View Full Version : Bevel gears and diametral pitch - a question

12-30-2012, 04:56 PM
Is the term "diametral pitch" or simply "pitch" applicable to bevel or miter gears? Since the tooth profile changes from one end of the tooth to the other where would one measure the DP? big end, small end or on the pitch line?
Joe B

John Stevenson
12-30-2012, 05:45 PM
Still DP and measured at the larger end.

12-30-2012, 05:47 PM
Yes - it is applicable at the "big" end of the gear/s.

Theoretically everything tapers to a point - as it would in a 3-dimensional perspective drawing/image.

There are a few "fudges" needed to simulate/emulate the "tapering" but it is best done on a tilted dividing head but can be done (but not as well) on a verttical mill and a rotary table.

The issue is well discussed in:

"Gear Cutting" - Ivan Laws and

"Machinery's Hand Book" - Industrial Press.

J Tiers posted a very good thread on just this issue some time ago. Perhaps he (or some one else) can post the link to that thread.

12-30-2012, 05:52 PM
DP at the other, theoretical, end is infinity. Not helpful for sums. Of course teeth are never cut to that point.

12-30-2012, 05:57 PM
Thank you gentlemen. The big end it is, and that makes sense.
Joe B
PS, it never fails to amaze me, wow! I get responses from opposite ends of the globe.