The EDM in "wire EDM" stands for Electric Discharge Machining. This means that metal is being removed from the workpiece electrically, or more specifically through millions of tiny sparks which jump between the wire (from the first part of the name) and the workpiece. The process creates...
Reading some of this discussion, I'd like to note that we apparently have two distinct viewpoints on this topic, since Spurs and gearguru seem to agree with my approach, while dimjim, israelkk, and gearcutter do not. First, it's important that we can all hope to learn something from...
Well, you could call this a "mathematical trick", but the mathematical truth is that the curve we know as the "involute of a circle" is really just a single curve. There is no 14.5° involute or 20° involute or whatever. It's just ONE curve on which we base all "involute form" gear teeth. If...
Go back to the typical definition of "pressure angle". It is the angle between a tangent to the involute at the "pitch circle" and a radial line through the point of tangency. A gear tooth that includes a 20° pressure angle also has a point closer to the root where the pressure ange is 14.5°...
