Metric? Is it the way to go?

[Slappy]

I learned metric and imperial in school.  Every science class was based in metric and the research lab I worked in is all metric.   

I don't think I will change over to metric when building stuff.  I can't visualize 1390mm and would have to undo a lifetime of imperial associations. I just don't think the benefits outweigh the effort to switch over for me.   

+1

 

[JeromeM]

the problem is that you are talking about today's tech and building new plant. And the 32mm system was established just after the war when existing tech and machines had to be used. The reason was because of the huge need due to the destruction caused by the war together with the lack of money and resources to build new plant. And that tech was capable of reliably and economically spacing no closer than 32mm QED

Gears haven't just been around for several decades. They have been around for many centuries. If 32 mm was a minimum achievable pre-WWII size, then that would make for a rather bulky pocket watch. Wouldn't it?  [big grin]

The module of a gear is what dictates the geometry of the teeth. Two gears of different diameter will mate as long as they have the same module. That is not a 20th century invention, nor are the mathematics anything new.

So the only difference between a 30mm gear and a 32mm gear, when both have a module of 1 (or even 2), is the number of teeth cut. Each tooth has the same shape, and that is why they will mesh. But one gear would be rotated 1/32 of a revolution per tooth (for a module of 1) while the other would be rotated 1/30 of a revolution per tooth, and of course the net diameter of the gear would be 32mm versus 30mm.

So the very same equipment that could make a 32 mm gear with a specific module (assume 1) with 32 teeth, would also make a 30 mm gear with 30 teeth (or even a 12 mm gear with 12 teeth). As long as the module of the gear stays the same, the geometry of the teeth stays the same, and the only thing that varies is the diameter and number of teeth. The ratio of those two parameters is in fact the module of the gear. That is why it is such a critical parameter in gear design.

Edit: If you look at the image below, you will see that the size, shape, and spacing of the teeth are the same. The only thing that varies is the diameter and number of teeth.

The ability to make gears of any tooth count is a given, but that is a different and unrelated fact.
Indeed all that you have said is true. But it doesn't address the detail that "the existing line boring machines available at the end of the war did not have the capability of being adjusted to less than 32mm." Why that was I have no idea, but that it was is the case and reason for 32mm standard

 

[mouppe]

I was always given to understand that it's a 32mm system and not another number because of the ease of using base 2 and its multiples.

 

[Rick Christopherson]

I was always given to understand that it's a 32mm system and not another number because of the ease of using base 2 and its multiples.

When an answer is unknown, it is not uncommon for things to get invented to fill in the holes. There is no ease in using base-2 math, especially in an era that predates the common existence of the personal computer (binary system) by a few decades.

 

[Kev]

I was always given to understand that it's a 32mm system and not another number because of the ease of using base 2 and its multiples.

When an answer is unknown, it is not uncommon for things to get invented to fill in the holes. There is no ease in using base-2 math, especially in an era that predates the common existence of the personal computer (binary system) by a few decades.

We'd be calling the 20mm system with units confusingly in hexadecimal notation [wink]

 

[Rick Christopherson]

We'd be calling the 20mm system with units confusingly in hexadecimal notation [wink]

[big grin] [big grin] [big grin] [big grin] See. There you go. Nice even number. It was supposed to be hex all along.

P.S. I did have to cheat and use an on-line decimal to hex converter  [tongue]