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