I went to my customer's house prepared to tune her piano. She had warned me that some notes weren't working, usually not a big deal. As soon as I opened the piano and looked inside, I could see the problem. There were shards of a yellowish white plastic all over the place. Oh no, plastic action parts!
To be fair, there's nothing wrong with plastic action parts if they're made correctly - the same can be said of wooden parts. This piano, a beautiful console made in 1957, had action parts made of PVC, and I'm sure the parts worked well for a time. Now the plastic had begun to disintegrate, and the parts would have to be replaced.
PVC, polyvinyl chloride, is usually referred to simply as vinyl. It is one of the most widely used plastics. It can be molded into things like pipes, it can be made into shiny cloth, and it can be bonded to fabric for use in upholstery, mimicking leather. The properties of vinyl chloride had been investigated as early as the late 19th century, but it wasn't until the 1930's that a commercially viable plastic was developed. PVC is quite rigid and brittle, and requires the addition of various plasticizers and stabilizers. Vinyl combined with cellulose acetate (another plastic) as a plasticizer is what replaced lacquer for making phonograph records, starting in the 40's. Vinyl without plasticizers is what is molded into rigid shapes, like pipes for plumbing, and siding and flooring for houses.
Rigid PVC should have been perfect for replacing wooden parts in a piano action. The plastic parts were molded in the same shape as the wooden ones, and installed the same way. The most common plastic parts were flanges, which are the hinged ends of many action parts and are attached with screws to various rails. In some actions, backchecks, jacks, and damper levers were also made of PVC. The only parts that were not made of plastic were the parts that are glued to each other. PVC parts can be bonded together (using the solvent methylethylketone, or MEK, often called PVC glue), but I guess this was not viable for the action manufacturers. I did see a Lindner piano, made in Ireland, probably in the 60's, whose action was entirely of plastic. Even the keys were plastic, made of sheets of PVC glued into long hollow rectangles.
The problem with PVC, as with many other plastics, is outgassing. The various additives that give vinyl its different characteristics slowly evaporate out of the plastic. Over time, some plastic becomes more brittle, or shrinks, or becomes discolored, or, in the case of PVC, spontaneously disintegrates. The technology behind the additives is almost more important than the technology behind the plastic resin itself. When PVC was used for piano actions, the technology for stabilizing rigid PVC must have been in its infancy. It was not foreseen that the outgassing would proceed so quickly, that the actions would start to fall apart in a couple of decades. Modern PVC could be used with no problem, but now the piano industry won't go anywhere near it, and modern plastic action parts are made of other plastics.
The solution is simple, but costly. The parts must be replaced. PVC spinet elbows are replaced with acrylic ones, but other parts are replaced with wooden ones. The parts are readily available because of the demand. Sometimes not all of the PVC is falling apart, so apparently the outgassing varies from batch to batch. For instance, in the case of the console I'm working on, the jacks and backchecks are completely shot, they crumble at a touch, but the hammer flanges and damper levers are fine. They're not the least bit brittle. I won't replace them for now, but I have warned the owner about the possible need for replacement in the future.
There has been one other use of vinyl in pianos. Some of the more crazy and delightful console and spinet case designs from the 40's and 50's used vinyl upholstery fabric in addition to the more traditional wooden veneer. It's found on the sides and top, and Wurlitzer was the main culprit. The vinyl is usually embossed with the classic leather grain, and my favorite example used a white-with-brown-spots cowhide pattern.
Vinyl imitation leather has also been used to replace the leather on the ends of bridle straps, the straps that connect upright hammers to the wippens. Over time, the leather disintegrates (not to mention the strap itself), but the vinyl holds up for much longer. The only disadvantage is that it stiffens up over time and can rattle against the bridle wire. It also becomes harder to remove from the wire. I'll have more to say about the use of artificial leather and suede in pianos in a later post.
Related website:
The Plastics Historical Society
Showing posts with label Parts and Materials. Show all posts
Showing posts with label Parts and Materials. Show all posts
Monday, May 25, 2009
Sunday, May 24, 2009
The Plastic Piano - Introduction
The piano manufacturing industry is quite progressive, eager to embrace any new material or manufacturing process. The goal is usually to save money, to keep the price of a new piano down, but sometimes an innovation can add value to a piano, improve it in some way that can be reflected in a higher price or a more competitive product.
Plastic has always been one of those new materials, ever since the industry started using celluloid in the 1870's. The chemistry behind various plastics was not well understood then, and innovation relied on experimentation, sometimes with terrible results. There were three prominent plastics disasters in piano manufacturing history. The first was with PVC, used in the 1940's and 50's to make action parts. Molded PVC parts were successful at first, but as the plastic aged, it tended to spontaneously disintegrate. This effect would take several decades to manifest, so that left a lot of time to build plenty of pianos with PVC action parts, all falling apart now.
