To Guide The Saw. If the saw tends to run off the line, the blade may be slightly twisted in the direction it ought to take, as shown by Fig. 152. It will immediately respond by a change in its course. The correction should be made as soon as the error is discovered.

137. To correct the Angle of the cut, the saw should be bent, as shown by Fig. 153, and at the same time moved vertically, as shown by Fig. 154, instead of in the usual direction, which is indicated by the dotted line ab in the same figure.

138. Rip-sawing on the line ab and a'b', Face C, Fig. 137.-Start the saw on the lines ab and cd (the latter shown in End Elevation). By following the first line the proper direction of the cut will be insured, and by keeping on the second the piece will be cut square with the working-face. The saw once started, the truth of the angle may be occasionally tested by the try-square applied as shown by Fig. 155. Attention given to this matter at first, will soon make the operator sufficiently skillful to judge the angle accurately enough for most work.

After cutting on the line ab, cut also on the line In sawing a piece from one end to the other in one cut, the saw, in coming out, should not be allowed to injure the trestle. This danger may be met by slanting the board so that it will be supported by one corner, thus leaving an open space between the trestle and the point where the cut will end, as shown by Fig. 156.

Fig. 153

Fig. 154

Fig. 155

Fig. 156

Plan.

Elevation.

139. Cross-cutting on the lines ef and gh, Face C Fig. 137. Observe the general directions that have already been given.

When the piece that is being cut is almost divided, there is danger that the uncut portion may break and splinter. This tendency must be guarded against by properly supporting the work, either by the hand or by a suitable arrangement of the trestles.

Exercise No. 4. - Planing (66-74). The stock required is the pieces resulting from Exercise No. 3.

140. In grasping a plane, there is always shown a disposition to place the thumb of the left hand on the right side of the plane. This should not be done; for, as will be seen by Fig. 157, when the plane is drawn back, the arm, by contact with the body, becomes stiffened and the motion of the plane restricted. The hand, therefore, should be so turned as to bring the thumb on the left side, as shown by Fig. 158. Held in this manner, the plane may be easily carried well forward and well back.

Fig. 157

Fig. 158

When the surface of the work is large, begin to plane at its right-hand end. With a series of easy strokes pass across the face of the work, then step forward and take a second series of strokes, and so on until the whole surface has been passed over. In the first series of strokes it is necessary to draw the plane off the work, as shown by Fig. 159. In doing this, sufficient pressure must be exerted in the direction of the arrow to overcome any tendency to tip, as indicated by the dotted outline; in the last series of strokes the wrist may, for the same reason, be rested easily on the back of the plane. To make the strokes between the ends properly, the plane should be lifted so that the shaving may be finished before the forward movement of the plane ceases. The plane need not be lifted bodily from the work. The natural, slightly-upward movement of the arm when stretched out, as shown by Fig. 160, will accomplish all that is necessary.

Fig. l59

Fig. 16.0

If the plane is allowed full contact with the work on the backward stroke, a dulling effect on the cutting edge is produced, especially if the work is rough and gritty. Under such circumstances, it is better to raise the plane from the work entirely, or turn it on its edge, or draw it back in the position shown by Fig. 160. On small, clean surfaces, however, it is best to disregard this caution, since sharpening takes less time than placing the plane before beginning each stroke.

In planing a narrow surface, for example, the edge of a board, difficulty in keeping the plane on the work may be overcome by grasping it in such a way that the fingers of the left hand, while pressing against the face of the plane, may maintain a light contact with the work, as shown by Fig. 161.

141. The mouth of a plane sometimes becomes clogged, and, as a result, the cutting ceases. This may be caused by a dull cutting edge, which scrapes off fibers which it cannot cut; or by the low set of the cap on the iron; or by a bad fit between cap and iron, which allows a shaving to find its way between them, thus forming an obstruction to the passage of other cuttings. In new planes, the stoppage may be due to narrowness of the mouth, which will not allow a thick shaving to pass. It should be remembered, however, that narrowness of mouth is an element in the production of smooth work, and for this reason the opening should be no wider than is absolutely necessary.

To preserve the face of the plane, apply occasionally a few drops of lubricating oil.

142. Jointing the sawed edge of the 1 3/4" X 3" X 16" piece from Exercise No. 3, to finish at 1 3/4" X 2 3/4" X 16". Set the lines all around the piece, as ef and bg. Fasten the piece in the vise with the sawed edge up; plane nearly to line with the jack-plane and finish with the fore-plane.

Fig. 161

Fig. 163 gauge at 2 3/4" and from the working-face B, Fig. 162, gauge.

143. Planing to a Square each of the four 1 3/4" x 2" X 16" pieces from Exercise No. 3, their finished size to be 1 5/8" X 16" X 16". Select a straight face, or, if none is exactly right, correct the best and mark it as a working-face. Let this be done on each of the four pieces. All old marks are to be planed off and new ones made as needed. Suppose Fig. 163 to represent an end of one of the pieces, and let A be its working-face. With the fore-plane, joint B from A, and mark B as a second working-face. Repeat this operation on each of the other pieces. Set the gauge at 1 5/8" (the width to which each side is to finish), and from the working-face A gauge a line on B. From working-face B joint C to line, and perform this operation on each remaining piece. From B as a working-face with the gauge set as before, produce lines on A and C, and plane D to these lines. This done, the four pieces should be of the same size, and true squares in section.

144. Whenever a series of similar operations is to be performed on two or more pieces, the method developed by the foregoing exercise should always be followed. By carrying all the pieces along together, the work will be most easily and most rapidly accomplished.

145. Smooth Surfaces cannot always be produced by a plane. The presence of knots or a crooked grain causes the work to split in advance of the cutting edge, and a rough surface results. A sharp plane set to take a fine shaving, will do much to remedy this evil, but it cannot be entirely overcome. Surfaces, such as a table top or a door panel, which are not required to be true, may be made as smooth as possible with a plane, and the rough spots reduced afterwards by means of a hand-scraper, applied as shown by Fig. 164. A surface that is required to be true as well as smooth, is best smoothed by a scraper mounted like a plane-iron. Such a scraper may be made to act uniformly over an entire surface, whereas the hand-scraper is useful on rough spots only. The requirement of both truth and smoothness, however, is very unusual. True surfaces are necessary about a joint, but the parts of a joint are smooth enough as left by a plane. On the other hand, a surface that is required to be perfectly smooth, is one which is made to be seen, and will be sufficiently true if the eye does not detect its inaccuracy.

Fig. 163