Practical Organ Building

by W. E. Dickson

THE WIND-CHEST.

The somewhat wearisome task of boring more than 250 holes in the sound-board being now assumed as accomplished, we may take the upper boards and sliders apart, and retouch the holes here and there, as required, with the hot iron. The apertures of the holes in the interior of the channels must be thus attended to, as the boring-bit may have occasionally torn the wood and left rough edges. Upon the faintest suspicion arising in your mind of any flaw or crack set up in any channel during the business of boring, smear over the whole interior of that channel anew with thin glue, letting it flow as before into the angles. A running of the wind from one channel to the next is, as we have said, the most provoking of all defects, and might compel us to pull the whole of the organ to pieces after it was set up.

The running of wind from one pipe-hole to an adjacent one, either under the slider or between the slider and upper board, though very annoying, is a much less serious evil. As a precaution against its occurrence, it is usual to make little cuts or canals running tortuously all across the table from edge to edge between the pipe-holes, and to make similar canals or ducts across the under side of the upper boards, so that no vagrant wind can pass from a hole to its neighbour in any direction without encountering one of these little cuts, and being conducted by it to the edge of the sound-board, where it will escape harmlessly. If the planing of all the surfaces is absolutely perfect, these cuts should be unnecessary, and we have seen highly finished sound-boards in which they were omitted; but we must recommend their introduction by all young beginners. They may be neatly and quickly formed by using the V-shaped tool common among sculptors in wood, and procurable at any good tool warehouse. Its two edges should be exceedingly keen. The cuts may be about ⅛ inch in depth.

After this is done, the movement to and fro of the sliders should be regulated by cutting a little slot in each of them, and letting a very stout pin of wood or iron into the table within the slot, so as to stop the slider at the exact points. Of course all your sliders will have the same extent of play, say 1 inch, less or more, according to your arrangement of the pipe-holes. You will probably have so far thought over your whole work as to be able also to cut the openings or slots in the projecting ends of the sliders by which the mechanism for drawing them in and out will be applied to them. We shall show, hereafter, one or two different ways of effecting this movement to and fro.

After this, take some good blacklead in powder, and with a stiff brush rub it over every part of the table until the whole surface has a lustre like that of a well-cleaned boot. Treat the sliders and the under side of the upper boards in the same way. This application of blacklead greatly diminishes friction between wooden surfaces brought into contact. Some operators mix the blacklead powder into a thick paste with spirits of turpentine, or with water. We prefer using it dry, but we heartily endorse M. Hamel's complaint that it is difficult to procure blacklead of good quality. That which is sold for household purposes is often little better than a gritty sand.

When the blacklead has been applied, the bearers may be pinned down in their places with small brads. The holes which you have bored for the screws will be conspicuous in them: over each of these holes, using thin glue or paste, place a slip of paper, extending 2 or 3 inches along the bearer on each side of the hole. The use of this is to hold up the upper board, in order that the slider may not be pinched so tightly as to be immovable. The upper boards may then be laid upon the bearers, with the sliders in place, and the screws turned until the sliders can be made to glide to and fro with smooth and easy motion.

Our bench, let us assume, has been swept and cleaned up after this blacklead rubbing, and now we turn over our work and proceed to a new class of operations.

We have to attach to this lower side of our sound-board a shallow box of the same length, and about 3 inches deep, called the wind-chest, which is to contain the apparatus by which the admission of compressed air to the channels is governed, and which is in direct communication with the bellows by means of a wooden tube called the wind-trunk.