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

[John Hall]

Don't know why they couldn't change pipe threads, after all the rest of 
the planet uses 60 deg, not 55 for the British threads. Can't really see 
how it is simpler than what we use. I mean how exactly do the Japanese 
explain such? Never seen a German print in inches either for that 
matter. If metric is so much better, then go all in I say.

You missed the part about leaving out the bastard pipe threads, didn't 
you? We did so much hydraulic work at one point that all I stocked was 
NPTF, it works for NPT.  As you know, NPT covers the vast majority, 
while NPTF will cover the majority of whats left. The scraps can be left 
to those who specialize in oddities.

Never needed an IH bearing that I couldn't source from wherever. The 
only roller bearing I ever needed that was manufacture specific was the 
plunger bearing on a New Holland baler. Motion industries finally was 
able to cross it, but I couldn't find it any where else, not even 
aftermarket ag parts. And the bearing housing had to come from New 
Holland, nothing even close. That set up cost me close to $300

We have an entire section of bastard taps at work, it has just as many 
oddball metrics as it does english. It all depends on the industries you 
support as to what is in your tool crib.

I've found that engineers don't always make stuff weird so you have to 
buy from them, its often so you don't make a substitution that 
compromises the design. But there are some that need a plate glass 
stomach.....

John

On 2/24/2020 10:41 PM, Thomas Martin wrote:
>> On 25 February 2020 at 15:17 John Hall <jtchall at nc.rr.com> 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
>>
> Well, John
> Europe did adopt BSP (British Standard Pipe) threads
> back in the 19th century, difficult to change horses now.
> Quite a simple setup compared to the American system!
> Did you know that the US has 11 diffent derivatives of
> National Pipe threads?
> As for 11-1/2 tpi NPT, I bet many a lathe manufacturer
> swore when Norton invented the quick change gearbox for
> lathes and provision had to be made for that.
> In fact would say I have cut more peculiar threads of US
> origin that elsewhere.
> That goes for bearings also. Both Caterpillar and IH used to
> get bearings, especially taper-roller, ground to  their
> specific sizes, so that only they could supply, at a cost
> 5 to 10 times the cost of a standard size! Extortionate!
> Competition finally forced them into standardization in the finish.
> FMC was another who engaged in the practice in another field.
>
> Tom
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