Practical Organ Building

by W. E. Dickson

A glance at Fig. 2 will enable our readers to draw scales for themselves for the Stopped Diapason, and for other wooden stops which may follow it, from a few given data, and to suit circumstances. A minute or Chinese accuracy is not requisite. The vertical line of any convenient length being drawn upon the paper, the width and depth of the CC block are measured off upon a horizontal line drawn at its lower extremity. Eighteen divisions being marked upon the vertical line, the half-width and half-depth of the CC block are measured upon another horizontal line drawn at the eighteenth mark. These points being joined by straight lines, and horizontal lines being drawn at each of the marks parallel to the others, we shall have the widths and depths of the blocks of all the pipes from CC to Clef F inclusive, viz. eighteen blocks. The next eighteen blocks will be sized in a precisely similar manner, and as three times eighteen is equal to fifty-four, the whole stop may be divided into three sections of eighteen pipes in each section, and it may be for our convenience to make one section at a time.

There are two methods of working together the block and the four boards which form the pipe. We will give them both, and decide between them.

First method. Cut out the board for the back, and dress it carefully to the exact width of the block. Glue the block to the lower extremity, and when the glue is dry dress up all perfectly flush. Cut out the side boards as wide as the depth of the block with the thickness of the back board added to it. Glue them to the sides of the block and to the edges of the backboard, obtaining a perfectly close joint by using wooden clamps and wedges as in gluing up a violin, or by other obvious contrivances. When the glue is dry dress up the front edges flush with the block, and glue on the front board, which will be cut out as wide as the block together with the thicknesses of the side boards. The front board must overlap the upper edge of the block by about ⅛ inch or more. If all this is carefully done according to the rules of good joinery the result should be a neat and strong pipe, truly rectangular at its upper or open extremity. Brads or sprigs are not to be thought of in pipe-making, unless, indeed, in the very exceptional case of organs intended for tropical climates.

Second method. Cut out first the two side boards the width of the depth of the block, and glue them to it. Dress the edges flush with the block, and glue on at once the back and front boards, obtaining irreproachable joints as before, and taking infinite care that the upper extremities of the side boards do not approach each other. In making our smaller pipes (say from Middle C upwards), we are in the habit of straining whip-cord or stout hempen string round them, winding it first upon a loose pipe-foot or smooth tool-handle to avoid cutting the hands; and we ensure a correct aperture at the top by placing within it a thin slice cut from the block itself, or by introducing the stopper if it has been already prepared of the same size as the block. The notches made by the string upon the edges of the soft pine-wood are easily removed when the finished pipe is dressed over with a fine plane.

We have no difficulty in giving our decision in favour of the second plan, which avoids the four tedious dryings of the glue, and which admits more readily of pressure being applied to the freshly glued joints. But in making open pipes, which have not to bear the driving-in of a stopper, there is much to recommend the first method.

This point being settled, we may cut out the side boards and prepare the blocks for one of our divisions, let us say the middle section, from Clef F sharp to the natural below Foot C. Blocks of this moderate size will be best made by taking a piece of wood of suitable character, long enough for six or more, and by dressing it down as each block is cut off, making careful and constant use of the gauge, the square, and the callipers. We like to form the throat with a centre-bit after the pipe is put together. The thirty-six boards will be glued to the eighteen blocks, and while the glue is drying we can prepare the backs and fronts. The bevelled lip of the latter will be left uncut until all the pipes have been glued up and dressed over, and the top edges nicely cleaned off and made true. But as there will be, doubtless, a most pardonable anxiety to hear the sound of one pipe, we will here explain that the height of the mouth of each pipe must be equal to one-third of its width; thus the mouth of the pipe measuring one inch and a half across the block (A in our scale) will be ½ inch in height. In measuring the height of the mouths, a pair of proportional compasses with sliding centre, or common dividers set to thirds, fourths, and fifths, will be useful if not necessary. The slope of the bevel is not of great importance. Cut it with a sharp chisel, taking care not to injure the block, and leave the lower edge or lip rather blunt. A sharp and pointed knife may be employed in cutting the lip truly, guided by the square. The use of fine glass-paper is permissible here to smooth all these parts nicely.

The throat having been formed in the face of the block, about 1 inch from its lower end, bore the foot-hole in the bottom of the block clear into the throat, beginning with a small borer, and enlarging the hole cautiously, as rough and hasty proceedings might split the block at this point, especially in the case of small pipes.

Prepare the cap from a suitable bit of mahogany, oak, or other close-grained wood, and hollow out the back of it with a chisel as shown in d, Fig. 1. Form the flue or wind-way through which the air is to pass to the lip by filing away the edge left at the top of the wedge-shaped hollow, trying your work by placing the cap against the side of the pipe or any other flat surface. The flue must not be wider than 1⁄16 inch at Tenor C, and must be reduced as we ascend the scale until it will hardly admit a slip of thin paper. It will not be so much as ⅛ inch wide even at CC.

Perhaps the stopper has been already prepared of the same size as the block, and has been formed into a knob at top, or turned in the lathe, or, in the case of the larger pipes, fitted with a turned handle glued into a hole bored for its reception. Dress off the angles of the stopper in order to allow room for the soft white leather with which it is covered to fold itself in the corners of the pipe. We generally rasp our stoppers, leaving them rough that the leather may cling to the stopper and not to the pipe. The leather cannot be too thin if it is soft, and if the stopper fits closely. Rub the interior of the top of the pipe with a bit of tallow-candle, and introduce the stopper cautiously. It should slide within the pipe at once easily and with accurate fit, and if your joinery has been good there should be no fear of splitting the pipe or of opening the joints.

The cap when finally fitted will have its upper edge about ⅛ inch below the upper edge of the block. On applying it in this position, holding it there with your fingers, or tying it on with string, and blowing gently into the foot-hole, you will have a pleasant fluty musical note. Probably a little chirp or whistle will be heard before the note comes on. The removal of this defect belongs to the important operation called voicing, of which we shall treat hereafter.