In the wind...

April 1, 2015

Valve jobs, ring jobs, and protection

Most faucets and spigots have rubber washers that act as gaskets. When you turn off a faucet, the washer is compressed, sealing the opening to the pipe and stopping the flow of water. If you turn faucets too hard when shutting off the water, you compress the washer more than necessary—not too big a deal, except the washer will squish and wear out more quickly.

The smooth operation of your automobile’s engine is all about controlling leaks. Piston rings, which are metal washers that seal the pistons against the cylinder walls, isolate the combustion chamber above the pistons from the lubrication of the piston rods and crankshaft. When the rings fail, the oil from below splashes up into the combustion, and now you’re “burning oil.” That’s what’s going on when excessive black and stinky smoke is coming out of your tailpipe. You need a ring job.

Above that combustion chamber are the valves that open to allow the air/fuel mixture from the carburetor or injector in to be ignited by the spark plug, and those that open to allow the exhaust to escape after the cylinder fires. (I know, I know, you diesel guys are waving your arms in the air, saying “OO, OO, OO . . . ” We’ll talk about diesel combustion another day.)

The valves are operated by the camshaft, which is also lubricated by the engine oil. If the valves leak, fuel and exhaust can trade places, and the engine’s operation gets screwed up. You need a valve job.

Perhaps you’ve had car trouble caused by a worn timing belt. That belt turns the camshaft at just the right ratio to the engine’s revolutions, so that intake valves open, letting in the fuel before the spark plug ignites it, and exhaust valves open after the firing, letting the exhaust out. My car’s engine has eight cylinders, and at highway speed, runs at about 2,500 revolutions per minute, which is 41.6 revolutions a second. All eight cylinders fire with each revolution, so there are 332.8 valve openings (and closings) each second. That’s cutting things pretty close. But we sure expect that engine to start every time, and to run like a clock hour after hour. Say you’re driving three and a half hours from New York to Boston. To get you there, you’re asking for 4,193,280 precisely timed valve repetitions. It’s a wonder it works at all.

 

It’s all about the holes.

I like to describe the art of organ building as knowing where to put the holes. Organbuilding workshops include immense collections of drill bits. My set of multi-spurs goes from half-inch to three-inches. They graduate in 64ths up to one inch, 32nds up to one-and-a-half, 16ths to two-and-a-half, and 8ths up to three inches. I have two sets of “numbered” bits (1-60 and 1-80), one of twist drills from 1/16 to one-inch, graduated by 64ths, and one set of “lettered” bits (A–Z).

If you’re interested in knowing more about those sets, follow this link: www.engineersedge.com/drill_sizes.html. You’ll find a chart that shows the numbered, lettered, and fractional sizes compared to ten-thousands of an inch: #80 is .0135, #1 is .228, just under ¼ (which is .250). If you have all three sets, and mine are all packed in one big drill index, you’re covered up to nearly half an inch in tiny graduations. 

Why so fussy? Say you’re building tracker action parts, and you’re going to use #10 (B&S Gauge) phosphor bronze wire (.1018) as a common axle. You want the axle to be tight enough so there’s minimal slop (no one likes a rattly action), but loose enough for reliable free movement. A #38 drill bit is .1015 B&S Gauge—too tight by 3/1000s. Next one bigger is #37, .1040. That’s a margin of 22/1000s, the closest I can get with my sets of bits.

 

And there are lots of holes.

Lots of the holes in our organs allow the passage of wind pressure. In the Pitman windchests found in most electro-pneumatic organs, there are toe-holes that the pipes sit on and rackboard holes that support them upright. There are holes that serve as seats for primary and secondary valves. There are channels bored in the walls of the chests to allow the exhausting of pouches and there are exhaust ports in the magnets. All of those holes, except in the rackboards, have valves pressed against them to stop the flow of air. 

Let’s take that a step further. A fifty-stop organ has over 3,000 pipes. That’s 3,000 pipe valves. If that organ has seven manual windchests (two in the Great, two in the Swell, two in the Choir, and one in the Solo), that’s 427 primary valves, 427 secondary valves, and 427 magnet exhaust ports, in addition to the pipe valves. There’s one Pitman chest in the Pedal (Spitz Flute 8, Gedackt 8, Chorale Bass 4, Rauschpfeife III) with 32 of each. And there are three independent unit chests in the Pedal with 56 of each. Oh, wait. I forgot the stop actions, 50 times 3. And the expression motors, eight stages each, 16 times 3. And two tremolos . . . That’s 9,162 valves. Not counting the expressions and tremolos, every one of those valves can cause a cipher (when a stop action ciphers, you can’t turn the stop off). 

