Fig 70 Gumming A Crosscut

harden the metal that the file will not cut it. This is indicated by the blue color which the blade assumes where the grinding is being done. The amount to grind from a gullet is partly determined by the particular saw at hand. Effort should be made to grind the gullets and file the teeth to their original shape and size. In doing this work, very little pressure should be placed on the side of the gummer, as it is a rather thin stone, and it will not stand as much pressure at the side as the thicker stones which are used for general grinding work. It is not necessary to mark out each

FIG. 71. EFFECTS OF FITTING A SAW. A, ACTUAL SIZE AND SHAPE OF SAW BEFORE FITTING. B, THE SAME SAW AFTER FITTING

ing the work carefully, the eye will judge the size and shape required to make the work uniform.

The actual shape of a saw, just as it had been used, is shown at A, Figure 71. It may be noted that drag tooth No. 1 is more than 1/16 in. shorter than the cutting teeth, and that drag tooth No. 2 is about 1/32 in. longer than the cutting teeth. The points of the teeth and of the rakers had been filed many times, but the gullets had been neglected, so that not enough space remained in the gullets to hold and to carry out the sawdust. In fitting the saw, it was gummed and filed, as shown at B, with the %-in. emery gummer.

Jointing the Saw

The second operation in fitting a timber saw is that of jointing. This consists in running the side of a flat file lengthwise over the points of the saw teeth often enough to bring the tops of all the teeth in line. When the point is filed from a tooth, a small,

The teeth, being large, make it difficult to hold a file in the hands, as is done in fitting handsaws.

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