Piano Tuning | Page 6

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 end. The center-pin in the wippen is driven through a hole in which it fits tightly and immovably in the middle part, and it (the center-pin) is consequently stationary in the wippen. The flange extends down at the sides of the wippen and the holes in flange are made large enough to receive bushing cloth in which the center-pin works freely but not loosely. All flange joints are of this nature; some, however, are provided with a means for tightening the center-pin in the middle portion of the joint.
j, is the jack. The purpose of the jack is to communicate the motion of the wippen to the hammer. The precise adjustment of the jack and the adjacent parts upon which