Elements of woodwork

by Charles A. King

(B.) The shape of the cutting edge of the plane cutter has an important influence upon its efficiency. Imagine the edge divided into three equal parts: the middle part should be perfectly straight, or almost imperceptibly rounded; the two outside thirds should be slightly and gradually rounded until the corners of the iron are so short that there will be no danger of their projecting below the face of the plane. This gives the edge an elliptical shape, as shown in Fig. 53, which is somewhat exaggerated, as the shape shown is about that which would be seen if a moderately coarse jack plane were held as in Fig. 49.

(C.) In order to insure fine work, the cap iron must be fitted so carefully to the face and the edge of the cutter that, if necessary, it may be placed less than ¹⁄₆₄th of an inch from the cutting edge, though this would rarely be required except upon very cross-grained wood.

In fitting the cap iron to the top of the cutter, a very fine, sharp file should be used. The filing must all be done upon the under side of the cap iron, at the places where it rests upon the face or top of the cutter; or, if preferred, the cap may be very carefully bent, but unless there is considerable fitting necessary, and unless the joint is perfected by the use of a file, this method is not recommended.

If sufficient care and skill are exercised, a plane may be sharpened and adjusted so finely that a veneer of .01” or less in thickness of bird’s-eye maple, burl walnut, ash, or similar wood may be smoothed. It is not wise, however, to spend the time necessary to keep a plane sharpened and adjusted to do this sort of work, as a scraper and sandpaper, or the latter alone, is the most economical way to smooth woods of such nature.

(D.) To remedy clogging of the mouth, remove the conditions which cause it; simply digging out the shavings is useless. An improperly fitted cap iron is one of the principal causes of trouble; the cutter may be ground so thin that when it is forced against a knot or hard place, the iron chatters, which allows the shavings an entrance under the cap iron. In this lies the only real advantage of a wooden plane over the modern iron plane, as in the former the iron is much thicker and stiffer. The cap iron may be so thick that it causes the shavings to curl too much, or the frog may be set too far to the front, which will make the mouth too small. This latter may be remedied by moving the frog back, but in a wooden plane, the mouth and the throat would have to be cut larger in order to allow the shavings to clear themselves properly.

Fig. 54.—Jack Plane.

41. The jack plane (Fig. 54) generally is 15” long, and its ordinary use is for the purpose of roughing out a piece of wood for jointing or smoothing. If it is properly sharpened, it may be used as a smoothing plane, or as a jointer upon small work, as it is capable of doing as good work as any plane.

The jack plane generally is ground more rounding, and the cap set farther back than in the other planes, especially if it is to be used upon rough work.

42. The jointer.—(A.) This tool is from 20” to 26” long, and is used to straighten edges and surfaces, or to fit them together. The shape of the edge of the cutter of this plane should be but slightly elliptical, less so than the jack plane or the smoother, unless the two latter are fitted for doing very fine work.