Practical Organ Building

by W. E. Dickson

Take a piece of three-quarters or five-eighths board, the full length of the wind-chest, and wide enough for your twelve rollers when placed as we shall now direct. Dress it up, and give it two coats of priming. At its lower edge mark the exact centres of the key-tails from end to end of the key-board. At its upper edge mark the precise centres of the tails of the twelve backfalls on which the rollers are to act, fixing the board temporarily so that precision may be secured. Along the two side margins of the board (which has been squared up true) mark rows of dots at equal distances, say 1 inch or considerably less, according to the scantling of your rollers, which may be placed as close to each other as possible without actual contact when made to revolve through a small arc on their pivots. You have now all the data which you require, and may draw pencil lines showing the exact place of every stud on the board, the exact length of every roller, and the exact spots on each roller at which the arms must be inserted.

Fig. 36, in which x y is the key-board, the rollers and stickers being represented by lines only, shows that the longest roller, that of CC sharp, is placed by itself at the top. This is done in order to enable us to use a single stud, common to two rollers, throughout the board until we come to the last, which will stand alone. If the rollers of CC and of its sharp were thus placed in a line, running into a single stud, there would be hardly room enough for the latter, as the arms would be in immediate contiguity. By giving the CC sharp roller a place by itself, we get the following pairs: CC and DD sharp; DD and FF; EE and G; FF sharp and A; G-sharp and B natural; A sharp will have its own two studs. Thus we obtain a distance of fully 1¾ inch between the centres of the contiguous arms of these pairs of rollers; and if iron arms are used, there is room to drive in the pivot without meeting with the interruption of the screw in the heart of the wood.

When these measurements have been made, and lines drawn in pencil or chalk, the holes for the shanks of the studs may be bored, and the board cleaned over and perhaps repainted. When the work is complete, the cleanly planed rollers with their neat studs on the dark background of the board should present a pleasing appearance.

Sometimes the roller-board lies horizontally. It is then usually called a roller-frame. Fig. 37 is a slight sketch showing how a roller-frame may be united with squares in certain cases. a b is a key-board, acting by stickers on a set of squares, c, arranged in a bridge. d is another set of squares in a longer bridge under the pull-downs of a chest, e, let us say that of the second manual in an instrument of considerable size, placed at the back of the case, and possibly some feet from the player. f is a roller-frame, transmitting the touch by trackers to the extreme pallets right and left.

Fig. 37.

If economy of height is no object, however, the roller-board will be placed between the squares d and the chest e in the usual vertical position, or it may be above the keys.

Sometimes space is saved by inserting the roller-arms on opposite sides of the rollers, cutting apertures in the board through which one arm of each pair may protrude. This plan may be regarded as a compromise between the fan-frame and roller-board, the latter doing duty as a set of backfalls.

Fig. 38.