21. The Jack-Plane.
—The jack-plane is about thirteen inches long. Where a full equipment of planes is at hand, the plane-iron of the jack-plane is ground slightly rounding as is shown in [Fig. 50 A]. The purpose of this plane is to remove rough or large quantities of wood and this shape of blade is best suited for that purpose. Of course the surface of the wood is left in hollows and ridges, and it is necessary to use another plane with a plane-iron ground straight and set shallower in order to smooth the surface.
In manual-training schools where the jack-plane is made to serve the purpose of smooth-plane also, the plane-iron is sharpened straight across and the corners slightly rounded, B, [Fig. 50].
22. The Smooth-Plane.
—The smooth-plane is shorter than the jack-plane. [Fig. 51]. It is used, as its name implies, for smoothing surfaces. As the straightening is supposed to have been previously done, the shorter length is no disadvantage. For fine work the cap-iron of this plane may be set as close as one thirty-second of an inch to the cutting edge of the plane-iron. The plane-iron should be set correspondingly shallow.
Fig. 51.
23. The Jointer.
—This plane is used for straightening long and uneven stock. It is most commonly used for preparing the parts for glue joints. [Fig. 52].
