When tested and found true, lift the blade by inserting a knife blade under it, again fasten to the board with unfinished side up, and again dress down. Before removing from the board, lay out the curved end to correspond with the curve of the head, and cut to line with a chisel.
Remove from board, finish curved end with sand-paper block. Bore hole h for hanging up, locate holes for screws, and drill just large enough to allow 1⁄2-inch round-head brass or blued screws to pass through. In attaching the head, make sure that the two parts are at right angles, and use thin copper burrs or washers under the screw heads.
If the blade is to have edges of a different colour, joint the maple on shooting board, and glue the strips to it, before planing to thickness. This should be done on a flat board, with paper between it and the blade. Glue the three pieces together, and drive 11⁄4-inch brads up close to and touching the outside strips, at intervals of four inches. By bending these slightly over the blade, considerable pressure will be obtained, tending to keep the pieces together while glue is hardening.
Then proceed to dress down, and true up as before. When the process is once learned, considerable pin money may be made by disposing of the squares, and that will help to buy material for other things.
Triangles made from single pieces of wood are absolutely unreliable. Referring to [Fig. 207], the 45-degree triangle shows the grain running up and down. As shrinkage takes place m will not change, but n will, and this will alter the angles; and besides a piece of thin wood this size will warp and make the triangle useless for mechanical drawing.
The 30-60 triangle illustrates the usual method of constructing a wooden triangle.
Aside from bisecting the 90, 60, and 30 degree angles to get the mitres, these joints, if simply glued, will be too weak for practical use. The edge view and dotted lines indicate a thin feather of wood glued into a saw cut made through the edge of each corner, the usual method of strengthening. It is a delicate operation, and is only recommended to boys who are fond of fine work.
A very serviceable section liner may be made from a wooden triangle by carefully cutting out of one side a rectangular opening, as shown in the detail. Make a piece of thin wood to fit this space, but 1⁄8-inch shorter, and fitted so as to move freely. By moving this block and the triangle, alternately, vertical or oblique lines can be drawn for sectioning, and they will be equally spaced. Other blocks varying in length will give a variety of spacings.
It is possibly one of the cheapest section liners, and the most satisfactory within the means of any one. Irregular or French curves may be made in thin wood. They should be drawn on the surface, sawed out with the coping saw, and sand-papered smooth. As their thickness should be but a trifle over 1⁄16 inch, they are very frail and easily broken. These curves can be easily made in sheet aluminum, and they will be much more satisfactory. This metal is handled similarly to thin wood, except that the saw must be a metal cutting blade.
Triangles may be made of the same material. Lay out the form with a sharp steel point or scriber, saw as close to lines as possible, and with a fine file finish to line. Then smooth the curves with fine emery paper wrapped around a lead pencil. To make straight edges, as on triangles, lay a sheet of emery cloth on bench, and rub triangle back and forth.