STANDARD MODERN AMERICAN GRAND ACTION.

It will be observed that the key (1) is supported upon a key-frame, part of which is clearly shown in the drawing. This frame is provided with a cloth strip at its rear end, also shown, and with a “balance rail” upon which the key is pivoted by means of a pin. The position of this balance rail must be such that the divisions of the key thus made are to one another as 3:2. The part nearest to the player’s finger is the longer. But such a proportion as this holds good only for the actual operative lengths of the keys from the front to the point where the sticker, or capstan screw is placed. For otherwise we have a distinct change in the mechanical relations of the parts of the lever-system, and this, of course, entails a corresponding change in the forces that are brought into operation. It is therefore necessary to have a standard length of key, as between the points mentioned, and this length is placed at 15 3⁄4 inches. But, in order to maintain the mechanical relations between the dimensions of the lever we must also consider the depth to which the key sinks in front, and also the height to which it rises at the back. If, then, we arrange that the depth in front shall be 3⁄8-inch full and the rise in the rear 1⁄4-inch full, we shall be able to maintain the position of the balance pin as already calculated. Such a proportion supplies the very best arrangement. In order to fix the proportions in the reader’s mind we repeat them in tabular form, as follows:

Inches
Length between front of key and balance pin9 9⁄20
Length between balance pin and capstan or sticker6 3⁄10
Total length of key between front and capstan or sticker15 3⁄4
Depth of fall of front portion of key3⁄8 full
Height of rise of back portion of key1⁄4 full

The front portion of the key is mounted upon a rail of the key-frame which is provided with a pin. This pin works in a mortise cut in the bottom of the front portion of the key and bushed with cloth. The pin is oval in form and adapted to be turned so as partially to increase the amount of space occupied by it whenever wear or age tend unduly to enlarge the size of the mortise.

The exact size of all the various action parts that are mounted above and in connection with the keys depends largely upon the exact interior dimensions of the grand pianoforte case. So that it becomes necessary carefully to measure the height from the key-bed to the level of the strings, and also the distance from the front of the keys to the line of damper lifter wires, and from there to the extreme rear end of the key-bed. Likewise the exact position of the middle string of each three-string group, the middle point of each two-string group and the position of each single string must be marked upon a stick for the guidance of the action-maker. The latter will then be able to effect the correct alignment of the hammers, the rise of the escapement lever and jack, and the exact position, in reference to these, of the other parts of the action. It will, of course, be understood that the proportionate dimensions of all the action parts depend upon the measurements that we mentioned just now, as well as upon the dimensions of the keys. The greatest care is therefore necessary in making these measurements.

GRAND PIANOFORTE ACTION WITH METALLIC ACTION AND DAMPER FRAMES, SOSTENUTO PEDAL DEVICE AND HAMMER SWINGING SOFT PEDAL ATTACHMENT.