the governor compensates by sensing the flow pressure differential inside the unit, and opens the valve to allow more access to the main trunk, where there is extra suction stored in the reservoir.
If the pumper gets excited and starts pumping extra hard, again the differential is sensed and the suction pulls the pneumatic (and the valve) more closed, so that it doesn’t make the motor rush.
This all happens behind the scenes with no direct intervention from the user, it’s all automatic.
Without the governor, the motor (and therefore the playback of the music) would be completely at the mercy of the pumping technique of the user. In many cases, this would mean a bad performance!

The tempo control is commonly paired with (or in close proximity to) the governor. Every pianola has a tempo control lever, which is adjusted by the user. The lever is connected to a slide valve in the unit, which moves in a linear way over an inline port to the motor.
Essentially, when you move the lever to a higher tempo, you are opening the valve to let more suction reach the motor. When the lever is moved downtempo, the valve gets closer to closing, effectively choking the motor and slowing the music.

The accelerator is very much the same idea as the tempo, except in my piano it is meant to be used in “real time”, as opposed to the tempo control which is supposed to be set at the beginning of the roll. The accelerator is also spring loaded to default to a neutral position; whether you press the lever to “accel” or “ritard”, it will spring back upon relase.

Finally, there is a bypass valve, for reroll. When the roll finishes, the “play” lever is flipped to “reroll”, and a couple of things happen as a consequence. Firstly, the direction of the transmission is reversed, so that the roll rewinds. In addition, the suction to the stack is cut off, so that no notes are triggered upon reroll. We wouldn’t want to hear the music playing backwards!
The rotary valve is switched off (this valve is pictured back in the pedal pneumatic post); the signal to the pedal pneumatic is cut off, so that the damper lift is not triggered constantly as the roll rewinds.
Finally, the bypass valve in the governor unit is opened, so that the motor gets maximum suction and operates at full speed on rewind. Otherwise, it would take as long to rewind a roll as it would to listen to the song – and unacceptably long delay!

Even though the construction of the unit is fairly straightforward, it’s important not to overlook anything and to get it all right.
Make sure the knife valve is still mated well, and lubricate with graphite. Recover the slide valves if necessary, and lubricate those too (lightly). Recover the pneumatic and make sure it’s tight, before remounting on the unit. Ensure the various port channels and compartments are sealed, so that there is no inadvertent leakage when the valves are closed.

There really isn’t an obvious way (to my knowledge) of testing the governor’s function independently, outside the piano. So you won’t know what you’ve got until everything is back in place and connected up… but, if you have done diligent work, you should be fine!

And we’re back! Now that the head is done I am moving on to the peripherals. These are defined as any stand-alone components not directly attached to the main trunk or the stack. In my case this means the pedal pneumatic, the governor, the loud/soft button control box, and the theme/ cutout boxes. These last items are technically attached to the lower trunk, but they still have to be rebuilt and verified separately.

Let’s start with the pedal pneumatic. It’s got a couple of different features from previous components, like two inside valves (secondary), and a double pneumatic.

The input to the pedal pneumatic is tubed to a manifold rotary valve underneath the keybed, which connects back to the tracker bar input, the pedal button control. Both of these inputs are shut off when the rotary valve closes during the “reroll” or rewind stage, when the user toggles the switch.

The suction supply is a larger input, because this pneumatic has to generate a fairly large degree of force, and do it quickly, in order to lift all the dampers. The top of the pneumatic is connected to the pedal prop rod via a fulcrum lever. When the pedal input receives atmosphere input, it sends a cascading signal to the pneumatic to close, which in turn raises the dampers.

See diagram from old Standard literature:

Now for the rebuilding. As before, remove old soft materials (unless you can salvage pouches, as in my case), then do your cleaning and sealing.

I will do a post on inside valves separately, that’s a specific topic which covers a fair bit of theory.

