SQUARE files are tapered on all four sides and are used to enlarge rectangular-shaped holes and slots. ROUND files serve the same purpose for round openings. Small round files are often called “rattail” tiles. The HALF ROUND file is a general-purpose tool. The rounded side is used for curved surfaces, and the flat face on flat surfaces. When you file an inside curve, use a round or half-round file whose curve most nearly matches the curve of the work. Kits of small files, often called “swiss pattern” or “jewelers’” files, are used to fit parts of delicate mechanisms and for filing work on instruments. Handle these small files carefully because they break easily. Filing Operations Using a file is an operation that is nearly indispensable when working with metal. You may be crossfiling, drawfiling, using a file card, or even polishing metal. Let’s examine these operations. When you have finished using a file, it may be necessary to use an abrasive cloth or paper to finish the product. Whether this is necessary depends on how fine a finish you want on the work. CROSSFILING. –Figure 1-30, view A, shows a piece of mild steel being crossfiled. This means that the tile is being moved across the surface of the work in approximately a crosswise direction. For best results, keep your feet spread apart to steady yourself as you file with slow, full-length, steady strokes. The file cuts as you push it – ease up on the return stroke to keep from dulling the teeth. Keep your file clean. View B shows the alternate positions of the file when an exceptionally flat surface is required. Using either position first, file across the entire length of the stock. Then, using the other position, file across the entire length of the stock again. Because the teeth of the file pass over the surface of the stock from two directions, the high spots and low spots will readily be visible after filing in both positions. Continue filing first in one position or direction and then the other until the surface has been filed flat. Test the flatness with a straightedge or with prussian blue and a surface plate. DRAWFILING. –Drawfiling produces a finer surface finish and usually a flatter surface than crossfiling. Small parts, as shown in view C, are best held in a vise. Hold the file as shown in the figure; notice that the arrow indicates that the cutting stroke is away from you when the handle of the file is held in the right hand. If the handle is held in the left hand, the cutting stroke will be toward you. Lift the file away from the surface of the work on the return stroke. When drawfiling will no longer improve the surface texture, wrap a piece of abrasive cloth around the file and polish the surface as shown in figure 1-31, view A. USE OF FILE CARD. — As you file, the teeth of the file may “clog up” with some of the metal filings and scratch your work.    This condition is known as PINNING. You can prevent pinning by keeping the file teeth clean. Rubbing chalk between the teeth will help prevent pinning, too, but the best method is to clean the file frequently with a FILE CARD or brush. A file card (fig. 1-32) has fine wire bristles. Brush with a pulling motion, holding the card parallel to the rows of teeth. Always keep the file clean, whether you’re filing mild steel or other metals. Use chalk liberally when filing nonferrous metals. FILING ROUND-METAL STOCK. –Figure 1-30, view D, shows that as a file is passed over the surface of round work, its angle with the work is changed. This results in a rocking motion of the file as it passes over the work. This rocking motion permits all the teeth on the tile to make contact and cut as they pass over the work’s surface, thus tending to keep the file much cleaner and thereby doing better work. P O L I S H I N G  A  F L A T - M E T A L SURFACE. –When polishing a flat metal surface, first draw tile the surface as shown in figure 1-30, view C. Then, when the best possible drawfiled surface has been obtained, proceed with abrasive cloth, often called emery cloth. Select a grade of cloth suited to the drawfiling. If the drawfiling was well done, only a tine cloth will be needed to do the polishing. If your cloth is in a roll and if the job you are polishing is the size that would be held in a vise, tear off a 6- or 8-inch length of the 1- or 2-inch width. If 1-19