The second was with Steinway's Teflon action center bushings. These were tiny inserts made of Teflon, hundreds per piano, that Steinway used in the 70's. They worked well at first, but after a few years they became quite noisy and needed replacing. Steinway tried again with a different size insert, and they did work better, but Steinway eventually abandoned the effort and went back to felt bushings.
The third was less disastrous, but still annoying, and it involved Yamaha's Ivorite, a plastic for keytops developed in the 80's. This plastic is porous, and thus does not feel as slick and slippery as other plastic keytops. It soon became evident that it was a bit too porous. As the plastic soaked up finger oils, it stained in a way that looked, frankly, disgusting. Yamaha reformulated the plastic, and offered to replace all the unsightly keyboards. Now the Ivorite works fine.
These negative experiences with plastic has made the industry wary of introducing more plastic into pianos. Pianos are sold, after all, on their 19th century charm, and nothing screams "modern" (not to mention "cheap") like plastic. The word itself is avoided like the plague, and replaced with phrases like "thermoset composite material," or trademarks like "Ivorite." Often plastic is introduced in small ways, in parts of the piano not visible, or crucial to its function as an instrument. When plastic is obviously employed in a significant way, a whole public-relations blitz is rolled out to carefully explain how the new plastic parts are a huge improvement over the old parts, whether or not that is true. When Kawai used its first plastic action part in the 90's, a plastic jack, I was asked by the local dealer to sign a statement in support that would be used for advertising. I was more than happy to help until I read the statement. It was asking me to agree that the new plastic part was superior to the old wooden part, which was ridiculous, and not true in this case. I refused, much to the dealer's anger.
Nothing has changed the piano in the 20th century as much as plastic has, and I am going to post a number of articles about the plastics used in pianos, all under this heading of The Plastic Piano. I'll keep the series as a permanent link in the sidebar. Glues and wood finishes are forms of plastic, and I will include them.
Modern plastics, and modern chemistry, is a whole different world from eighty years ago, and I am glad to report that current uses of plastic are much better engineered. Some of these parts are not only cheaper, but they really are an improvement over the old parts, taking advantage of the qualities of different plastics as materials. Manufacturers are beginning to be less furtive, less scared of the older disasters. Having tiptoed through the plastics revolution of the late 20th century, maybe the industry can enter the 21st more boldly.
Related website:
The Plastics Historical Society
Plastic has always been one of those new materials, ever since the industry started using celluloid in the 1870's. The chemistry behind various plastics was not well understood then, and innovation relied on experimentation, sometimes with terrible results. There were three prominent plastics disasters in piano manufacturing history. The first was with PVC, used in the 1940's and 50's to make action parts. Molded PVC parts were successful at first, but as the plastic aged, it tended to spontaneously disintegrate. This effect would take several decades to manifest, so that left a lot of time to build plenty of pianos with PVC action parts, all falling apart now.
The second was with Steinway's Teflon action center bushings. These were tiny inserts made of Teflon, hundreds per piano, that Steinway used in the 70's. They worked well at first, but after a few years they became quite noisy and needed replacing. Steinway tried again with a different size insert, and they did work better, but Steinway eventually abandoned the effort and went back to felt bushings.
The third was less disastrous, but still annoying, and it involved Yamaha's Ivorite, a plastic for keytops developed in the 80's. This plastic is porous, and thus does not feel as slick and slippery as other plastic keytops. It soon became evident that it was a bit too porous. As the plastic soaked up finger oils, it stained in a way that looked, frankly, disgusting. Yamaha reformulated the plastic, and offered to replace all the unsightly keyboards. Now the Ivorite works fine.
These negative experiences with plastic has made the industry wary of introducing more plastic into pianos. Pianos are sold, after all, on their 19th century charm, and nothing screams "modern" (not to mention "cheap") like plastic. The word itself is avoided like the plague, and replaced with phrases like "thermoset composite material," or trademarks like "Ivorite." Often plastic is introduced in small ways, in parts of the piano not visible, or crucial to its function as an instrument. When plastic is obviously employed in a significant way, a whole public-relations blitz is rolled out to carefully explain how the new plastic parts are a huge improvement over the old parts, whether or not that is true. When Kawai used its first plastic action part in the 90's, a plastic jack, I was asked by the local dealer to sign a statement in support that would be used for advertising. I was more than happy to help until I read the statement. It was asking me to agree that the new plastic part was superior to the old wooden part, which was ridiculous, and not true in this case. I refused, much to the dealer's anger.
Nothing has changed the piano in the 20th century as much as plastic has, and I am going to post a number of articles about the plastics used in pianos, all under this heading of The Plastic Piano. I'll keep the series as a permanent link in the sidebar. Glues and wood finishes are forms of plastic, and I will include them.