The double pneumatic needs a slightly different approach, when recovering. Instead of one pivot point a double pneumatic has two, so the cloth must be first put on one outer edge to the middle edge, then to the other outer edge. Not rocket surgery, really.

The double pneumatic is also double hinged, for strength, as well as spring loaded. You will save a fair amount of trouble if you make an index for your spring holes in the hinge end of the boards. It can just be a piece of acetate or whatever, a “map” to know where to puncture through the cloth, once the hinge end is recovered.

So once the regasketing and recovering is done, I still need to get these two inside valves sorted to complete the unit; until then I will just set it aside and move onto the next peripheral.

The last component to rebuild on the “head” section is a small valve box which is a primary booster for the Theme signal. The “Theme” feature is specific to certain types of player pianos, I will explain about that later.
For now we just need to be concerned that it works, although there is not much to it; just a pair of primary valves and pouches, inside a small box.
As per other operations, take it all apart, use a screw map to stow screws, carefully take apart the primary valves by chipping away glue blob at the top of stem, then a modest but firm blow with a small hammer (and punch, if necessary). It will come apart in two pieces.
Pull off what gasket material you can by hand, then scrape until you are at the glue residue level. Then lap surfaces on sandpaper over flat glass (or other dead flat surface). You don’t need to go to fine on the sandpaper, 120 grit is fine as a little roughness will help the glue joint.
Once it’s all apart and prepped, you’re ready to start rebuilding, with fresh materials!

Now it’s time to measure, mark, cut and glue some new gaskets. I mentioned about gaskets last time, so the method is described there. Once it’s all cut, glue in place, using enough but not too much glue, applying quickly if using hot glue –as you should!
Pull the old leather off the valve facings, resurface the top face (the bottom should not have been glued, if Standard style), and put new leather facings on, being quite cautious not to get any glue on the outside of the facings, which will render them useless. Again, enough glue, but not too much.
Reassemble the valves on the top section, using a gauge to space the travel gap at 1/32″, the default distance for Standard style outside valves. John Tuttle gave me a tip that you can make one from an old ivory keytop tail, so that’s what I did! It works! A little dollop of glue on top of the button at the stem will keep it locked in place. It doesn’t take much.
Put the box back together. It may look something like this ( I haven’t fitted the dust cap, as this is cosmetic and blocks the view of the primaries for testing):

Once reassembled, it’s testing time. You probably don’t need a suction pump from this, just a tube with mouth power (shallow breaths in!). When the valve is receiving atmosphere signal, it opens and lets atmosphere pass to the output. When the valve input is closed off (meaning that there is roll paper covering the corresponding holes on the tracker bar), it should receive nothing, and therefore output nothing.
The inputs should be the lowest horizontal row of nipples on the valve box, so when those are plugged and unplugged under suction, they should pop up and down accordingly.
It’s a little cumbersome to check all this in tight quarters, with a noisy vacuum cleaner as a test pump, but it can be done. Once you’re happy with the performance of this valve box, time to move on. In my case it means that the head of the stack is done, yes!

It’s a nice milestone to have the motor, transmission, spoolbox, tracker and valve box ready for final assembly. Now let’s dig into some peripherals!

Gaskets keep everything nice and tight. They keep the suction in where you want it, and the atmosphere out. Since all valve boxes are made of blocks of wood, and even well-mated wood surfaces are not airtight, there must be a membrane of some sort which is suitably compressible, but also durable.

The traditional candidate is split leather. When leather of proper quality and consistency is used, it does both jobs well, and leather to wood with hot hide glue is a match made in heaven. There simply isn’t a better way to work other than the original way.

However, there are alternatives.
When I say alternatives, I want to stress I am not taking about the adhesive part! For my opinion on glues, see previous post here.

I was speaking of a “modern” gasket material of neoprene. Plastics get a bad rap in the piano industry sometimes, because in the beginning, the technology was inferior and the product didn’t age well (plastics were introduced into pianos as early as the 1930’s). However, plastic materials have come a long way, and like every product there is a range of quality.

