[AT] Supposedly why our old tractors are not metric and a fairly simple tutorial

[Cecil Bearden]

Most ball bearings are metric unless you get the special sized ones.  
they are still a metric OD even if the shaft size is SAE.
Cecil

On 2/24/2020 8:17 PM, John Hall wrote:
> Fun fact. Did you know metric pipe threads are actually in inches? 
> They are actually 55 deg threadform (British Whitworth) but the pitch 
> is in metric. And the real fun part is that the rest of the planet 
> can't even decide how to spec them on drawing/print/blueprint. 
> Different countries  have different designations for the same thing. 
> Off the top of my head, I think there are a combined 7 different ways 
> of designating metric pipe threads (taper and straight), as opposed to 
> just 2. Now we won't split hairs with short projection, dryseal or 
> other specialty threads--lets stick to 99.999% of pipe threads.
>
> FWIW, I have 30 years in a machine shop and have continually used both 
> english and metric without an issue. Its the rest of the planet that 
> makes a big ordeal out of it, we just grab a print and go with it. 
> English, German, Japanese--its all the same--until we have to use 
> Translate Google to figure out the notes.
>
> One more fun fact. Next time you need some roller bearings for your 
> old tractor and start measuring them only to find they aren't exactly 
> english, convert them to metric--you might ought to sit down first.
>
> I won't even get into European conduit threads--I've only had to do 
> them twice.
>
> John Hall
>
>
> _______________________________________________
> AT mailing list
> AT at lists.antique-tractor.com
> http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com