Modern plastics, and modern chemistry, is a whole different world from eighty years ago, and I am glad to report that current uses of plastic are much better engineered. Some of these parts are not only cheaper, but they really are an improvement over the old parts, taking advantage of the qualities of different plastics as materials. Manufacturers are beginning to be less furtive, less scared of the older disasters. Having tiptoed through the plastics revolution of the late 20th century, maybe the industry can enter the 21st more boldly.
Related website:
The Plastics Historical Society
Tuesday, April 21, 2009
Staying in Tune
Why does a piano go out of tune? Here's one short answer: a piano holds strings that are under tension, and any material under tension tends to react in a way to diminish that tension.
This is not to say that the strings are the only material in a piano reacting to tension. Certainly when the strings are new they go through a period of "stretching out," but modern string manufacturing has ensured that this stretching comes almost to a halt within a couple of years. The tension of the strings, however, is brought to bear on many different parts of the piano, and it is the reaction of all these parts to the tension that contributes to the instability of a tuning.
String tension is possible only if the strings are secured at each end, so these end points carry the brunt of the string tension. One end is the hitchpin, which is usually a small steel pin driven into the cast-iron plate. This end is pretty stable. The other end is the tuning pin, which is a large steel pin driven into the wooden pinblock. This end is much less stable because the wood reacts rather strongly to the tension. The tension is enough to slowly pull the pin right out of the wood, a phenomenon seen on many smaller uprights. Before that point is reached, though, the hole that the tuning pin sits in can become sufficiently distorted and enlarged that the pin can rotate, either slowly or suddenly, releasing the string tension.
The string also passes under, over, and around various bearing points, all of which react to the tension. An important bearing point is the wooden bridge, which miraculously carries tension in three directions: each string is bearing downward on the bridge, bearing to the right against one bridge pin, and bearing to the left against another bridge pin. Bridges are known to crack, split, and otherwise fall apart as a result. But even if a bridge doesn't fall apart, the pins still creep and the wood compresses, releasing some of the tension.
The bridge, in turn, bears down upon the soundboard, a giant raft of wood that must support all this tension. This brings us to another short answer to why pianos go out of tune: a piano is made mostly of wood, and wood expands and contracts with changes in humidity. As the humidity changes, and the soundboard absorbs and releases moisture, the board flexes up and down, and the bridge and strings with it. The bridge also rocks and tilts back and forth, and indeed all the wooden parts including the pinblock expand and contract. All this movement changes the tension of the strings.
The soundboard is often constructed under its own tension, pushing upward against the bridge to forestall its eventual collapse. When the humidity is high and the wood expands, it crushes itself against its joints and constraints, and then, when dry, it shrinks and cracks. The glue lets go. It is no surprise that almost all pianos have cracked soundboards.
Even the metal bearing points give way to the string tension. If you examine the agraffes and pressure bars and duplex scales and aliquots and capos, you'll see where the strings have slowly and steadily pressed grooves into the brass and steel and iron.
So it is a wonder that a piano stays in tune at all. Then comes the tuner, and another short answer to why pianos go out of tune: the tuner has to temporarily destabilize the string to add or subtract tension, and may not be successful in restoring the string's stability. The instability introduced by the tuner comes in two forms. Theoretically, the tuning pin simply sits in its hole in the pinblock, but in reality the tuning pin floats in a bed of highly compressed wood, with the greatest compression where the string pulls against the pin. The pin, the wood, and the string have arrived at a temporary stasis, which the tuner disrupts when he or she turns the pin. The tuner must then try to set the pin back in a position where it won't wander under the new tension. I can tell you that this is the trickiest part of tuning.
The second instability comes because of all the string bearing points. Theoretically, any change made to the string's tension applies evenly to the entire string, but in reality the friction of the string against its bearings prevents the even distribution of the tension. The tuner must ensure that there is no extra tension hidden in some section of the string that will suddenly release itself in a glorious detuning as soon as the string is hit with the hammer. This is why tuners strike the notes so vigorously when they tune, to work out the uneven distribution of tension. Some instability is inevitably left behind, to be eventually worked out to the player's dismay.
This is not to say that the strings are the only material in a piano reacting to tension. Certainly when the strings are new they go through a period of "stretching out," but modern string manufacturing has ensured that this stretching comes almost to a halt within a couple of years. The tension of the strings, however, is brought to bear on many different parts of the piano, and it is the reaction of all these parts to the tension that contributes to the instability of a tuning.