Traditionalists will turn up their noses at this idea, but that’s fine. Tradition has its place, and I respect it where I feel appropriate, but this doesn’t prevent me from trying new things.
In the case of neoprene, for a material that was modestly cheaper, easier to source, slightly easier to work with and – most importantly!– well-performing as leather, that seemed good enough for me. Time will tell!

My main concern with this type of product in the long term would be elasticity (being permanently compressed and not expanding in drier weather), and structural integrity (starting to disintegrate over time). On the question of integrity, since a gasket is –by definition– always sandwiched firmly between two pieces of wood, the oxidization problems should be minimal.

The material comes in sheets and you just cut what you need, in the most efficient way you can manage. For cutting straight lines I use a steel rule and a rotary cutter, on a cutting board designed for the cutter (“self-healing”).

For punching holes I use a handheld punch, which works well for screw holes (the most common kind). For anything larger than that, you really need a punch set to do a neat professional job.
For small and medium surfaces mark all holes on a given side with chalk (lightly) and then dry fit the gasket to the surface. The perimeter outline can be rough at this point, doesn’t need to be perfect now. Release the piece and place the gasket on a punching board. The cutting board worked for me for this material, because it’s so light, you just press it out by hand.  I would not have used a hammer to drive the punch on my nice cutting board!
Then do the screw holes, however you want. When all done check against the piece, and assuming it’s good, go ahead and glue it on real good (the neoprene I use has two different sides, it’s the “skin” side which gets glued down).
Finally cut away the perimeter edge with a pair of shears or long scissors. Easy!

The only thing to watch for is that the thickness tolerance is kept faithful, when you replace gaskets. If you are putting neoprene in place of a gasket that was originally designed to be leather or blotter paper, the compressibility will not be identical, so this is something to keep in mind. If you are not duplicating the original in terms of material, you should still attempt to match it in terms of dimensions, wherever possible.
Gaskets can be made from any number of things, but traditionally it has been leathers, cork, blotter paper or other cardboard type papers. You can choose to use any number of solutions, but don’t use the wrong material for the wrong reasons.
The thing about quality leather is that it is getting harder to source. It’s just another one of those commodities that has become more scarce, for several reasons. That was part of my decision to go with neoprene.
But using cheap and inappropriate materials only to save a few nickels and a few minutes is false economy. Spare a thought for the person who will have to do the next restoration, it may even be you! Trying to scrape off disintegrated plastics mixed with modern glues is truly drudgery of the worst kind. Don’t let it be you!

No photos this time, but I will illustrate gasket use in the following post!

This is going to be a lot shorter than the preceding post, for a couple of reasons.

Firstly, half the battle with a component like the tracking device is simply understanding how it operates. You can’t do proper rebuilding and testing/troubleshooting without this knowledge.
It took me a few days of fairly steady thinking on this topic, for it to start to sink in.

The other thing is that there is not a lot new here, in terms of components. I’ve covered pneumatics, I’m probably not doing pouches (however this is covered extensively in the Reblitz book), and I will specifically cover gaskets (simple) and valves in future posts.

Like the other components, good sealing is a must for proper function. This means the internal channels, the recovered bellows, the mating of the primary valve facings to the box, and good gaskets.

Once all this is done, it’s a matter of reassembly and testing. Here’s what it looks like back together:

And so let’s make sure it does what it needs to do.

First get a suction supply going, to test. In a perfect world you have a test pump from an old reproducing piano, but barring that, a regular shop vac will suffice (it’s what I used). Just regulate the suction so that you are in the 5″ water range (a vacuum dial gauge is good for this, or a home made water vacuum gauge). I made a laughably cheezy regulator, with a clothes pin and some elastics, to hold a piece of tubing a little bit outside the mouth of the vacuum. MacGuyver would be proud!

The drawback to testing with a vacuum is the noise. Apart from being generally grating, it also makes it difficult to hear leaks when troubleshooting. But, we must use whatever tools at our disposal.