How many notes do you play on a Sunday morning? The Doxology has 32 four-part chords. That’s 128 notes. If you play it using 25 stops, that’s 3,200 notes, just for the Doxology! Are you playing that Widor Toccata for the postlude? There are 126 notes in the first measure. Using 25 stops? That’s 3,150 notes in the first measure! There are 61 measures. At 3,150 notes per measure, that’s 192,150 to finish the piece. (I haven’t counted the pedal part, and while the last three measures have big loud notes, there aren’t that many.) Using this math, you might be playing four or five hundred thousand notes in a busy service. And remember, in those Pitman chests, four valves operate for each note (magnet, primary, secondary, pipe valve), which means it takes 12,800 valve openings to play the Doxology, and 768,600 for the Widor. Let’s take a guess. With four hymns, some service music, an anthem or two, plus prelude and postlude, you might play 1,750,000 valves on a Sunday. (Lots more if your organ still has the original electro-pneumatic switching machines.) No ciphers today? Organ did pretty good. It’s a wonder it works at all.

Next time the personnel committee sits you down for a performance review, be sure to point out that you play 500,000 notes each Sunday morning.

 

Dust devils

Pull a couch away from the wall and you’ll find a herd of dust bunnies. Messy, but innocent enough, unless someone in your household is allergic to dust. But dust is a real enemy of the pipe organ. Fire is bad, water is bad, vandalism is bad, but dust is the evil lurker that attacks when you least expect it. A fleck of sawdust coming loose inside a windchest, left from when the organ was built, finds its way onto a pipe valve, and you’ve got a cipher.

Imagine this ordinary day in the life of a church. The organist is practicing, and the custodian is cleaning up in the basement. Airborne dust is sucked through the intake of the organ blower, and millions of potential cipher-causing particles waft through the wind ducts, through the reservoirs, and into the windchests, there to lurk until the last measure of the Processional March of the wedding of the daughter of the Chair of the Board of Trustees—whose family gave the money for the new organ. One pesky fleck hops onto the armature of the magnet of “D” (#39) of the Trompette-en-Chamade, and the last of Jeremiah’s notes continues into oblivion. (Ciphers never happen in the Aeoline when no one is around!)

I’m thinking about valves—how they work, what they do, what are their tolerances, and how many times they repeat to accomplish what we expect—because I was recently asked to provide an estimate for the cost of covering and protection of a large pipe organ during a massive renovation of the interior of a church building. There are organ cases on either side of the huge west window, and another big organ chamber in the front of the church, forming the corner between transept and chancel. There are lots of mixtures, and plenty of reeds—and with something like 3,500 pipes, a slew of valves.

The stained-glass west window will be removed for restoration, and the general contractor will construct a weather-tight box to close the hole. That’ll be quite a disturbance for the organ, with its Trompette-en-Chamade and mixture choruses. The plaster walls will be sanded and painted. The wooden ceiling with its complex system of trusses and beams will be cleaned and refinished. The entire nave, transept, and chancel will be filled with scaffolding, complete with a “full deck” 40 feet up, which will serve as a platform for all that work on the ceiling.

To properly protect a pipe organ against all that, removing the pipes, taping over the toeholes, and covering the windchests with hardboard and plastic is an important precaution. That means that all those little valves cannot be exposed to the dust and disturbance around the organ. To do that, you have to vacuum the chest surfaces, and organbuilders know how to do that without shoveling dust directly into the pipe holes.

The pipes that are enclosed in an expression chamber can be left in place if you disconnect the shutters, and seal the shutters closed with gaffer’s tape and plastic. Even, then, all the reeds should be removed, packed, and safely stored. 

The blower is the best way for foreign stuff to get inside the guts of the organ. It’s essential to prepare the organ blower for the building renovation. Wrap the blower’s air intake securely with plastic and heavy tape. Those 42-gallon “contractor” trash bags are great for this. And cut the power to the blower motor by closing circuit breakers, to be sure that it cannot be inadvertently started. Before you put the blower back into service, give the room a good cleaning, and allow a day or two for the dust to settle before you run the blower. It’s a simple precaution, but really important.