String tension is possible only if the strings are secured at each end, so these end points carry the brunt of the string tension. One end is the hitchpin, which is usually a small steel pin driven into the cast-iron plate. This end is pretty stable. The other end is the tuning pin, which is a large steel pin driven into the wooden pinblock. This end is much less stable because the wood reacts rather strongly to the tension. The tension is enough to slowly pull the pin right out of the wood, a phenomenon seen on many smaller uprights. Before that point is reached, though, the hole that the tuning pin sits in can become sufficiently distorted and enlarged that the pin can rotate, either slowly or suddenly, releasing the string tension.
The string also passes under, over, and around various bearing points, all of which react to the tension. An important bearing point is the wooden bridge, which miraculously carries tension in three directions: each string is bearing downward on the bridge, bearing to the right against one bridge pin, and bearing to the left against another bridge pin. Bridges are known to crack, split, and otherwise fall apart as a result. But even if a bridge doesn't fall apart, the pins still creep and the wood compresses, releasing some of the tension.
The bridge, in turn, bears down upon the soundboard, a giant raft of wood that must support all this tension. This brings us to another short answer to why pianos go out of tune: a piano is made mostly of wood, and wood expands and contracts with changes in humidity. As the humidity changes, and the soundboard absorbs and releases moisture, the board flexes up and down, and the bridge and strings with it. The bridge also rocks and tilts back and forth, and indeed all the wooden parts including the pinblock expand and contract. All this movement changes the tension of the strings.
The soundboard is often constructed under its own tension, pushing upward against the bridge to forestall its eventual collapse. When the humidity is high and the wood expands, it crushes itself against its joints and constraints, and then, when dry, it shrinks and cracks. The glue lets go. It is no surprise that almost all pianos have cracked soundboards.
Even the metal bearing points give way to the string tension. If you examine the agraffes and pressure bars and duplex scales and aliquots and capos, you'll see where the strings have slowly and steadily pressed grooves into the brass and steel and iron.
So it is a wonder that a piano stays in tune at all. Then comes the tuner, and another short answer to why pianos go out of tune: the tuner has to temporarily destabilize the string to add or subtract tension, and may not be successful in restoring the string's stability. The instability introduced by the tuner comes in two forms. Theoretically, the tuning pin simply sits in its hole in the pinblock, but in reality the tuning pin floats in a bed of highly compressed wood, with the greatest compression where the string pulls against the pin. The pin, the wood, and the string have arrived at a temporary stasis, which the tuner disrupts when he or she turns the pin. The tuner must then try to set the pin back in a position where it won't wander under the new tension. I can tell you that this is the trickiest part of tuning.
The second instability comes because of all the string bearing points. Theoretically, any change made to the string's tension applies evenly to the entire string, but in reality the friction of the string against its bearings prevents the even distribution of the tension. The tuner must ensure that there is no extra tension hidden in some section of the string that will suddenly release itself in a glorious detuning as soon as the string is hit with the hammer. This is why tuners strike the notes so vigorously when they tune, to work out the uneven distribution of tension. Some instability is inevitably left behind, to be eventually worked out to the player's dismay.
Wednesday, January 28, 2009
Creativity or Incompetence?
This is the first part of a two-part post. The second part is here.
The line between creative problem-solving and hack-work is blurry. A solution acceptable to one may be unacceptable to another. There is room for disagreement, and circumstances are never so clear as to make the best solution obvious. Budgets need to be adhered to, piano usage differs, pianos vary in quality, time is an ingredient. The main difference between hack-work and creative problem-solving is in the use of judgement. Was a repair made hastily with little thinking about the full effects? Was a repair executed poorly for lack of insight about materials or mechanisms? Were money and time not spent out of mere stinginess?
When I was working in a rebuilding shop, the movers one day rolled in a small upright which we promptly took apart and examined. One look at the bass bridge, and we all began laughing and pointing. Some poor soul had attempted to repair the bridge with hilariously disastrous results. Later, one of the crew admitted to having done the work years before, and insisted that it had been a creative solution. It sure looked like hack-work to the rest of us, though.
What this technician had encountered was a bass bridge that had split along the pin line - a common occurrence. Apparently many of the bridge pins had actually fallen out, the rest had shifted well out of place, and the unmoored bass strings were buzzing like crazy. Some people might have said forget it, the piano is junk - it was of mediocre quality to begin with, and the split bridge could have been indicative of many other problems throughout the piano.
The "proper" way to fix the bridge would have been to move the piano to a shop, flip it on its back, remove the trap and pedalwork, loosen the bass strings and move them aside, remove the bass bridge and make and install a replacement. But the sort of owners who have a piano like this are usually the sort who cannot afford such a procedure. Is there a creative solution between these extremes?
Our beleaguered technician tried this: he would fill the crack with epoxy, and then drive in new pins. It wasn't the best idea, and executed poorly it could be a disaster, and without the proper setup it would be cumbersome work, but that's what he did. And he ran into difficulties.