Hook up the suction supply to the appropriate nipple on the box (it should be the one that is not otherwise identified). Then run the following series of tests:

1) Close off all 4 inputs (you don’t need to tube to an actual tracker bar to do this). Is the system balanced? You should see the pneumatic cloth get sucked in slightly in the bellows, but other than that, they should stay pretty much where they are. More on that in a moment. Assuming all good, continue.

2) Open the outer holes. Still balanced? Good!

3) Open the inner holes too, all holes open. Still balanced? Okay!

These tests check the balance of the pneumatics, if the bellows list to one side or another, or if they are otherwise not behaving identically to each other, we have a problem! The problem is a leak somewhere, so you’ll have to track it down and fix it. Do it now, show no mercy to leaks whatsoever. It will not ever work if it leaks, so if it means taking everything apart and checking each component separately, just do what it takes!

Once we have established balance in equilibrium, let’s check it in disequilibrium.

4) Close all holes again, then open just one outer hole. The bellows should track accordingly, moving smoothly in concert to one side. When you cover the hole, they should return to default halfway position. If they move quickly but don’t return reasonably quickly, this is a troubleshooting tip, likely a blocked bleed. Try the other outside hole in the same manner.

5) Same as step 4, but concentrate this time on only opening each outer hole (not at same time) just a little – halfway or less. The bellows should still react and begin to shift as soon as the hole is opened partially.

6) Cover only the inner holes, and repeat steps 4 and 5, one inner hole at a time. The bellows should again perform the same way.

Assuming it does all these things well, you should be good. But if there is something which makes you squirrelly happening now, just check again and again, repairing if necessary, until it looks like it should.

One thing I noticed on my first attempts, was that the right pneumatic would noticeable jerk when getting suction signal. It is a quirk of the design that the pneumatic is only mounted on the shift box with a single screw. This is not ideal from a “no motion” perspective, so I had to dismount it (which ruined my gasket, it had to be cleaned off and replaced), then check for flatness, and then make sure the pneumatic sits perfectly straight on the box, supported equally on both top and bottom, when you glue (or shellac) the gasket back on.

Thankfully the pneumatic had an access port for the screw, so I was just able to open that up to pop off the pneumatic, I didn’t have to ruin the the recovery job I had done.

This does remind me however, that there are possibilities for some real bouts of tedium and frustration when troubleshooting. What’s more is that the closer you get to the end, the chances of time-wasting increase, unless you take the time to really check your work at every stage. I must repeat this mantra to myself constantly!

Here’s a video of a testing session I did:

So, that’s basically it! Just reattach whatever mounting blocks or other hardware to the unit, and set it aside until whole action reassembly.

On to the next thing!

Actually, let’s take a quick side tour to gaskets….TBC

Although not as eye-catching as the motor, the auto tracking device is just as necessary and just as sexy. In fact the tracking device is usually the most mechanically elegant feature of the whole dang piano! In his introduction to the Standard Tracking Device (p 143), Art Reblitz calls the Standard in particular “one of the most sophisticated pneumatic mechanisms in any piano”.

The tracker in my piano is very nearly the same as a Standard, it operates on exactly the same design principles, especially in the valve box (also called shifter box). However in terms of appearance and layout, it is essentially an Autopiano tracker (see image below). Indicators are the bottom bleed chamber, as well as the vertical orientation of the pneumatics, plus another particular feature I will mention later on.

Note that while the general principles of the following information apply widely to most “automatic” pneumatic trackers, there are specific differences which may apply.

The tracking device keeps the paper rolling on the “straight and narrow”. This is vitally important, because if the paper becomes misaligned with the tracker bar as it unspools, the music becomes real bad, real fast. If we continue with an automotive analogy, the motor and the transmission are self-explanatory. The tracker can be considered the steering wheel. Imagine therefore, trying to drive your car, and the wheels did not follow what you were doing as you turned the steering wheel: it would be interesting, but not in a good way!

