Showing how little progress has been made in tool construction. In this
collection is a jointer plane, a smooth plane, rabbit plane, straight
edge, dividers or compasses, a bench vise, hand vise, wrench, hacksaw
and combination tool.]
The proper position for planing is with the right side to the bench,
the plane held flat on the work. Each stroke should, wherever possible,
be the full length of the board, unless one part is higher than the
rest of the surface. This may be ascertained by using the edge of the
plane as a straight edge. High spots should be marked with a pencil,
and then planed off, till the full length strokes can be made, and the
edge planed straight and true. In surface planing, if the surface be
warped, the amount of wind may be determined by placing two "winding"
sticks--two straight pieces of the same size at the two ends--and
sighting with the eye along their top edges. To take out wind, it
may be necessary to plane diagonally across the grain from corner to
corner. This defect is common in lumber not properly piled or seasoned,
and is more noticeable in such woods as gum or chestnut.
The sharpening of plane irons is a very important part of one's
knowledge of tool work, and of course applies to chisels, gouges, and
all cutting tools.
Remember that the cutting edge or bevel is a wedge, the angle of a
plane-iron bevel being from 25 to 35 degrees, the smaller angle for
soft wood, the larger for hard. This angle is not measured by the
woodworker often, but is a matter of experience. If the young mechanic
will keep his tools ground to the same angle as he finds them at the
time of purchase, he will not go far astray.
[Illustration: Fig. 112. The cutting angle]
This angle should be a clean-cut one, however. Fig. 112 shows some
correct and some incorrect ways of grinding. At _a_ is shown the
right way, _b_ is not an angle at all, and _c_ is a waste of time and
material. At _d_ is shown the worst fault of all--a "back bevel."
This occurs when the tool is carelessly turned over and ground on
both sides, which renders it useless until all the steel in front of
the dotted line has been removed; in other words, until the tool is
reground.
This mistake is sometimes made in using the oilstone, by rubbing
the tool on both sides instead of on one only. All the grinding and
sharpening must be done on the bevelled side. As the plane iron is only
a thin chisel, the sharpening of the latter tool is performed as in the
case of the plane iron, and the same care should be taken to keep the
bevel clean cut.
A good grindstone is a shop necessity, and, one might add, a household
necessity, because every household uses knives, and the dull knife is
an altogether too common nuisance.
Our boys hung up another sign at this stage, and it read, "Keep your
tools sharp." This ought to go without saying, but it is a fact that
many people make failures of their work and become disgusted with it
because they do not keep their tools in order. The satisfaction of
using fine, sharp tools cannot be explained; it must be experienced.
Like other things about the shop, there are many kinds of grindstones
on the market. The old-fashioned stone with a wooden frame (Fig. 113)
worked by hand or a treadle may be good--it depends on the stone--and
the new one with a small stone, iron, or pressed steel frame is handy.
The last stone is provided with a bicycle seat, and is worked by both
feet, so that the hands are free to hold the tool. This stone has ball
bearings, is noiseless, and occupies less space than the other.
A stone that is soft and gritty, rather than one that is hard like a
piece of granite, should be selected.
In holding the tool against the stone, some common sense is necessary.
The harder one presses, the quicker the grinding, but if there is not
plenty of water on the stone, the tool may be "burned." When a black
place appears, you have destroyed the temper, showing that there has
been too much pressure, or too little water, or both.
[Illustration: Fig. 113. Two types of grindstone]
The tool may be moved back and forth across the stone to keep its face
true, but never up and down. This up and down motion is careless and
gives the defective edge shown at _b_ (Fig. 112)--very bad grinding.
It is an easy matter to test your grinding by occasionally placing
the blade of a try square on the bevel. If it is not straight, your
grinding needs more care. Too much stress cannot be laid on the
importance of this subject of grinding. It is the key-note of success.
If you are careless in this particular, your work at the bench cannot
be a success. "A good workman is known by his tools."
[Illustration: Fig. 114. The oilstone]
A teacher of drawing once said, "I don't care to see your drawing; all
I want is to see your pencil. I can tell just what kind of work you are
doing by observing the care you give your pencil."
This is peculiarly true of the worker with tools. Find a man very
particular about them, and you may be sure he is a careful workman.
After grinding comes sharpening. This is done by rubbing the bevelled
side back and forth a few times on an oilstone, lubricated with a few
drops of sperm or light machine oil.
[Illustration: Fig. 115. The action of the cap iron]
The stone should be wiped off, afterward, and should never be saturated
with the oil. If this is allowed to happen, the surface becomes gummed
(Fig. 114) and loses its cutting edge. This rubbing will sometimes turn
over a thin wire edge, which is removed by laying the tool with the
flat side on the oilstone and drawing it toward you. The wire edge can
be further removed if necessary by stropping on a piece of leather.
Before replacing the cutter in the plane, the cap iron is fastened on
the flat side about 1/16-inch from the cutting edge; but this distance
may be varied for different woods.
The object of the cap iron is to prevent a splitting action by bending
the shaving forward, as shown in Fig. 115. At _a_ is shown the effect
when there is no cap, and at _b_ the splinter bent over giving a
shaving.