Epoxy does have gap-filling ability, but there is a limit. A narrow crack can be sealed, but this was a canyon he was trying to fill. I'm sure he discovered that you can't draw a cracked bridge back together by clamping, either. And a bridge pin driven into epoxy is not going to hold the way it does in wood. At best this would be an impermanent repair that would perhaps alter the scaling of the bass section and not allow the bass strings to correctly sit on the bridge. But it might eliminate the buzzing and allow for tuning, however temporary, and at little cost. It's potentially a creative solution for the conditions, even given the limitations.
Here's where it all went wrong: the technician had no extra bridge pins, and he hadn't given himself the time to order them and wait for the shipment. He tried making his own by cutting the ends off of small common nails. Even this is creative and not entirely incorrect. A bridge pin does look like the end of a nail. If you did it correctly and carefully you could make a batch of bridge pins this way. But the technician was running out of time, and time is money.
Bridge pins might look like small nails, but they are not installed the way nails are. They are not driven into the bridge, and if you try it you'll see why. Holes of the proper diameter and angle must be drilled first, and the pins are then tapped in. There should be enough friction to hold the pins securely. Our intrepid technician overlooked this detail, and with bridge pins/nails in hand, proceeded to hammer away. The pins ended up angled every which way, some mashed and bent, and not exactly lined up properly. The epoxy set, and for good or ill our man was done.
To his credit, he had eliminated the buzzing, and the piano could be tuned well enough for his customer, who was happy to have not been billed a lot of money for the work. Over time, the epoxy had held, though I'm sure the pins had drifted, and maybe the buzzing had started to come back. I'm sure it was more work and hassle for the technician than it was worth, and ultimately embarrassing.
Next: my turn.
The line between creative problem-solving and hack-work is blurry. A solution acceptable to one may be unacceptable to another. There is room for disagreement, and circumstances are never so clear as to make the best solution obvious. Budgets need to be adhered to, piano usage differs, pianos vary in quality, time is an ingredient. The main difference between hack-work and creative problem-solving is in the use of judgement. Was a repair made hastily with little thinking about the full effects? Was a repair executed poorly for lack of insight about materials or mechanisms? Were money and time not spent out of mere stinginess?
When I was working in a rebuilding shop, the movers one day rolled in a small upright which we promptly took apart and examined. One look at the bass bridge, and we all began laughing and pointing. Some poor soul had attempted to repair the bridge with hilariously disastrous results. Later, one of the crew admitted to having done the work years before, and insisted that it had been a creative solution. It sure looked like hack-work to the rest of us, though.
What this technician had encountered was a bass bridge that had split along the pin line - a common occurrence. Apparently many of the bridge pins had actually fallen out, the rest had shifted well out of place, and the unmoored bass strings were buzzing like crazy. Some people might have said forget it, the piano is junk - it was of mediocre quality to begin with, and the split bridge could have been indicative of many other problems throughout the piano.
The "proper" way to fix the bridge would have been to move the piano to a shop, flip it on its back, remove the trap and pedalwork, loosen the bass strings and move them aside, remove the bass bridge and make and install a replacement. But the sort of owners who have a piano like this are usually the sort who cannot afford such a procedure. Is there a creative solution between these extremes?
Our beleaguered technician tried this: he would fill the crack with epoxy, and then drive in new pins. It wasn't the best idea, and executed poorly it could be a disaster, and without the proper setup it would be cumbersome work, but that's what he did. And he ran into difficulties.
Epoxy does have gap-filling ability, but there is a limit. A narrow crack can be sealed, but this was a canyon he was trying to fill. I'm sure he discovered that you can't draw a cracked bridge back together by clamping, either. And a bridge pin driven into epoxy is not going to hold the way it does in wood. At best this would be an impermanent repair that would perhaps alter the scaling of the bass section and not allow the bass strings to correctly sit on the bridge. But it might eliminate the buzzing and allow for tuning, however temporary, and at little cost. It's potentially a creative solution for the conditions, even given the limitations.
Here's where it all went wrong: the technician had no extra bridge pins, and he hadn't given himself the time to order them and wait for the shipment. He tried making his own by cutting the ends off of small common nails. Even this is creative and not entirely incorrect. A bridge pin does look like the end of a nail. If you did it correctly and carefully you could make a batch of bridge pins this way. But the technician was running out of time, and time is money.
Bridge pins might look like small nails, but they are not installed the way nails are. They are not driven into the bridge, and if you try it you'll see why. Holes of the proper diameter and angle must be drilled first, and the pins are then tapped in. There should be enough friction to hold the pins securely. Our intrepid technician overlooked this detail, and with bridge pins/nails in hand, proceeded to hammer away. The pins ended up angled every which way, some mashed and bent, and not exactly lined up properly. The epoxy set, and for good or ill our man was done.
