Apology to Eric Coiner RE: Diametral Pitch

[Errol Groff]

Yo the list ingeneral and Eric in particular:

You may recall a somewhat heated discussion between myself and Eric a
while back regarding the definition of the term diametral pitch. I
maintained that it is simply a ratio and non dimensional and Eric
maintained that in inch gears it is an English dimension. I wrote to
an acquaintance at the Fellows Gears Shaping Company in Vermont and
received the tollowing reply.

Nathan Ainsworth
Fellows Corp.
ncain...@fellowscorp.com

I am answering you letter of 9/1/01,since Brad has been retired for
about one year now. I have been with Fellows for 21 years as a Cutter
Design Eng. and when needed, an instructor for our Gear Theory
Seminar. Prior to Fellows, I was Math teacher in Claremont, NH school
system.

You are right and wrong. DP is a ratio or if you wish a conversion
factor ,ie. quart per gal etc.
Definition is correct, but diametral pitch is an English unit of
conversion. The metric equivalent would as you mentioned is modular.
English : 60T/6 DP = 10" pitch dia. Metric 4.2333 modular X 60T =
254 mm pitch diameter

Eng. to Metric 25.4/6 dp = 4.23333 mod.

.......if I was to attempt to cut that metric gear I would be using a
modular cutter NOT a involute cutter........

Be careful with this statement. Involute is involute whether it is
created from an (inch) English base diameter or a metric base diameter
(mm). You can used the above 6 dp cutter and you would also be cutting
a 4.2333 mod.
(metric) gear. Base dia. , pitch dia. are the same.

Hope this help a little and at the same time spur some more
conversation.

As Nathan was kind enough to take the time to reply I accept the fact
that I was in the wrong and sincerly apologize to Eric for my refusal
to accept his information as correct.

Again, apologies to Eric and to all and I will make more certain of my
facts before poppping off in the future.

Errol Groff

[Kathy and Erich Coiner]

Apology accepted.
Erich
now lets get back to the WTC saga........... :(
"Errol Groff" <errol...@snet.net> wrote in message
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