The process of shaping the belly is the most delicate and requires more skill than all the rest. In the first place you must follow the grain of the wood. If the back twists and undulates, your cut must do the same. The feather of the grain must never be reversed, but descend by perfect gradation from handle to tip.
Where a knot or pin occurs in the wood, here you must leave more substance because this is a weak spot. If the pin be large and you cannot avoid it, then it is best to drill it out carefully and fill the cavity with a solid piece of hard wood set in with glue. A pin crumbles while an inserted piece will stand the strain. If such a "Dutchman" be not too large nor too near the center of either limb, it will not materially jeopardize the bow. If, in your shaving, you come across a sharp dip in' the grain, such that will make a decided concavity, here leave a few more layers of grain than you would were the contour even; for a concave structure cannot stand strain as well as a straight one; the leverage is increased unduly.
The following measurements, with a caliper, are those of my favorite hunting bow, called "Old Horrible," and with which I've slain many a beast. The width just above the handle is 1-1/4 by 1-1/8 inches thick. Six inches up the limb the width is 1-1/4, thickness 11-1/16.
Twelve inches above the handle it is a trifle less than 1-1/4 wide by 1 inch thick. Eighteen inches above the handle it is 1-1/8 wide by 7/8 thick. Twenty-four inches above it is 15/16 wide by 3/4 thick. Thirty inches above it is 11/16 by 9/16 thick. At the nock it is practically 1/2 by 1/2 inches.
Having got the bow down to rough proportions, the next thing is to cut two temporary nocks on it, very near the ends. These consist in lateral cuts having a depth of an eighth of an inch and are best made with a rat tail file.
Now you can string your bow and test its curve.
Of course, you must have a string, and usually that employed in these early tests is very strong and roughly made of nearly ninety strands of Barbour's linen, No. 12. Directions for making strings will be given later on.
It is difficult to brace a new heavy bow and one will require assistance. In the absence of help he can place it in the vise, one of those revolving on a pivot, and having the string properly adjusted on the lower limb, pull on the upper end in such a way that the other presses against the wall or a stationary brace, thus bending the bow while you slip the expectant loop over the open nock. Or you can have an assistant pull on the upper nock, while you brace the bow yourself.
In ancient times, at this stage, the bow was tillered, or tested for its curve, or, as Sir Roger Ascham says, "brought round compass," which means to make it bend in a perfect arc when full drawn.
The tiller is a piece of board three feet long, two inches wide, and one inch thick, having a V-shaped notch at the lower end to fit on the handle and small notches on its side two inches apart, for a distance of twenty-eight inches. These are to hold the string.