When greater force has to be applied to the chisel, as in paring across the grain, the handle is held in the closed right hand, the end of it standing out a little on the upper or thumb side, and the flat side of the chisel being turned towards the body. Leaning over the work and bringing the shoulder against the handle of the chisel, the tool is forced downward by the pressure of the hand and the shoulder together. In this case, also, the oblique or sliding movement makes the tool cut easier.

As an exercise in this method of using the chisel, one end of the piece used in the last exercise may be "chamfered" or "beveled" on the edge. The work must be first marked out, as in Fig. 43 which shows elevation, plan, and end elevation of the piece. The line F E is to be drawn lightly, on one end, with the gauge, in the middle of the thickness of the piece; C D is to be drawn on one face, with lead-pencil and square, at the same distance from the corner that E F is; A B may be ruled with the lead-pencil and the edge of the square. The line A B, being on the top of the piece, is visible in the plan; C D, being on the back, is dotted on the elevation, and for a like reason, E is dotted in the right-hand end elevation. Holding the piece in the left-hand, by one end, rest the edge, at the other end, on a clean piece of wood, - not on the bench. The bench may have dust on it, which would dull the chisel; and besides, chiseling on the bench destroys the smooth surface that it ought always to have. The piece should be held with the side that is to be beveled turned from you; leaning over, you will then have a good view of the part you are cutting. Setting the edge of the chisel near the corner, as at a, Fig. 44, press it down and cut off a small chip. Then setting it back a little, as at 6, cut off another, and so on. As the cuts become wider it will be harder to drive the chisel down, and you will have to take thinner shavings. Do not forget, particularly when making the last cuts, that it will work easier if, while pushing the chisel in the direction D C, you also slide it in the direction B A. The last cut should be a very light one, and made very carefully and with a keen chisel, so as to leave the surface quite plane and smooth.

Exercise 27. Chamfering End-Wood

Fig. 43.

After chamfering one side of the end A, mark and chamfer the other side of the same end, working the end to a sharp edge. Then chamfer the other two edges of the same end, working it to a point. As the quantity of wood to be removed in this part of the exercise is less, the chisel will work easier, and the pressure of the shoulder will not be needed. You may hold the piece in your vise, the end that is to be beveled projecting only a little above the bench, so as to be firm, and the chisel being managed as in Exercise 25. Finally, make a drawing in plan, elevation, and end elevation of the finished piece, to a scale of 1/2.

Fig. 44.

3. In the exercise just finished, the cut was made obliquely across the grain. When it is made square across it is more difficult. In this case, and particularly when the piece to be cut off is so situated that the sliding movement cannot well be used, a mallet is used to drive the chisel. In this is case the chisel is held in the left hand, nearly or quite perpendicular to the surface of the wood, and with the same grip as in the last exercise, but not bearing against the shoulder. The hammer must not be used instead of the mallet, as this will deface the handle of the chisel, and after a while split it. When the position of the cut will allow it, some of the wood may be removed by the brace and bit, or a portion of the cut may be made with the saw, before beginning to use the chisel. The next exercise, a "through-mortise," will illustrate the first plan, and the following exercise, an "end dove-tail," the second.

Figure 45 is a working sketch of one form of a "mortise and tenon" joint. A and B are elevation and plan of the mortise and C and D of the tenon. No end elevations are needed.

Exercise 28. Mortising

The dimensions are given in centimeters, that is, hundredths of a meter, that the eye may become accustomed to Metric measures as well as English measures. A centimeter is a little less than half an inch (0in.39), a meter being a little more than a yard (39 inches, or 3.28 feet). An examination of the drawing will show that, when the two pieces E and F are cut out, the remaining piece, or " tenon," will, if properly cut, fit closely in the hole or mortise G, and the pieces will be firmly joined together perpendicular to each other.

To make this joint, the pieces must first be planed up exactly square and to the true dimensions. Sharpen the plane if necessary. First plane one surface of each piece true and mark it thus x. Next plane one adjacent surface on each piece true, and perpendicular to the first surface, testing with the square. Next, mark the pieces to the proper breadth and thickness with the gauge, measuring from these finished surfaces, and plane to the marks. All four surfaces of each piece should now be of the proper dimensions, and the pieces square, Set the smoothingplane fine and finish the surfaces, taking off only enough wood to make the surfaces smooth.

