Piano Tuning | Page 6

The bottom of the hole in the key fits closely around

the balance pin; at the top, it is the shape of a mortise, parallel with the
key, which allows the key to move only in the direction intended. The
mortise in the wooden cap on top of the key at this point is lined with
bushing cloth which holds the key in position laterally, and prevents
looseness and rattling, yet allows the key to move easily.
L, is the lead put in this portion of the key to balance it, and to insure
uniformity of "touch," and quick and certain return of key to its rest
position. As there is more or less difference in the length of keys, and
also in the weight of the hammers operated by them, some keys are
leaded much more heavily than others. In some cases the lead is
inserted in the extreme back end of the key; in others it is put near the
balance rail according to the requirement. In some actions the lead is
omitted entirely; but in the best actions it is almost invariably present.
In the action of the grand piano the keys are leaded in front of the
balance rail instead of back of it. This is due to the fact that in the grand
piano the hammer rests in a horizontal position and its whole weight
must be actually lifted and the force of gravity overcome, while in the
upright, the hammer rests in a vertical position, only requiring to be
thrown forward.
G P, is the guide pin, generally of oval shape, with the longest diameter
in line with the key. The hole in the lower portion of the key, in which
the guide pin works, is bushed with bushing cloth and is made to fit so
closely that the key will not move laterally, yet not so tightly that the
key will not work easily.
Bm, is a wooden block called the bottom; sometimes called the
key-rocker. It is held in position by the two screws shown in cut by
which it can be adjusted or regulated.
E, is the extension communicating the motion of the key to the upper
part of the action. There are various ways in which the extension is
connected to the bottom. In this action, the extension is made round at
the lower end and fits snugly into a hole in the bottom upon a felt disc.
When the action is taken out, the extensions simply lift out of the holes,
and when it is put back it is necessary to enter each one in its place. In
other actions, the upper side of the bottom where the extension rests

has no hole but simply a felt covering upon which the extension rests;
in this case it is necessary to provide what is called an extension guide
which is hinged to the extension guide rail shown in the cut at the left
of the extension. In actions of this kind, the extensions remain in place
at all times and the trouble of placing them properly on the bottom
when replacing the action is obviated. Other methods also are
employed which are readily understood upon slight examination, but
are essentially similar to the above. Instead of the bottom, a capstan
screw is used in some actions as follows:
Cpn, is a capstan screw used in some actions in place of the bottom. It
is turned by inserting a pointed instrument in one of the four holes, thus
raising or lowering the capstan in regulating. The lower end of the
extension is felted. In such actions the extension is invariably provided
with the extension guide.
B, is the metal action bracket. The bracket is one solid piece of metal.
There are generally four brackets in the upright action. The brackets
rest on supports in and at the sides of the keybed, and are secured at the
top by large bolts,
BB, which go through the metal plate and into the wooden frame or pin
block. At the top of each bracket is an opening to receive this bolt and a
thumbscrew (not shown in the cut, being behind the hammer) which
fastens the action securely in position.
M R, is the main rail; so called because the main constituents of the
action are attached to it. (Everything designated as "rail" in the action
runs the entire length of the action in one solid piece.)
W, is the wippen. Those pieces upon which or by which the small letter
g is shown are the flanges. The one at the left of the wippen is called
the wippen flange. It is made fast to the main rail by a screw, and upon
it the wippen is hinged by means of a "center-pin" at the lower