And so, let’s dig in a little bit and try and figure out how this thing works. I admit it has taken me some time to understand this thing. There is an awful lot to digest here, so understandably it may take you a while to get through it. Alternately you can watch a video by John Tuttle here. In fact, I recommend that you read all this, then watch the video, then do it all again!

Once it’s all taken apart, we see that it consists of two outside (primary) valves, six pouches and seven channels – three of which are almost too small to be considered true channels.
The 2 primary valves are paired with a set of primary pouches. There are two “wannabe” inside valves paired with what are called the “cutout” pouches. These are essentially two thick wooden discs (which look like primary valve caps) glued on top of the cutout pouches. Over head of the of the cutout pouches there are two slightly larger pouches, cleverly called “overhead” pouches. The overhead pouch has the power to override the cutout pouch, due to larger surface area (in my case 1 1/8 vs 7/8 diameter).For channels, we’ve got 4 “inputs”, which is where the four nipples on top of the valve box are tubed directly to the 4 specified holes in the tracker bar. Inputs 1 and 2 both lead to a matched but independent channel which runs underneath both the cutout pouch and the primary pouch. Inputs 3 and 4 are essentially direct feeds to each overhead pouch well (again, independent of each other).On the underside of the valve box (on my model, at least) there is a suction supply, which is just a small hole in the valve well with a nipple outside to hold the tube.Finally, there are two interior channels connecting the primary valves to the pneumatics. The primary valves determine if the pneumatics get suction or atmosphere, so these can be considered the “outputs” of the valve box.

Confused yet? I can’t blame you, after having read all that!A picture is worth a thousand words, so here is what the inside of the valve box looks like:

The first thing that will help simplify matters is to notice that the valve box is a stereo set. In other words, you really only have to understand “half” of what is happening, and the other half does the same thing.
The second thing is that even though the 4 inputs from the tracker bar can theoretically give up to 16 different permutations, for practical purposes it’s actually less than that.
If we work backwards and follow the path, we can see that the tracker linkage (which controls the position of the music roll, via the spool cam) is effected by the movement of the tracker pneumatic. The tracker pneumatic moves (e.g. opens or closes) depending on what “signal” (suction or atmosphere) it is getting from the output of the valve box. This signal is switched on or off by the primary valve. The valve is controlled by the primary pouch. The primary pouch is arranged inline with the cutout pouch, and both of these pouches are fed by the exterior hole of the tracker bar hole set (inputs 1 or 2, as labeled by me). The overhead pouches are fed by the interior holes of the tracker bar, which are again labeled 3 and 4 respectively on my box.

States of play, of one side of valve box (meaning one valve only):
1) Both (inner and outer) holes of tracker bar are open (no roll paper is covering). The inner hole triggers the overhead pouch, which overpowers the cutout pouch. Even though the outer hole is open, the cutout pouch is overpowered, so the valve is not opened, and the suction goes through to the pneumatic.
2) Both (inner and outer) holes are closed. The overhead pouch is not triggered, but it doesn’t matter because neither is the cutout or the primary pouch. Again, the valve stays down (closed), and the pneumatic keeps receiving suction.
3) Inner hole closed, outer hole open. The overhead pouch is not triggered; the outer hole allows air to pass to the primary pouch and lift the valve. The valve opens, closing the suction chamber and letting atmosphere into the pneumatic. This is what could be considered “default” setting
4) Outer hole closed, inner open. Unless the roll was damaged in a very particular way, this situation would never occur. In theory it would mean that suction continues to that pneumatic, as in case 1.
Note that for the first 3 scenarios, as long as the same thing is happening on both sides of the tracker bar (and valve box), the system can be considered balanced, which means the pneumatics are acting equally in concert, and not trying to move the piano roll left or right to compensate.
When there are differences between the sides, we will have an unbalanced system, so we have to revisit our scenarios.
5) One inner hole closed (on one side), other three holes open: atmosphere is fed to the open holes, for practical purposes it is the uncovered inner hole that leads to the overhead pouch, which will expand and let atmosphere pass to one pneumatic. The other pneumatic will still be getting suction, so it will pull the atmosphere pneumatic back into balance.
6) One outer hole opened, other three closed: the outer hole will allow atmosphere into its channel and open the valve, allowing atmosphere into one pneumatic. Again, the system will automatically rebalance.
7) One pair of inner/outer holes opened, other pair (on other side) closed: this would be an unusual situation, most likely resulting from a damaged roll. As explained by John Tuttle here, if both holes on one side are temporarily opened, the tracker does not try to correct, but just keeps status quo. Whether this was a planned design outcome, or just happy accident, I don’t know!

