SAWS.
=11. Saws.=--Saws which are used in cutting across the grain are called
crosscut; those which are used in cutting parallel to the grain are
called ripsaws. Fig. 24. Upon the blade of a saw, near the handle, will
be found a number. This represents the number of points to the inch.
Points should not be confused with teeth, for there is always one more
point per inch than there are teeth.
[Illustration: FIG. 24.]
To prevent the sides of a cut or kerf from binding the saw, the teeth
are bent alternately from side to side, that the opening may be wider
than the blade is thick. The saw teeth are then said to have “set.” To
do good work, a saw should have no more set than is necessary to allow
a free movement. Fig. 25. Damp, spongy lumber will require considerable
set, while well seasoned lumber necessitates but little.
[Illustration: End view--(Exaggerated)
Edge view
Side view
FIG. 25.]
The rake, or pitch of the teeth of a saw is the degree of slant which
the cutting edges possess with reference to an imaginary line passing
thru the points of the teeth. Fig. 25. The amount of pitch given will
depend upon the use to which the saw is to be put, whether for ripping
or cross cutting, and somewhat upon the hardness or softness of the
wood to be cut. Fig. 26 shows the saw in proper position. It should be
held in the right hand with the left hand grasping the board, the thumb
of the left hand acting as a guide in the beginning. The thumb should
be held firmly on the board and the blade of the saw should be pressed
lightly against it. The cutting edge of the saw should be held at an
angle of about forty-five degrees to the board and should be started
on a backward stroke. The first few strokes should be short ones,
increasing gradually in length.
[Illustration: FIG. 26.]
If the tool is sharp, but little pressure will ever be required and, in
starting, the tool must be held up so that its weight shall come upon
the wood gradually. Saws can be guided better if the index finger of
the right hand is allowed to extend along the side of the handle. Test
occasionally, sighting down the saw blade to see that the sides of the
saw are at right angles to the surface of the board. A try-square may
be used by the beginner, as shown in Fig. 26.
If the saw does not follow the direction of the line, the blade should
be slightly twisted, as the sawing proceeds, in the direction it ought
to take. This must be carefully done so as not to cause the blade to
bind and kink. In sawing a board which has been fastened in the vise,
the most convenient position is obtained by sawing at right angles to
the surface. Unless the saw has considerable set, difficulty will be
experienced in changing the direction of the cutting should this be
necessary. This may be overcome by lowering the handle so that the
cutting edge shall make the same angle with the board as when the board
rests on trestles.
When making a long cut, should the kerf bind, a wedge may be inserted
as shown in Fig. 26.
All saws will work easier and will be found less likely to rust if
their sides are rubbed occasionally with an oily rag or a piece of
tallow.
[Illustration: FIG. 27.]
=12. The Crosscut Saw.=--Fig. 25 shows the teeth of a crosscut saw.
This saw is filed so that the cutting edges are on the sides of the
teeth. Every tooth is sharpened to a point, one on the right side, the
next on the left, giving two parallel lines of sharp points with a
V-shaped groove between.
The pitch given the teeth of a crosscut saw will vary with the hardness
or softness of the wood which is to be cut. For all-around use the
amount of slant is about one-third of the whole tooth. Fig. 27.
=13. The Rip-saw.=--The teeth of the rip-saw are chisel shaped, Fig.
28, and are made by filing straight across the blade. The front or
cutting edges are filed so that they are square, or at right angles to
an imaginary line passing through the points of the teeth.
[Illustration: FIG. 28.]
=14. The Back-saw.=--The back-saw, or tenon-saw as it is often called,
has a thin blade strengthened by a heavy steel back piece. It is used
upon work requiring delicate, accurate cutting, Fig. 29. Fig. 30
shows the shape of the teeth, which differ slightly from those of the
cross-cut. These teeth are suitable for both cross-cutting and fine
ripping. But little set is given the teeth of the back-saw.
[Illustration: FIG. 29.]
[Illustration: FIG. 30.]
In using this saw, Fig. 31, hold the work firmly against the stop of
the benchhook with the left hand, guiding the saw with the forefinger
or thumb placed against the blade just above the teeth. Begin on the
backward stroke, holding the handle end of the saw highest. Begin at
the farthest corner, using short, easy strokes. Gradually lower the
handle to a horizontal position, meanwhile increasing the number of
teeth used, but continuing the slow, regular strokes.
[Illustration: FIG. 31.]
[Illustration: FIG. 32.]
[Illustration: FIG. 33.]
In accurate cutting, Fig. 32, where no paring or block-planing is to
be done, the saw teeth should cut just by the line, with the kerf in
the waste, but with no wood between the line and the kerf. To allow
for paring or block-planing, saw about one-sixteenth of an inch in the
waste. Fig. 33.
[Illustration: FIG. 34.]
[Illustration: FIG. 35.]
When ripping, place the piece in the vise and begin sawing as indicated
in Fig. 34. Place the saw so that just the whole of its thickness is in
what is to become waste wood. Begin sawing as was done in crosscutting.
Gradually lower the handle, while sawing, until most is being cut from
the side nearest you. Fig. 35. Reverse the wood several times, working
down one side then the other until the cross lines are reached. Fig.
36 illustrates the result of good and bad sawing.
[Illustration: Good Sawing
Bad Sawing
FIG. 36.]
=15. The Turning-saw.=--The turning or bow-saw is used for cutting
along curved lines. Fig. 37 illustrates the manner of holding this saw.
The sides of the blade must be held at right angles to the surface of
the wood. Either or both handles may be turned, thus turning the blade
with reference to the frame. Avoid turning the blade, however, as much
as possible and see that the blade is not twisted by turning one handle
more than the other.
[Illustration: FIG. 37.]
This saw may be used for cutting enclosed curves by boring a hole,
releasing one end of the blade and inserting it thru this hole then
replacing it in the saw frame.
As the cut of the turning saw is not very smooth, it is advisable to
leave about one-sixteenth of an inch between the kerf and the line, to
be removed later with the spokeshave.
=16. The Compass Saw.=--The compass saw, Fig. 38, is better suited for
inside curve sawing. Its use requires a steady hand, else the thin
blade will buckle and break.
[Illustration: FIG. 38.]
=17. Saw Filing.=--Learning to sharpen a saw is a difficult thing--so
difficult that it is not considered within the province of a book
on elementary woodworking to treat of it. One who uses saws, ought,
however, to know the steps which are taken to put a saw in order.
[Illustration: FIG. 39.]
The teeth are first set. Fig. 39 shows a common form of saw-set in
position. Beginning at one end of the saw, every other tooth is bent
outward by means of this instrument. The saw is then reversed and the
remaining teeth are similarly treated.
As these saw-sets are adjustable, the teeth may be bent much or little
as the work to be done demands.
Second, the teeth are jointed. A flat file is run lengthwise over them
the full length of the saw so that none of the teeth may project more
than others. Fig. 40 shows a flat file in position for jointing. This
block keeps the surface of the file at right angles to the blade of the
saw.
[Illustration: FIG. 40.]
[Illustration: FIG. 41.]
Third, the saws are filed, a three-cornered file being used for this
purpose. The kind of saw determines the angle or angles at which the
file is held with reference to the saw blade. Fig. 41 illustrates the
position when filing the crosscut and Fig. 42 the rip-saw.
[Illustration: FIG. 42.]
[Illustration: FIG. 43.]
Fourth, the teeth are side jointed by laying the saw flat upon the
bench and rubbing an oil-stone over each side lightly, once. Fig. 43.
This is to even the sides of the teeth that the kerf may be smoothly
cut.