Having prepared Harry for the serious work to come by his explanation of the plane and its operation, Ralph prepared to start his pupil on the most important and difficult problem in shopwork—squaring up stock.

"Anybody," he said "can hack away at a piece of wood with tools, and get some kind of result, but if this work is worth doing at all, it is worth doing well, and to be able to square up stock is perhaps the most important operation you will ever do. It is like mathematics, the answer is either right or wrong. When you finish, the stock is either square or not square.

"To square up stock means to reduce it to three definite dimensions, length, breadth, and thickness, with all adjoining edges or surfaces at right angles. It sounds easy.

"Suppose we want a piece 12 inches × 2 inches × ⁷/₈ inch. First, saw out your stock about 12¹/₄ inches × 2¹/₄ inches × 1 inch. This allows something each way for the tools to remove in the process—for sawdust and shavings. It is considerably more than necessary, but on the first trial you waste more than later, when you have become skilled in this work.

"Second. Dress down one of the flat faces with the jack plane; follow with the smoothing plane and test, with straight edge, with the grain, across it, and diagonally across corners. When this face is finished it constitutes the foundation of the process, and is called the 'working face.'

"Third. Make a pencil mark on the working face near one of the edges. This is called a witness mark, and it indicates that the edge it touches is to be the next face dressed.

"Fourth. Dress down the edge, making it square with the working face, and testing its whole length with the try square. This is the 'joint edge' (Fig. 116).

"Fifth. Set the marking gauge, as shown in Fig. 117, holding it in the left hand and the rule in the right, to two inches, the width of the finished piece. The reason for this is that the scale on the gauge stick is sometimes inaccurate.

"With the gauge block against the joint edge, gauge a line the entire length of the working face. In doing this, the gauge may be used in either hand, and in fact it is well to practise so as to be able to use either at will. The tool should always be pushed from you, and at the same time tilted from you, until the steel point makes only a fine line. If it is held upright, the point will try to follow the grain, which is very seldom parallel with the edge.

"You have now laid out on the working face your first dimension—the width.

"Sixth. Plane down the edge opposite to the joint edge, almost to the gauge line just drawn. Remember that the tendency is always to take off too much, and when a piece is too small there is no way of making it larger, but if it is left a little too large, it is a simple matter to take off one more shaving. In other words, always be on the safe side, and take off too little rather than too much. Test this edge to see that it is square with working face before reaching the gauge line. Get into the habit of marking all high spots with a pencil, and planing out the marks.

"Seventh. Set the gauge at the required thickness, in this case ⁷/₈ inch—and with gauge block against working face, make a line full length on both of the squared edges.

"Eighth. Dress down the remaining rough face to or near both gauge lines just drawn, and test with straight edge, as in the working face. The stock is now to the second dimension—thickness.

"Ninth. Secure the last dimension—length. As near one end as possible make a line across the working face with a knife and try square, and continue it around the four sides back to the starting place. If it does not come out exactly at this point, the stock is not square.

"From this knife line, measure off the length on the working face, and square a knife line on the four sides, as on the first end. Block-plane both ends to the knife lines, and test.

"If these nine successive steps are carried out accurately, the answer is correct," as Ralph remarked after Harry had worked faithfully throughout the whole explanation.

The boys realized that they needed a shooting board as a necessary part of their equipment, and after Ralph had worked out the drawing shown in Fig. 118, Harry was told to square up the four pieces of stock to be used in its construction.

"Now let me show you a new trick," said Ralph. "It is always a good plan after making a drawing to write out a bill of material something like this:

"There you have in a nutshell all the items needed for the shooting board, and you can proceed to square all your pieces to these dimensions without consulting the drawing until you are ready to assemble the parts. The five ³/₄-inch screws are for fastening the maple pieces to the flat piece of pine, and the 1¹/₄ screws to fasten the cleats. All the holes for screws are to be bored and countersunk."

"What's countersunk?" asked Harry.

This led to a talk on screws and boring tools, and as it is valuable to the young worker in wood, we will give it as fully as possible.

"There are several kinds of screws," began Ralph, "but the two most commonly used are flat heads and round heads. (Fig. 119). Flat-head screws are those we generally think of, but unless the hole which has been bored or drilled is reamed out at the top, countersunk as we call it, the screw head will stand out from the surface ready to tear your clothes and to scratch anything it may come in contact with, so you can readily see the importance of sinking them below the surface.

"On the other hand, there are often cases where we have no desire to hide the screw. The round heads are used for such cases, and because of their shape they do not catch hold of things. These screws are usually blued—treated with acid to give them a dull, more artistic colour. Screws treated in this way do not rust as readily as the bright ones. You can buy brass screws in both flat and round head forms; in fact you can get tinned, Japanned, lacquered, bronzed, copper, nickel, and even silver plated screws—if you have the money.

"In buying them, you must always give two numbers—the length, in inches, and the diameter. This is the diameter of the wire forming the body and runs from 0 to 30, number 0 being about ¹/₁₆ inch.

"A one-inch screw No. 8 would be fatter or larger in diameter than a one-inch No. 6, which is of comparatively slight or thin proportions. They are sold in boxes containing a gross.

"In fastening two pieces of wood together, they should be prepared as shown at a (Fig. 119) for a flat head and as at b for a round head. The screw slips through the first board, and the screw threads engage only in the second in each case."