PLANES.
In workshop practice, planes are the tools chiefly used for smoothing the surface of wood after it has been sawn to approximate size. In its simplest form, a plane is a chisel firmly fixed into a block of wood by which it is guided in its cut, and the amount of wood taken off in the form of a shaving is regulated to a nicety. In fact, such a simple tool actually is used sometimes, when a proper plane of the requisite shape and of a suitable size cannot be procured. To make the construction of an ordinary plane quite clear, a section of one is illustrated by Fig. 154, in which A shows the section of stock; B, the wedge; C, cutting iron; D, back iron; E, the screw for fastening irons together; and F is the mouth through which the shavings pass upwards. A plane is simply a copying tool, and a notch in the plane-iron at once proves that the pattern produced corresponds with the edge of the plane-iron, and all the imperfections of this edge will be copied on to the stuff. In all planing operations the edge of the tool is the pattern, which is copied in reverse on the wood. If a hollow is required to be produced on the wood, a tool is used with a round edge of exactly similar form to the hollow we wish produced. In machine planing the pattern is the edge of the tool, which produces a similar surface upon the wood.
Fig. 154.—Section of Plane.
Fig. 155.—Jack Plane.
DIRECTION OF GRAIN IN PLANES.
For flat planes such as jack, try, and smoothing planes, the grain must be straight and, of course, run lengthways of the tool. The wood is selected from a centre plank of beech as near to the bark as possible; in all planes, the wood nearest the bark, that being the hardest part of the wood, becomes the sole or working surface. The wood is seasoned thoroughly, and never is used until at least three years after cutting. Moulding planes mostly work on the spring, and need not have the grain so straight as flat planes. Hollows, rounds, and rebate planes are exceptional, however, and should have the grain as straight as possible, because the rebate plane is cut right through, and is liable to cast or warp if not quite straight-grained; and most of the hollows and rounds, being thin, are liable to cast also if not of straight, mild, and well-seasoned wood. Wood for plane making should be as free from knots as possible.
Fig. 156.—Sunk Handle Jack Plane with Closed Toat.
JACK AND TRYING PLANES.
The jack plane (Figs. 155 and 156) is the first applied to the wood after it has been sawn. This plane is always employed to remove the roughness of the work before finishing up with trying and smoothing planes. It is made up of five parts—namely, the stock (which should be 17 in. in length), the toat or handle, the wedge, the cutting iron or cutter (2 1/8 in. broad), and back iron. Immediately behind the iron is a handle, which, in use, is grasped only by the right hand in planing fir; but in heavy planing, and especially in hard wood, it is necessary to place the left hand across the front of the plane to press it down, to cause the iron to take hold of the wood. When using both hands to the plane, the left is placed with the four fingers lying across the top near the fore end, the thumb passing down the near side. Well-seasoned beech is a suitable wood for the stock. The construction of the trying or trueing plane (Fig. 157) is almost exactly the same as that of the jack plane, but it is much longer, so as to produce truer surfaces. The following instructions on manipulating the jack plane apply equally well to the trying plane.
Fig. 157.—Trying Plane.
REMOVING AND REPLACING IRON IN JACK PLANE.
To remove the iron, the stock should be grasped by the left hand, with the thumb on the inside of the mouth, as shown by Fig. 158. The back of the plane may be rested against the body, whilst the front of the tool is gently knocked with the hammer (or mallet, by preference), which will loosen the wedge, and enable the iron to be withdrawn. Another method is to knock the front of it with face upwards smartly on the bench while holding wedge and iron in the left hand; one blow is generally enough. The iron, it will now be observed, consists in reality of two parts; the cutting iron is faced with good steel (see Figs. 159 and 160), and the back is of iron. Badger jack planes have irons as in Figs. 161 and 162. The back iron (see Figs. 160 and 162) screw fastens the irons tightly together, and it is for the purpose of regulating the thickness of shavings, as will be explained in a separate paragraph. To take the irons apart, place the wedge upon the bench, as at A (Fig. 163), and lay the iron screw uppermost upon it. Now loosen the screw with a screwdriver (do not take it out), and slide the back iron up until the head of screw will pass out at the hole made for the purpose. The unscrewing of a plane iron with a long driver is illustrated by Fig. 164. Sometimes a large screwdriver and a small hammer are required for unscrewing the iron and setting the plane; but by a few minutes’ work on the grind-stone, the flat pene of a hammer can easily be ground so that it will serve as a screwdriver, thus answering both purposes. When the iron has been sharpened (see pp. 54 and 55), screw on the back iron in the same manner that it was taken off (see Fig. 163), and place it in the groove or mouth of the plane, keeping it in position with the thumb of the left hand, the fingers grasping the face, as at Fig. 158. Now insert the wedge, and lightly tap it with the hammer. Place the end of the plane upon the bench, and draw the top towards the worker; now look down the face in the direction of the arrow, and the iron should be seen projecting about 1/16 in. Should it be more, gently tap the head of the plane, again driving in the wedge tightly. The tool is now ready for use. The two irons should be screwed perfectly tight (see Fig. 165); if they are left as in Fig.