1. Crosscut and rip saws. Woodworkers use two types of saws, one to cut across the grain, the other to cut lengthwise of the grain of wood. They are called, respectively, crosscut and rip saws.

2. The saw kerf. The opening that either saw makes (due to its thickness and the set of the teeth) in passing thru a board is called its kerf.

Since this kerf has width it must always be considered and an allowance made when getting out material or cutting joints.

Can you get two six-inch pieces out of one twelve inches long? Why?

Fig. 16.

3. Always keep the kerf in the waste stock.

You should always try to saw to the center of the knife or gage line. (See (a) Fig. 16.) If you do the work accurately, you can see the burnished streak left by the knife or gage line after the sawing is complete. (See (b) Fig 16.)

4. The teeth of the crosscut saw are filed to a point. (See Fig. 17.)

These points are arranged to come alternately, first over one side of the blade and then over the other. This is done to cause the teeth to cut the fiber of the wood first at the limits of the kerf, just as the spur of the auger bit first cuts a circle on the wood before the lip removes any shavings; and for the same reason, namely, to prevent tearing the grain of the wood After the points of the teeth have severed the fiber of the wood, the backs of the teeth crumble and carry out the wood of the kerf in the form of sawdust.

5. The rip saw has teeth filed to a cutting edge. (See Fig. 17.) They are formed like chisels and cut in the same way.

Plan

Front

Side Crosscut Saw

Plan

Front

Fig. 17. Side Rip Saw.

6. A dull saw, either crosscut or rip, is put into condition by:

(1) Jointing the teeth, i. e. running a file over the teeth lengthwise of the saw to bring them all to the same length.

(2) Setting the teeth, i. e. bending just the very points of the teeth alternately to the right and to the left. This is done to prevent the saw binding in the kerf. A saw requires more set to work well in soft, wet wood than in hard, dry wood. Why?

(3) Filing the teeth to correct shape.

Important: Wherever accurate sawing is required all lines should be run with the knife or marking gage. Either tool, when sharp, opens somewhat the fiber of the wood, forming a V-shaped groove with burnished sides. After sawing, these burnished surfaces should show. (See (b) Fig. 16.)

Reference Work: Look up and report upon the following:

Compass, keyhole, bow-turning and coping saws. Also the back saw and the miter box. Make a collection of pictures taken from trade catalogs showing as many varieties of saws as possible. Write to Henry Diston & Sons, Philadelphia, and ask for their Hand Book on Saws. It describes the manufacture and explains the use and care of both saws and files. It is free to schools and teachers.