Diametric Pitch

Put "Diametric Pitch" into Google (without the inverted commas ) and it insists on giving me "Diametral Pitch" and it seems Wikipedia only wants that word too. Am I having a senior moment? Using the restricted search on the home page for this forum agrees with me as does the forum spellchecker.
Did it get metricised or something? Was there an ISO naming standard I missed?

If I force it I can get some results but I just don't recall coming across this before and have a reasonable vocab. As an aside I casually used the word "alacrity" in a meeting recently and nobody else knew what it meant

You're in very good company if it's a senior moment.

The bad news is that none of my books support 'Diametric Pitch'. As far as I can tell it's been diametral at least since 1939. Time for you to go metric perhaps, there's no such confusion with 'module'.

Dave

I have BS 436: Part 1:1967 on my desk at the moment. It's 'Specification for Spur and Helical Gears... (diametral pitch series)'

So I can confirm it's been 'diametral' since at least 1967...

Regards,

Richard

Sod that, I'm not going metric. I'll go metral instead

Edited By Mark Rand on 19/06/2017 16:17:55

Metral, eh Mark Rand?

Would you use millmetrals to measure diametric pitch then? Or gunits?

Just joking.

When talking Imperial size gear teeth sizes, diametral pitch is the term used, not diametric, in North America.

When talking metric gear teeth sizes, module is used in North America. JD

.

With or without the inverted commas, and with or without capitalisation

... what you seek is only a click away:

.

.

MichaelG.

Edited By Michael Gilligan on 19/06/2017 16:37:35

Well at least that comes up with plenty of hits too so it is in common usage. Also a link to " diametrical " pitch which is also in the forum spell checker whereas diametral gets red lined.
I put diametral into the forum specific search and get 68 hits but diametric gets 127 so I think I must have picked up the term from reading Model Engineer as that anyway is how I learned 90% of my useful knowledge.

I wonder what else I'm out of step with. Perhaps I should start using 'laith' like some on ebay do.

We metric zealots must be wiseacres...

Diametral or Diametric. Does it matter? We know what you mean. Some people need to get out more

Using the word alacrity is nugatory.

Tim

It's a subtle distinction, Bazyle ... but I believe that:

• Diametral means 'based upon' or 'relating to' the diameter ... whereas
• Diametric means 'across' the diameter [in the sense of things that are diametrically opposite]

MichaelG.

.

Hectarious, Dave

MichaelG.

Then there's "diametrical" according to my OED .... but not "diametralic".

Edited By Bandersnatch on 20/06/2017 01:35:47

Diametral would seem to fit with circumfrential, radial, axial and so forth.

But both the -ic and and -al suffixes mean "relating to" so six of one and half a dozen of the other really. (Or five of one and 0.5 of a metric dozen of the other if you are that way inclined.)

.

Hopper,

I've just found this: **LINK**

http://wikidiff.com/diametral/diametric

... which I think you will appreciate.

After trying [as did I] to describe the distiction, they then list synonyms

MichaelG.

Diametral Pitch was used in BS 436: 1940 Machine Cut Gears.

I also have a copy of Machine Cut Gears from David Brown dated 1921 which refers to Diametral Pitch. The introduction in the book says that it is a reprint of their 1903 book.

I have nothing earlier, but the term seems to have been in use for a long time.

But I agree with Duncan, we all know what you mean, most of the time we just use the symbol DP and not worry what it stands for.

Neil

Edited By Neil A on 20/06/2017 14:06:43

And "diametral" according to my 1914 replica Machinery's Handbook ... any higher bids?

Oh, I see Neil A snuck in with a 1903