Now mark out the joint, drawing the lines a, b, c, d with the gauge, being careful not to mark them too deep nor to extend them too far, and draw the other lines with the square and a sharp lead-pencil. Both sides of the pieces must be marked, and also the end of the tenon-piece, C D.

To cut out the wood from the mortise, first use the brace, with a center-bit three or four millimeters smaller than the width of the mortise (a millimeter is a tenth of a centimeter, or a thousandth of a meter, and is the smallest division on your metric rule).

Notice the way in which the center-bit works. The revolving knife-point or "cutter" first makes a circular cut, and then the revolving chisel, following the knife, removes a chip. If the cutter is not sharp on the front edge it will not make a clean cut.

Exercise 29. Boring With Center-Bit

If it is too short, the chisel will cut before the cutter has prepared the way for it, and will tear out the wood beyond the intended circle. Hence, though the cutter must be sharpened with a file when necessary, the sharpening must be done only on the inside edge, and very carefully, for if the outside edge is filed the circle cut will be too small, and if the cutter is made too short the bit is spoiled.

With the center-bit a hole is to be bored through the piece near each end of the mortise. It is necessary that this hole should go through quite squarely, or it will cut away wood which ought not to be cut. A few experiments may be made first on the other end of the piece, or on a piece of waste wood. Mark a point near the end, as at P, Fig. 46, and then with the gauge and square find the point exactly opposite P. Hold the piece in the vise, the end P standing up above the bench. Place the handle of the brace against the breast, set the point of the bit on P, hold the bit perpendicular to the surface, and begin to bore without altering the position of the brace. No hard pressure on the brace will be needed, if the wood is soft, as pine or white-wood, and the bit in order. When you have bored about lcm, stand aside, holding the end of the brace in the hand without altering its position, and examine, both from above and from the side, whether it is perpendicular to the surface of the block. If it is not, make it so and go on. Examine again once or twice before boring through. As soon as the point of the bit begins to show, if it comes out at the marked point, or within one or two millimeters, you have bored pretty well and may venture to bore the holes for the mortise. As soon as the point makes its appearance reverse the block and bore from the other side, or clamp another piece tightly against your piece in the vise, and bore through against that. Unless you take one or the other of these precautions the bit will splinter the wood when it comes through. The first two holes having been bored, as in the Figure, a series of holes may be made between them, touching each other, and removing most of the wood from the mortise.

Fig. 46.

The mortise is now to be trimmed to its exact size and shape with the chisel. To do this, lay the block on a piece of clean wood on the bench, set the chisel (which must be a little narrower than the mortise) upright on it about 1/8 inch inside of the end mark, the flat side towards the mark, and drive it in by a smart stroke of the mallet. Pare away the wood at the sides of the mortise with a wide chisel; drive the narrow chisel in again, and so on till the mortise is cut about half-way through. Then turn the piece over and cut in the same way from the other side. A little wood has been left, which is now to be very carefully pared off, holding the chisel against the shoulder as explained in the previous lesson, and taking especial pains not to cut beyond the marks. This paring also should be continued half-way through from opposite sides in succession. The four sides of the mortise, if properly finished, will now be smooth, perpendicular to the faces, and parallel, in pairs, to each other.

The tenon is to be cut with the "back-saw." This is, as you have seen, finer than the cross-cut-saw heretofore used, and if skillfully handled will leave the surfaces smooth enough without the use of the chisel. To avoid the risk, however, of cutting the tenon too small, it will be best, until you have acquired considerable skill, to saw not quite up to the marks, leaving a very small amount to be pared off with the chisel.1

If the mortise and tenon have been properly cut, they will now fit closely together. The tenon must not go in too tight. If it does, particularly sideways, it will split the mortise-piece. If it does not enter when driven with gentle blows of the mallet, it must be withdrawn. The bruises on the surfaces will show where it fits too tight, and either it or the mortise must be pared down carefully till a good fit is obtained.

1 Some particulars in the management of this saw when cutting lengthwise of the grain are given in the next lesson (page 115), and may be noticed here.