AN EVALUATION OF THE SPIRAL POINT DRILL GEOMETRY.
ARMY WEAPONS COMMAND ROCK ISLAND ILL RESEARCH AND ENGINEERING DIV
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The spiral point drill geometry was evaluated in comparison with the conventional chisel point drill grind with respect to drill life and hole quality. Drills of 14, 12 and 34 inch diameter were used to produce one inch deep holes in FS 4140 steel quenched and tempered to Rockwell C 32 plus or minus 2. The spiral point drills, when sufficient provision was made for chip ejection, had greater life, and produced straighter, more concentric holes than chisel point drills. The successful use of the spiral point geometry required high quality drills produced to close tolerances. The preparation of the spiral point grind is more time consuming. In some cases where hole tolerances and finish requirements are not close, but are beyond the capabilities of the chisel point drill, the spiral point drill can be used to advantage to eliminate spot drilling or the use of guide bushings. Author
- Machinery and Tools