Saws, as determined by their teeth, are of two general classes -crosscut and rip. The former class are used for cutting across the grain, the latter for separating the fibers along the grain.
Fig. 25. Effect of Chiseling Along the Grain.
Fig. 26. Effect of Chiseling Across the Grain.
An examination of Figs. 25 and 26 will indicate the necessity for differently shaped teeth for saws cutting across and along the grain. The rip-saw has the cutting edges of its teeth across the front of the teeth, and is in fact nothing more nor less than a lot of little chisels, cutting in rapid succession as the blade is pushed forward, Fig. 27. The handsaw or crosscut-saw is like the rip-saw in all respects except that the cutting edges of the teeth must be on the sides rather than across the front of the teeth, Fig. 28. Try the experiment of trying to cut a kerf across the grain by holding the chisel as in cutting along the grain, the reason for shaping the teeth with the cutting edges on the sides of the teeth will readily be seen. 12. Sawing with Hand or Crosscut-Saw and with Rip-Saw. - In using these saws, generally the board to be sawed will be placed upon a pair of trestles or "sawhorses." Place the knee upon the board and assume a position for ripping similar to that shown in Fig. 29. The index finger of the right hand should extend along the side of the saw to assist in guiding it; place the thumb of the left hand upon the board at the place the cut is to be made and the blade of the saw against the thumb lightly. Holding the cutting edge at an angle of about 60 degrees with reference to the surface of the board, begin the sawing with short, light, easy-strokes, gradually increasing their length as the kerf is formed, until almost the full length of the saw is used. Strive to keep the eyes, hand, and saw blade in one and the same plane. Should it become necessary to change the direction of the saw because of its not following the line properly, this can be done by gently twisting the blade as the sawing proceeds in the direction it should take. This twisting must be done with care or the blade will bind and kink. When nearing the finish of a kerf, shorten the length of stroke and lighten the weight of the saw by holding up on it, at the same time taking hold of the part being cut off, Fig. 30.
Fig. 27. Teeth of Rip-saw.
End View (Exaggerated).
Fig. 28. Teeth of Crosscut-saw.
In cutting a piece from a large board, rip-saw first and then crosscut to meet the ripped kerf, thus leaving on the main board all but just what is wanted. This practice is more economical and is less likely to result in a split piece.
Fig. 29. Position for Ripping.
Fig. 30. Position for Final Crosscutting.