If that is not sufficiently confusing, another key fact is that the inner/outer holes are cross connected to the valve box inputs, so that the inner and outer hole from the same side of the tracker bar are not inline on the same input channel. Why? Because that’s the way it was designed, and that’s the only way it can work! I spent a bunch of time thinking about this, but John Tuttle gave me the above explanation, and really that’s what matters. It just is.

Other related facts:
The outer holes are for standard (or larger) sized piano rolls, standard size being 11 1/4″. The system will still work with slightly narrower rolls (i.e. the system can function using the inner holes only), but if there are rolls which are significantly wider than standard, the system is not well-equipped to respond to roll drift in this case.
Finally, the “particular feature” on my tracker is that there are no bleeds for the overhead pouches. This is related to the fact that my tracker bar scale apparently allows some air into the outer holes at all times, the holes are indexed this way on purpose. So not only is the overhead pouch larger, but due to lack of bleed it really comes down hard and fast, to override the cutout valve and keep the linked pneumatic under suction.
Furthermore, John reminded me that the self-cleaning bleeds are also self-regulating as well; the more that a valve pouch opens, the more the corresponding bleed opens as well, which means the resistance to opening increases concomitantly. Interesting stuff!
Your head probably hurts a little from having read all this, so let’s leave it there, and get into the specifics of rebuilding next time.

Sources: Player Piano Servicing and Rebuilding. A. Reblitz. Vestal Press, Lanham, MA. 1985.
“Player Piano Pointers”. Auto Pneumatic Action Company. New York, 1917. (Note: this is a public domain document, available from AMICA, with membership)

So, we have the motor components all done.

Let’s reassemble the motor and get this sucker running!

If you have been careful in documenting how you took everything apart, then putting it all back together should be a snap! If you haven’t….well, consider it a free lesson from the school of hard knocks. As we say around these parts: “that’ll learn ya!”

To summarize:

• stripped down the trunk, repaired any damage, sealed channels, lapped and lubed the face
• recovered, lapped and lubed slide valves
• repaired, rehinged and recovered pneumatics
• clean and polish all hardware
• replace and lube all bushings of various flanges, arms, valve guides

And so. After verifying each individual pneumatic independently for airtightness, let’s glue them back on to their home base. Probably good to get that out of the way, right off the top. You don’t need to get fancy or have an awful lot of pressure in this situation; here’s my solution:

Now with that done, test again, to make sure pneumatics are still tight. Close them and then seal all the trunk intake channels. If they offer stiff and continued resistance as you pull them open (firmly, but gently), and you don’t hear any hissing, leaking noises, you should be good. If ever you get the odd leak at this stage, you can probably bet (by process of elimination) that it is between the pneumatic and the trunk. If you can localize it you should be able to then neutralize it, with a few drops of Phenoseal — ask me how I know! (wink, nudge)

Now remount the hardware, again being careful not to bend the crankshaft as you reassemble everything. Next the slide valves. And you’re done! Or are you?

Last but not least, let’s check the timing. As with comedy, timing is everything! There is a mechanical sweet spot to be had, where the motor works at optimum efficiency (just like any combustion engine, including the one in your vehicle).

