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Page:Popular Science Monthly Volume 89.djvu/611

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Popular Science Monthly

��and has the same shearing action. The shape of the two types of teeth is shown in F"igs. 4 and 5. The best modern

���The teeth of a rip-saw act like small chisels to chop off the end grain of the wood

saws arc made thinner at the joint than at the heel (handle end) and the bhule tapers from the cutting edge to the back. This stiffens the saw where stiffness is needed, and saws made in this way need very little "set."

The rip-saw is designed to work with the greatest efficiency when cutting with the grain of the wood. The shape of its teeth is the result of exjjerience in combining such features as the strength of the tooth, the acuteness of the cutting angle, and the ease with which it may be sharpened. The steel in this .saw is softer than that in many other wooil- working tools, in order that it may be more easily filed and set. This necessi- tates fretjuent sharpening, particularly when the tool is used on hard woods. In general the rip-saw tooth has an included angle of 60 degrees, with the face at an angle of go degrees to the line of the teeth and to the blade. (Fig. 4.) This saw will not work successfully

���The cross-cut saw with its keen knife- shaped teeth cuts slowly across the grain

across the grain, as the teeth, having no shearing angle, tear the wood-fibers instead of cutting them, and leave a

��rough and jagged surface. It may be used, however, in making a diagonal cut, where it works much faster and nearly as smoothly as the cross-cut.

The cross-cut saw with its knife- shapctl teeth, cuts slowly across the grain, leaxing a smooth surface which for nian\- purposes does not recjuire any further finishing.

In all fine cabinet work an allowance should be made for chi.seling or planing the cut surface, to remove saw marks. When ripping a board, keep the saw cut about I 16 in. away from the line, and plane the edge true. To start a cut with the rip-saw hold the saw firmly and

���The arrangement of the tools in the cabinet back of the inner swing-door

move the teeth lightly over the edge of the board. Use the thumb of the left hand as a guide. If the saw is kept nearly parallel with the board it is not absolutely necessary to start with a back stroke.

A light, slow stroke is much more effective than a hard, quick one, which tends to buckle the saw and cause it to jam in the board. Sometimes, due to shrinkage, the board has a tendency to bind the saw in the "kerf," or cut. To remedy this, insert a .screw-driver in the "kerf" and rub a little heavy oil or grease on the blade of the saw.

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