Posted by Brian Dengel on November 20, 2000 at 12:23:19:
In Reply to: Involute Gear Geometry Calculations posted by Michael Paul on November 18, 2000 at 18:39:28:
The involute form is defined by the curve that is traced by a point on a taut cord as it is unwound from a circle. The circle from which the cord is unwound is known as the BASE CIRCLE. The involute is a form of a sprial, the curvature of which becomes straighter as it is drawn from the BASE CIRCLE and eventually becomes a straight line, if drawn far enough. The formula for BASE CIRCLE is (module) x (number of teeth) x (cosine of the pressure angle).
There are several companies that sell software that that will plot the involute form for you. Unfortunately these typically run in the hundreds of dollars.