of the box so that the 12-inch mark on the blade and the 12-inch mark on the tongue will both come FIGURES 2 AND 3 FIGURES 5 AND 4 This gives the angle of a perFigure 3 shows exactly on the edge of the box. miter cut of the intersection of the fect square, as shown in Figure 2. the manner of placing the square on the box to give the desired angle. A sprung molding, which is a molding not solid on the back, as shown in Figure 4, must be placed in the box bottom side up as shown in Figure 5, so as to get a solid bearing to hold it. Cuts in the box to miter around an eight-sided figure or an octagon, as shown in 5A, can be obtained by using 7 inches and 17 inches, marking the cut on the 7-inch side, as shown in Figure 5. TRUING THE SQUARE After obtaining a steel square, the first and most essential thing is to test or prove it to see that it is accurate, forming the angle of a perfect square. FIGURE 6 Take a board planed on one side and straighten one edge of it perfectly as described under Making a Straight Edge. Make a mark across this board with the square, as shown in Figure 6, Position A, then reverse the square to Position B. If the square is true it should exactly fit the mark made. It is necessary to work very accurately, making the mark with the point of a knife and having the edge of the board absolutely straight. If the square is found to be out or inaccurate, it is not necessary to throw it away; it can be made true by a simple method by any handy mechanic. If you do not possess an anvil, make a substitute by To Open the To Close, the FIGURE 7 sticking the ax into a chopping block, lay the square on the head of the ax so that the bearing will come from the throat or inside angle to the heel or outside of the square. To close up the angle, strike with a hammer a sharp blow at a point near the heel; to open the angle, strike near the throat at a point indicated in Figure 7. Don't strike too hard. Use a bell-face nail hammer and the dent will not be noticed. A STRAIGHT EDGE In connection with the work with the steel square a straight-edged board is necessary to have ready for immediate use. Procure a board 8 or 10 feet long of good, dry pine, free from knots and 6 to 8 inches wide. Plane the edge until it seems straight to the eye, then lay it on the bench or on another board and make a mark along the edge, just straight with a fine lead pencil; reverse it or turn it over and fit it to the other side of the pencil line. This multiplies any inaccuracy or deviation from a straight line. Make a new line each time you plane the edge. Work with as long a plane as you have and set the blade to take a fine shaving. When the edge will fit both sides of the line made from it while in one position, it is straight. Figure 8 will give a clear idea of this operation. RAFTERS The common rafter for a pitch roof is easily laid out with the steel square. There are many methods, but the easiest and most simple is by spacing. Two dimensions, half the width of the building and the height of the roof, are divided into an equal number of parts. The width of half the building is called the run and is usually divided into parts of 12 inches or a foot for convenience. The height is called the rise, and is divided into an equal number of parts. A glance at Figure 9 tells us that the run there shown is 10 inches rise to 12 inches run. FIGURE 9 When the square is laid on the stick to be cut into a rafter, the lo-inch mark on the tongue and the 12-inch mark on the blade are held so that they come exactly even with the outside edge. The blade then takes a level position and the tongue a vertical position or plumb position. This gives the proper level for the cut at the top of the rafter and |