[Illustration: FIG. 60.]
When two pieces of timber of equal thickness cross each other and the
joint is to be flush, i. e., the pieces when joined are to form a
flat surface, they are halved together; or, to put it in another way,
a piece is taken out of each half its thickness and as broad as the
piece which is to cross it, thus allowing the one to drop into the
other, as shown in Fig. 60. The working drawing is shown in Fig. 61.
To make this piece of work, refer to methods and operations given for
the preparation of material in the first exercise.
[Illustration: FIG. 61.]
Special results are sought for by specific methods in this exercise.
Exercises that are not finished (by the methods given) as they should
be, are thrown out as not coming up to the requirements and fall short
of the object for which they are designed.
The drawing shows two pieces of wood of given dimensions crossing
each other at right angles and halved together, making a flush
joint. _Requirements_: The pieces to be of the exact length, breadth,
and thickness called for, fitted closely on both sides, each piece
to be exactly in the center of the other, and both sides smoothed
off and perfectly flat when finished; the ends of the pieces to be
planed square, and the ends of the halving to be fitted from the saw.
_Methods_: After sawing out a piece (long enough to make both pieces,
allowing for work on the ends), plane the piece by the methods given
for planing in the first exercise; then saw it across in the center and
proceed to lay out the pieces so that the face side of each piece will
come on the same side; this means that the halving is cut out of the
face of one piece and the back of the other (see Fig. 60).
[Illustration: FIG. 62.]
It will be well to consider this problem of laying out work as a
problem in arithmetic. The pieces called for in the drawing are 5½
inches long, 1½ inches wide, and 1 inch thick. The piece that crosses
comes exactly in the center. Therefore we have a problem like this:
5½″ -1½″ = 4″, which is the difference between the length of one piece
and the breadth of the other; but the piece comes in the center, and
so we take the difference of the length, which is 4″, and divide it
by 2. 4″/2 = 2″, which will give the distance from the end up to the
first edge of the cross-piece. As all measurements have a beginning
somewhere, we mark a line near the end of the piece as shown in Fig.
62, and from this line we lay off the distance to the cross-piece,
marking with a knife point the position of the edge. Then we lay off
the width of the cross-piece, which is 1½″, leaving the distance to the
other end 2″, the same as at the first end.
[Illustration: FIG. 63.]
Having found the position of the edges of the cross-piece, we mark a
line across the work (using a knife and a square); then mark the lines
down the edges. Now taking the gauge, we gauge from the _face side of
each piece_ the depth required. Then we cut a notch _inside the lines_
with a knife, as shown at Fig. 53, place the piece on the bench hook,
saw down to the gauge lines with the back-saw (position shown in Fig.
54), and remove the portions to be taken out by the methods given for
the notch in the first exercise.
Then plane the ends of each piece perfectly square to the face side and
face edge.
An exercise that was made by a careful student and one that was made by
a careless student are shown at Fig. 63, revealing the final results of
careful as against careless work.
Having cut out the center pieces and finished the ends we fit them
together, seeing that the surfaces come flush; then smooth off the
surfaces, being careful not to cut too much off the ends, for this will
round the surfaces and thus spoil the work. Sharp tools are essential
to good work.
Lines drawn in their proper places, and then cut to, will give the
results sought for in fitting.