Cutting Tool Head Shapes
Generally speaking, the more metal there is on the cutting end of a precision cutting tool the longer the life of the tool. Oval head tools, with a lot of metal in the head, are best able to handle the repeated shock of the cutting load. To increase tool access to the work piece, metal is removed to produce a tapered head and tapered relieved head designs. It is like sharpening the point of the tool. But there is a tradeoff. As a tool head becomes more pointed it loses strength and may fail sooner.