Complete the line by scribing from the other prickpunch mark in the opposite direction.Flat Steel SquareThe FLAT STEEL SQUARE is a desirable tool forconstructing perpendicular or parallel lines. In themethod of layout, known as parallel line development,the flat steel square is used to construct lines that areparallel to each other as well as perpendicular to thebase line. This procedure is shown in figure 2-2.Simply clamp the straightedge firmly to the base line.Slide the body of the square along the straightedge,and then draw perpendicular lines through the desiredpoints.Before using the flat steel square or at least atperiodic intervals, depending on usage, see that youcheck it for accuracy, as shown in figure 2-3. Whenthe square is off, your work will be offcorrespondingly no matter how careful you are.Combination SquareThe COMBINATION SQUARE can be used todraw a similar set of lines, as shown in figure 2-4. Anedge of the metal upon which you are working is usedas the base line, as shown in the figure. One edge ofthe head of the combination square is 90 degrees andthe other edge is 45 degrees. Combination squares areFigure 2-2.—Using a swuare to cinstruct perpendicular andparallel lines.Figure 2-3.—Checking a square for accuracy.Figure 2-4.—Using the combination squaredelicate instruments and are of little value if youhandle them roughly. Store your squares properlywhen you have finished using them. Keep them cleanand in tiptop shape, and you will be able to construct90-degree angles, 45-degree angles, and parallel lineswithout error.ProtractorTo construct angles other than 45 degrees or 90degrees, you will need a PROTRACTOR. Mark thevertex of the angle of your base line with a prickpunch. Set the vertex of your protractor on the markand then scribe a V at the desired angle (assume 700).Scribe the line between the vertex and the pointlocated by the V, and you have constructed an angleof 70 degrees.Prick PunchWhen you locate a point and mark it with the PRICKPUNCH, be sure to use alight tap with a small ball peenhammer, ensuring it is on the precise spot intended tomark. The smaller the mark you make (so long as it isvisible), the more accurate that mark becomes.DividersYou should use DIVIDERS to scribe arcs andcircles, to transfer measurements from a scale to yourlayout, and to transfer measurements from one part ofthe layout to another. Careful setting of the dividers isof utmost importance. When you transfer a2-2