The rack-pins should be of mahogany or oak, with a shoulder at each end, the necks fitting tightly in the holes provided for them already. These necks may be blackleaded, to facilitate removal.
All the holes may now be bored in the rack-board corresponding to our two wooden stops (Nos. 2 and 4), at the points marked long ago, when the grooving was finished; the board may be placed on its rack-pins, and the feet dropped into their places, adjusted, where necessary, with a half-round file. The pipes may then receive their feet one by one, and if your calculations have been correct and your measurements accurate they should stand in orderly array. Use the spirit-level, square, and plumb-line in planting the pipes, to ensure truly horizontal and perpendicular lines. The feet should not be actually glued into the blocks until the last little adjustments have been given.
In planting the metal pipes, holes 2 inches or more in diameter will be required in the bass, while those in the extreme treble will be little larger than a common quill. Adjustable bits may be bought, clever contrivances producing beautifully true circular holes (see Chap. II.). In the absence of these, we recommend you to use discs of stiff paper or cardboard, representing the exact size, as ascertained by callipers, of the conical foot of the pipe at about 5 inches from its lower extremity; from these discs the outline of the holes may be traced on the board, and all the holes, great and small, may be cut out with a pad-saw, or bored with common bits, in every case a trifle smaller than they are ultimately to be. Then, the rack-board being in place, each pipe may be adjusted in its position by using a half-round rasp, and similar or rat-tail files. With these you will easily give a conical form to the holes in the board.
Great care will be well bestowed in this operation. If, unfortunately, you cut any hole too large, line it with a morsel of soft leather. But every true workman will desire to resort as seldom as possible to this expedient.
Probably none of the metal pipes will require to be grooved off. But this you have attended to long ago. If any of them are grooved off, take care that the grooves are of ample size, that the wind may not be throttled.