 

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It’s a lot of work to do all this to a big pipe organ. And it’s a lot more work to put it all back together and tune it. For the same amount of money you could buy a brand-new Steinway Concert Grand piano if it’s a big organ. But if you fail to do this, the future reliability of the organ may be seriously compromised. 

A bit of dust gets into a toehole, and winds up sitting on the note valve. Even if the valve is held open a tiny slit, the resulting trickle of air is enough to make a pipe whimper. A fleck of dust gets caught in the armature of a magnet, and the note won’t stop sounding. And I’m telling you, you wouldn’t believe how tiny, almost invisible a fleck is enough to do that. Lots of organ reed pipes, especially trumpets, are shaped like funnels, and they aggressively collect as much dust as they can. A little speck jolted off the inside of a reed resonator falls through the block and gets caught between the tongue and shallot. No speech.

To the hard-hat wearing, cigar-chewing general contractor, the organbuilder seems like a ninny, fussing about specks of dust. To the member of the vestry that must vote in favor of a huge expenditure to do with flecks of dust, the organbuilder seems like a carpetbagger, trying to sneak an expensive job out of thin air. To the organbuilder, the idea of all that activity, all that disturbance, all that dirt, all those vibrations, and all those workers with hammers, coffee cups, and sandwich wrappings swarming about the organ brings visions of worship made mockery, week after week, by an organ whose lungs are full of everything unholy.

Think about Sunday morning with Widor, Old Hundredth, and all the other festivities, think about valves opening and closing by the millions, and don’t tell me that “a little dust” isn’t going to hurt anything.

 

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This lecture is about caring for an organ during building renovation. If your church is planning to sand and refinish the floor, paint the walls and ceiling, replace the carpets (hope not!), or install a new heating and air conditioning system, be sure that the people making the decisions know about protecting the organ from the beginning. Your organ technician can help with advice, and any good organbuilder will be available and equipped to accomplish this important work for you. Any good-quality pipe organ of moderate size has a replacement value of hundreds of thousands of dollars. If yours is a three-manual organ with fifty stops, big enough to have a 32-foot stop, it’s likely worth over a million. The congregation that owns it depends on its reliable operation. A simple oversight can be the end of the organ’s reliability.

When there is no building renovation planned, we can carry these thoughts into everyday life. Institutional hygiene is essential for the reliability of the organ. Remember the custodian sweeping in the basement while you’re practicing? Think of the staff member looking for a place to stow a bunch of folding chairs, finding a handy closet behind the sanctuary. That pile of chairs on the bellows of the organ raises the wind pressure and wrecks the tuning. Or those Christmas decorations leaning up against those strange-looking machines—the roof timbers of the crèche may be leaning against a primary valve. You turn on the organ, draw a stop, and a note is playing continually. Organ technicians usually charge for their travel time. It could be a $300 service call for the right person to realize that a broomstick needs to be moved!

 

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When I hear a great organ playing, I often think of those valves in motion. The organist plays a pedal point on the 32 Bourdon while improvising during Communion, and in my mind’s eye, I can see a five-inch valve held open, with a hurricane of carefully regulated wind blowing into an organ pipe that weighs 800 pounds. A few minutes later, the organist gives the correct pause after the Benediction, swings into a blazing toccata, and thousands of valves open and close each second. Amazing, isn’t it?

Releathering and repairing pneumatic windchests, I’ve made countless valves myself. I know just what they look like and what they feel like. I like to dust them with talcum powder to keep them from sticking years down the road, and I picture what they smell like—the smell of baby powder mingling with the hot-glue pot. Hundreds of times during service calls or renovation jobs, I’ve opened windchests and seen just how little it takes to make a note malfunction. I’ve seen organ blowers located in the filthiest, stinkiest, rodent-filled, dirt-floored, moldy sumps. I’ve seen the everyday detritus of church life—hymnals, vestments, decorations, rummage-sale signs, and boxes of canned goods piled on organ walkboards and bellows, even dumped on windchests loaded with pipes. Can’t understand why the organ sounds so bad. 

Earlier this week, I visited an organ in which the static reservoir and blower were in a common storage space. A penciled sign was taped to the reservoir at chest height: “Please do not place anything on this unit. Sensitive parts of pipe organ. If you have any questions, see Norma.” When we say, “do not place anything,” how can there be questions?

To the untrained eye, the pipe organ may appear as a brute of a machine. But inside, it’s delicate and fragile. If “cleanliness is next to Godliness” in the wide world, cleanliness is the heart of reliability for the pipe organ. Institutional hygiene. Remember that.

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