To his credit, he had eliminated the buzzing, and the piano could be tuned well enough for his customer, who was happy to have not been billed a lot of money for the work. Over time, the epoxy had held, though I'm sure the pins had drifted, and maybe the buzzing had started to come back. I'm sure it was more work and hassle for the technician than it was worth, and ultimately embarrassing.
Next: my turn.
Sunday, January 11, 2009
Nice Piece of Trapwork
I found a design flaw in a Boston grand. Boston is the brand designed by Steinway and built by the Kawai factory in Japan. They're really beautiful pianos.
The notes were making a clanking sound, and I guessed the problem right away. I could feel it - the dampers were jumping up too high at the end of the keystroke, and instead of being stopped by the stop rail, they were hitting the metal sostenuto rail.
So the damper stop rail was positioned too high. That's easy enough to fix, but I had to find out first why the rail was out of position. The usual culprit is that the damper pedal isn't being properly stopped. As a result, every time the pedal is depressed, the damper tray pushes all the dampers hard into the stop rail. Over time this succeeds in pushing the damper stop rail up out of the way. Hence, clanking.
The usual way to stop the damper pedal is by stopping the damper trap lever, which the pedal moves by pushing up on the pedal rod. I got under the piano and took a look. The stop consisted of a capstan screwed into the case underside. Whenever the pedal was depressed, a piece of felt glued to the top of the lever contacted the capstan, stopping the lever. The capstan made it adjustable, the felt reduced noise. The felt, though, was soft - it was the kind of woven felt used for the hammer rail in an upright. The capstan was quite small, and it had driven a divot into the soft felt, rendering the stop useless.
I thought of simply adjusting the capstan, but I would have had to adjust it quite a bit, which is not a lot of fun to do lying on one's back. The possibilities also existed that the capstan might not have been long enough to fill the gap, and that the felt was now too thin at the contact point to provide any padding. I also thought of simply adding more felt, but the misshapen felt really needed replacing, so I removed the trap lever from the piano.
If there's anyplace where a manufacturer is going to try to save money, it's the trapwork. But this was the most beautifully made trap lever I had ever seen. The coil spring sat in a lovely felt-lined cup, and had a piece of felt carefully woven through it to avoid creaking. The pitman sat on a buckskin/felt cushion inlay, and there was a generous piece of hard leather where the pedal rod made contact. There even was a piece of buckskin wrapped across the bottom and up the side of the lever to protect it from contact with the guide hook. The only flaw was the soft stop felt. What was needed was a chunk of hard felt, like the kind used for hammer heads, and that's what I installed.
The design error was that the felt was too soft for the capstan. If the capstan had been much larger in diameter, and therefore exerting less pressure (pressure = force/surface area), it might have worked. I was actually tempted to remove the capstan and install the traditional stop: a piece of wood glued to the underside of the case, with the hard felt attached to it, and no felt on the lever itself. This works well, and eliminates the possibility of a divot, but it's not as easy to adjust. So I'll have to keep an eye on my new stop felt; this piano gets a lot of use.
The notes were making a clanking sound, and I guessed the problem right away. I could feel it - the dampers were jumping up too high at the end of the keystroke, and instead of being stopped by the stop rail, they were hitting the metal sostenuto rail.
So the damper stop rail was positioned too high. That's easy enough to fix, but I had to find out first why the rail was out of position. The usual culprit is that the damper pedal isn't being properly stopped. As a result, every time the pedal is depressed, the damper tray pushes all the dampers hard into the stop rail. Over time this succeeds in pushing the damper stop rail up out of the way. Hence, clanking.
The usual way to stop the damper pedal is by stopping the damper trap lever, which the pedal moves by pushing up on the pedal rod. I got under the piano and took a look. The stop consisted of a capstan screwed into the case underside. Whenever the pedal was depressed, a piece of felt glued to the top of the lever contacted the capstan, stopping the lever. The capstan made it adjustable, the felt reduced noise. The felt, though, was soft - it was the kind of woven felt used for the hammer rail in an upright. The capstan was quite small, and it had driven a divot into the soft felt, rendering the stop useless.
I thought of simply adjusting the capstan, but I would have had to adjust it quite a bit, which is not a lot of fun to do lying on one's back. The possibilities also existed that the capstan might not have been long enough to fill the gap, and that the felt was now too thin at the contact point to provide any padding. I also thought of simply adding more felt, but the misshapen felt really needed replacing, so I removed the trap lever from the piano.
If there's anyplace where a manufacturer is going to try to save money, it's the trapwork. But this was the most beautifully made trap lever I had ever seen. The coil spring sat in a lovely felt-lined cup, and had a piece of felt carefully woven through it to avoid creaking. The pitman sat on a buckskin/felt cushion inlay, and there was a generous piece of hard leather where the pedal rod made contact. There even was a piece of buckskin wrapped across the bottom and up the side of the lever to protect it from contact with the guide hook. The only flaw was the soft stop felt. What was needed was a chunk of hard felt, like the kind used for hammer heads, and that's what I installed.