There are a couple of different ways to look at this, but basically you want all the valves set the same, and you want them all to begin the “powerstroke” just after the valve closes. You can refer to Reblitz 41 for more details, or also John Tuttle’s tidbits here, or here.

Once you feel confident, you can take it for a test drive! It should run fairly smooth, even at very low speeds. You can use a vacuum cleaner if you don’t have a test pump, but note that this is not the ideal testing device. It may make the motor appear to turn in a lurching manner. I have read that most of the good motors are overengineered to run even if not perfectly regulated, so as long as you get it as good as you can, that’s probably good enough!

Here’s what mine looked like, as an initial test run after rebuild:

One of the final tasks on the checklist before motor reassembly is rebushing. There are many, many bushings of different descriptions and purposes in a player piano (or a regular piano), but they are mostly variations on a theme.

A bushing is a piece of material (usually sturdy cloth) which creates a sort of “buffer zone” between a moving part and a stationary part. For example, anywhere there is a pin or rod that rotates, chances are good that there is a bushing around this part. A bushing must be the right size: too thick and it will induce unwanted friction, too thin and the moving part will not have sufficient support, causing inefficient mechanical motion and probably unpleasant noises as well.

For the present post, we are referring specifically to the bushings in the motor. You will want to redo all of these bushings, especially the ones that come into contact with the crankshaft (which is most of them). This motor has got to run a long time, so let’s freshen up those bushings and keep it tight!

Let’s start with connector arms and valve flanges. Remove the old cloth. Before we get too far ahead, you might as well clean out the bushing holes of old residue with a properly size drill bit. The fit should be snug, but don’t ream the hole any larger.

Now measure the old cloth. You will need to match the dimensions of the original bushing, the key word being original. There are two dimensions to watch for here: thickness and width.
The length of the bushing will not have changed, so when you cut a strip of cloth, the width of the cloth must match the length of the old piece. If ever the bushings are damaged or missing, you can approximate by remembering some geometry: the circumference of a circle is π x diameter. In other words, if you measure the span of the hole, multiply by 3 (and a smidge), and cut your cloth strip to this width, it should be a pretty close fit!

The thickness is tricker; measure the thickness with calipers or similar gauge, and then realize we must account for wear. Depending on wear, we may need to add ten to twenty thousands (of an inch) to replicate original cloth.

Once you’ve got something you can work with, tear a strip (good quality cloth will tear cleanly and evenly, just as well as cutting) of the proper width, as long as you need.  For bushings that go in a hole (in a block of wood), cut a bit away to make a “tip” on the strip and pull it through the hole, almost the entire way through. If you look at the cloth sitting in the hole, the two sides should touch each other, but without having the cloth bunch up in the hole. If there is a gap, your cloth is too small. If it bunches: Too big!

Then put a reasonable amount of glue (you will figure this out on your own) on the cloth and pull it the rest of the way into the hole.  Assuming you’ve used hot hide glue, let it set up for a few minutes (while you do the next, and the next), then double back before the glue hardens completely and trim the excess cloth.

There is a trick to this, and it involves a sharp instrument like a new razor blade. Nothing screams “amateur!” like sloppy bushings cut with a dull blade. To avoid dislodging your new bushing with the blade, insert a stand in mandrel (like a wooden dowel) of proper size into the bushing hole. Hopefully it goes without saying that you don’t use your crankshaft as the cutting mandrel!

For bushings which can be put in place without the above method (e.g. open cavities), you should be able to cut to size before gluing in place, as is the case with the following slide valve arm flange bushings.

And whadya know – John Tuttle has a video on this subject too! I’ll let him offer his perspective again – click here!

There are still more kinds of bushings, such as those for the side guides of the slide valves. These will be a snap, after having done the rotary ones. They are just strips of cloth!

Once your various bushings have all been done, collect everything (back in the correct order), and get ready to put the motor back together. Almost there!