Fig 68 Championtooth Timber

"champion tooth," which has two cutting teeth between each pair of rakers, is shown in Figure 68.

To cut properly, a saw must meet the following requirements:

1. All cutting teeth must be the same length, so that each tooth will do its share of the cutting.

2. Each cutting tooth must be filed to a point.

3. All rakers must be of a uniform length.

4. The rakers must be shorter than the cutting teeth by an amount suited to the kind of wood the saw is to cut.

5. The gullets, or spaces between teeth and rakers, must be deep enough to carry the wood in the saw kerf which is loosened by one stroke of the saw.

Gumming the Saw

It takes so much time to gum a crosscut saw with files, and the work is so tiresome, that few men will attempt it. Observation reveals that few saws are gummed, hence there is not sufficient space between the teeth to carry the sawdust that is produced by each tooth. The result is, that the sawdust is crowded against

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FIG. 69 A, REST FOR GUMMING CROSSCUT SAWS A AND B USED FOR GUMMING CIRCULAR SAWS

FIG. 69 A, REST FOR GUMMING CROSSCUT SAWS A AND B USED FOR GUMMING CIRCULAR SAWS

the sides of the saw kerf and, consequently, the saw pulls hard.

To gum the saw is an easy and simple job if an emery-wheel stand is at hand. A special saw-gumming wheel is necessary, as the grinding wheel is too thick. The gumming wheels are made in a variety of thicknesses; %, and % in. are the most common. A %-in. gummer, 8 in. in diameter, has proved to be satisfactory.

To gum a crosscut saw, place the saw on a rest which will support the blade almost the entire length. It should be high enough to support the saw at a height equal to the center of the grinder. A very satisfactory rest is shown at A, in Figure 69. Two pieces of 2 by 4 are nailed together. The lower one is 1 ft. long, and has pegs fitted into the bottom to fit the same holes as are used in the other homemade toolrest which is used for the farm-tool grinder. The upper piece of 2 by 4 is 4 ft. long. The saw is placed flat on the rest, and the saw crowded lightly against the grinder, as shown in Figure 70. It is good practice to do some grinding in a gullet, and then move the saw to a different point, thus allowing the blade to cool. If the entire amount of grinding is done in one gullet at one time, the tendency is to heat the blade and so

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