The design error was that the felt was too soft for the capstan. If the capstan had been much larger in diameter, and therefore exerting less pressure (pressure = force/surface area), it might have worked. I was actually tempted to remove the capstan and install the traditional stop: a piece of wood glued to the underside of the case, with the hard felt attached to it, and no felt on the lever itself. This works well, and eliminates the possibility of a divot, but it's not as easy to adjust. So I'll have to keep an eye on my new stop felt; this piano gets a lot of use.
Wednesday, December 17, 2008
The Only Thing They've Done Wrong
The dampers in a piano run from the first note up to about the 68th note, the E two octaves above middle C, which is called E6. After that, there really is no need for dampers because the strings don't ring out for very long. Some pianos run dampers 5 or 6 notes above E6, but most piano manufacturers avoid the extra cost and stop at E6 (or try to cut it a bit short one or two notes).
Most of the time you don't notice where the dampers leave off, but a sensitive player will always notice. Sometimes it can be annoying, because the notes just after the last damper can't really be played staccato, and the transition from damper to no-damper is abrupt both for the hand and for the ear.
In an attempt to ameliorate this abrupt transition, Yamaha uses a partial damper felt on its last damper, E6. The idea is that D#6 damps fully, E6 damps partially, and F6 damps not at all - voilà, a smooth transition! Except not really. It's a nice idea, and probably a nice marketing point, but listen carefully to the transition, and you might hear what I'm hearing as the notes die out.
The sound in a piano comes from hammers hitting strings. As soon as a string is struck, it vibrates and transmits most of its energy ultimately to the soundboard, thence to the air as sound waves. As the string gives up its energy, the volume of the sound decreases, a process called decay. Decay begins immediately after the string is struck, and is rapid at first, but then the decay rate drops quickly. In a good piano, the decay rate slows significantly; the string can ring out, at a moderate yet still decreasing volume, for a long time.
Here's my beef with Yamaha's partial damper. D#6, E6, and F6 all have a similar decay, as one would hope. D#6 can also have its sound damped, and F6 cannot. But when you damp E6, only two of the three strings are damped. The third string rings out, but it decays at a significantly different rate than F6. Instead of hearing a smooth transition, I actually hear two different transitions; the one from D#6 to E6, and the one from E6 to F6. Call me sensitive, but it drives me crazy; I'd rather have the one abrupt transition.
The reason the decay is different, by the way, is because a single string transfers energy to the soundboard differently than three strings vibrating in phase. Of course, the difference is greater in the early part of the decay. Towards the end of the decay, the difference is negligible to none. But if you're relying on the damper to do its job, you usually want to apply it in the early part of the decay.
Well, if this is all Yamaha has done wrong, they're doing OK. But I've noticed a growing number of manufacturers mimicking Yamaha's partial damper, and it can't be because it works so well.
Most of the time you don't notice where the dampers leave off, but a sensitive player will always notice. Sometimes it can be annoying, because the notes just after the last damper can't really be played staccato, and the transition from damper to no-damper is abrupt both for the hand and for the ear.
In an attempt to ameliorate this abrupt transition, Yamaha uses a partial damper felt on its last damper, E6. The idea is that D#6 damps fully, E6 damps partially, and F6 damps not at all - voilà, a smooth transition! Except not really. It's a nice idea, and probably a nice marketing point, but listen carefully to the transition, and you might hear what I'm hearing as the notes die out.
The sound in a piano comes from hammers hitting strings. As soon as a string is struck, it vibrates and transmits most of its energy ultimately to the soundboard, thence to the air as sound waves. As the string gives up its energy, the volume of the sound decreases, a process called decay. Decay begins immediately after the string is struck, and is rapid at first, but then the decay rate drops quickly. In a good piano, the decay rate slows significantly; the string can ring out, at a moderate yet still decreasing volume, for a long time.
Here's my beef with Yamaha's partial damper. D#6, E6, and F6 all have a similar decay, as one would hope. D#6 can also have its sound damped, and F6 cannot. But when you damp E6, only two of the three strings are damped. The third string rings out, but it decays at a significantly different rate than F6. Instead of hearing a smooth transition, I actually hear two different transitions; the one from D#6 to E6, and the one from E6 to F6. Call me sensitive, but it drives me crazy; I'd rather have the one abrupt transition.
The reason the decay is different, by the way, is because a single string transfers energy to the soundboard differently than three strings vibrating in phase. Of course, the difference is greater in the early part of the decay. Towards the end of the decay, the difference is negligible to none. But if you're relying on the damper to do its job, you usually want to apply it in the early part of the decay.
