Drill points are used for boring small holes in wood, iron, brass, or other materials. There are three kinds of drills; flat, straight-fluted, and twist drills (Fig. 134). The flat drill can be used for almost any material, but does not cut so rapidly as either of the others. It is best suited for use on thin metals and on tile. The straight-fluted drill can be used advantageously on wood and the softer metals. It is especially satisfactory for drilling holes all the way through a piece of material, as it does not have a tendency to "draw in" when breaking the hole through. The twist drill is the most rapid cutter of the three, and is especially desirable for work on very hard woods or heavy metals, and for work where a deep hole is to be drilled. The twist drill, besides presenting a cutting edge at the point, carries the chips up to the surface, and thus prevents clogging. It is, therefore, unnecessary to remove a twist drill from the hole to clear it of chips.
Fig. 133. - A Scraper.
(Copyrighted by Millers Falls Co.)
Fig. 134. - Drill Points.