An Analysis of Rotary Tool Geometry Recommendations

Published geometry revision recommendations are frequently in error in one or more of the following ways: 1) they do not relate relief angles to tool diameter, 2) they perpetuate the myth of harder materials needing less relief and softer materials needing more, 3) they perpetuate the myth about the superior strength of eccentrically ground end mills, 4) they use part material as the primary factor in tap selection, when hole configuration is the primary factor, and 5) they isolate certain elements for revision without regard for the complete tool geometry. The search for performance improvement through geometry variation should begin with catalog tools, since there is often a brand and style which offer superior performance in a specific application. 3 refs