Plastic Keytop Installation
By Craig Brougher
You can get a nice-looking one-piece keytop from Schaff Piano Supply Co., by the way. Commercial piano companies don't use one-piece tops because of their faster method of assembly and cutting. (I omitted the word "like" in my statement which, as a result, claimed that I thought they did.)
For the home rebuilder or professional restorer these are very fine quality keytops, too. They do not have that awful-looking quarter-round on the edges which make pianos look like cheap electronic organs. I put them on with acrylic cement after the key has been trimmed for the proper overall height with the new top, because cement dissolves and becomes one with the plastic, and so makes for a very strong bond. However, you have to be careful not to get any on the top of the key.
I do not use plastic glue because when I file the sides of the keys smooth, plastic glue is rolling off and clogging up the file. You can buy large quantities of key cement from APSCO. I then use the very small rubber band in two places for a clamp. Here, you have to be careful not to get any glue on it. And just to be sure, you should have an extra set around to rob spares from, just in case.
Sharp corners and edges are also 'verboten' on a key job. After precisely filing the top and the notch to the exact width of each key, the key will have been just "cleaned off" with the file, and you'll see fresh, new wood in place of the years of grime and black, impacted dirt from the fingers.
The next thing to do is to very _gently_ take the sharp corner off the keys with a notch in them, usually with carborundum paper, as well as the top edge of the key.
As you run the key through your hands, it should feel silky smooth with no sharp edges, look sharp and clean, and should also be true flat with the bottom and normal to the balance rail pin. My saw jig aligns the top of the key with four points, including the bottom and the balance rail hole for depth. On Steinway keys which have a platform on the balance seat, the jig has a button which raises the front of the key to level with its balance seat.
There is no special magic to replacing a set of keytops. The sharps are also glued with the same acrylic cement, by the way, and it seems to be the hollowness of the sharp which allows the glue to grip those edges all the way around. At least, I have never had one get knocked off in 30 years-- that I'm aware of.
Craig Brougher
[ I sure am enjoying this discussion, 'cause I'm a pianist and I
[ perform upon dozens of different pianos each year. A good ivory
[ keyboard is almost always pleasant and satisfying, but now and then
[ I play on plastic keytops which are superb! Thanks to all you techs
[ for your contributions and discussions of this topic. -- Robbie
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(Message sent Thu 30 Jan 1997, 15:10:50 GMT, from time zone GMT.) |
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