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