Well, if this is all Yamaha has done wrong, they're doing OK. But I've noticed a growing number of manufacturers mimicking Yamaha's partial damper, and it can't be because it works so well.
Sunday, December 14, 2008
Alloy Electric
Look at what my pal Chris Warren is up to with old uprights. I have to admit, I was the one who told him how to take a piano apart.
He does this to build an instrument he calls the feedback piano. It consists of the soundboard, strings, and plate of a piano still attached to the case. It's rigged with electronics to take input from the soundboard and also to apply vibration to the soundboard, creating a sustained and controllable feedback when sound is introduced. Check out the video.
Related website:
Alloy Electric
Brittle Strings
I recently tuned a small Ampico grand, from the late 30's or early 40's I would guess. It had those brittle strings which throw off a lot of high frequencies, making it difficult to tune. I've noticed this before on old Ampico grands, and old Sohmer grands, too. Jewetts are famous for this problem - my heart sinks when I open up a Jewett upright and see all those broken strings in the extreme treble.
The high frequencies tend to cause me to tune the strings a little sharp. Then I struggle to get them back down, a struggle exacerbated by the inevitable rust on the strings and corrosion at the agraffes. When I was done, though, the tuning was fine, but the piano sounded a little harpsichord-ish, except for the tubby bass, all of which is typical.
I've tuned old Chickerings that were older than a century, and I've not had quite the same trouble, even though the strings were plenty brittle. The difference seems to be that on the Chickering, the string tension is much lower. I've also tuned pianos as old as the Ampico but whose strings were not nearly as brittle. The strings that tend toward premature brittleness must be of a different composition. Even the rust on them looks a little different.
Increased brittleness in strings is a natural consequence of age. The strings, which are under constant tension for decades, actually change their molecular structure over time. The atoms creep and shift, relieving some of the stress. This is the string "stretching out," something it does for its whole existence. The string becomes less springy, more brittle, more liable to break, more likely to throw off false beats. The fundamental frequency weakens, making the string sound tinny, and the string's overtones probably become more inharmonic because of the increased stiffness. I think that's what fools my ear when I tune.
A few things to bear in mind when tuning a piano like the little Ampico. Be very careful about raising pitch - you don't need to overshoot A440 much because there's not much stretch left in the strings, and I don't recommend raising more than 100 cents without letting the strings rest. Expect false beats - don't mess too much with unisons, it'll be easier to touch them up later after the strings have rested a little. Finally, you'll notice that the brittleness increases as you move up the piano, perhaps because the strings are thinnner. That's why in a Jewett you'll see all those broken and replaced strings up there.
Related websites:
There does seem to be controversy and confusion about exactly what happens to piano wire under tension over time. There are several ways that strings "stretch out," but the mechanism I'm referring to is creep embrittlement.
See Wikipedia on:
Deformation of materials
Material strength and toughness (including steel)
Dislocation within crystal structures
The high frequencies tend to cause me to tune the strings a little sharp. Then I struggle to get them back down, a struggle exacerbated by the inevitable rust on the strings and corrosion at the agraffes. When I was done, though, the tuning was fine, but the piano sounded a little harpsichord-ish, except for the tubby bass, all of which is typical.
I've tuned old Chickerings that were older than a century, and I've not had quite the same trouble, even though the strings were plenty brittle. The difference seems to be that on the Chickering, the string tension is much lower. I've also tuned pianos as old as the Ampico but whose strings were not nearly as brittle. The strings that tend toward premature brittleness must be of a different composition. Even the rust on them looks a little different.
Increased brittleness in strings is a natural consequence of age. The strings, which are under constant tension for decades, actually change their molecular structure over time. The atoms creep and shift, relieving some of the stress. This is the string "stretching out," something it does for its whole existence. The string becomes less springy, more brittle, more liable to break, more likely to throw off false beats. The fundamental frequency weakens, making the string sound tinny, and the string's overtones probably become more inharmonic because of the increased stiffness. I think that's what fools my ear when I tune.
A few things to bear in mind when tuning a piano like the little Ampico. Be very careful about raising pitch - you don't need to overshoot A440 much because there's not much stretch left in the strings, and I don't recommend raising more than 100 cents without letting the strings rest. Expect false beats - don't mess too much with unisons, it'll be easier to touch them up later after the strings have rested a little. Finally, you'll notice that the brittleness increases as you move up the piano, perhaps because the strings are thinnner. That's why in a Jewett you'll see all those broken and replaced strings up there.
Related websites:
There does seem to be controversy and confusion about exactly what happens to piano wire under tension over time. There are several ways that strings "stretch out," but the mechanism I'm referring to is creep embrittlement.
See Wikipedia on:
Deformation of materials
Material strength and toughness (including steel)
Dislocation within crystal structures
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