[ARC5] A flame against the imperial system - (was cost of sets)

[Leslie Smith]

I've worked in various shops over the last 40 years.  All were metric.  On the wall beside every lathe, milling machine etc was a table that set out thread pitch definitions for various imperial threads, often SAE and Whitworth.  There was always ONE metric table - metric coarse.  Metric fine is rarely used - it's used for exotic purposes only.

There are several advantages of the metric thread system.  (1) You always deal with integer numbers, and can forget trying to figure if 23/32 is bigger or smaller than 11/16.  (2) Metric is metric - whether in Japan, France, Germany or Australia.  Metric is a standard.  There are not several versions of metric (at least so far as threads are cut.)  (3) You don't have to get out thread gauges to determine whether your thread is UNC, Whitworth, BA or whatever.  It's metric. (4) When you deal with a metric system you can get down to an accuracy of about 1/16 of an inch (39.4 mils to be precise) and still deal with an integer.  You don't have to worry about 3/16 of an inch (which is about 4.76mm).  You pick up a 5mm bar and know your 5mm die will cut a nice thread on it.  (5) Finally, I dream of living in a country where there is only ONE thread.  The American influence in Australia is pernicious.  Shops still carry imperial threads because imported American goods have imperial threads.  When whatever it is you have breaks it's necessary to figue WHICH imperial thread is being used.  I hate the imperial system for that reason more than any other.  PLUS the duplication in hardware (nuts & bolts) costs a FORTUNE.

As for whether it's easier to use horsepower (the weight an average horse could raise in one second, ie 550 foot-pounds per second) or watts, (1 joule per second or 746 watts per horsepower) THAT is a matter of what you learned.  Conversion of units is not difficult.

The ONE place where I prefer metrication is in PCB layout.  A pin spacing of 0.1 inches is a LOT more useful than 2.50mm, especially when it's a many element connector.  The Japs have bastardised the PCB system.  

Enough.  Best wishes from the theoretically metric Australia. 

Les


> ----- Original Message -----
> From: WA5CAB at cs.com
> To: Arc5 at mailman.qth.net
> Subject: Re: [ARC5] Cost of sets - 1950 and 2010
> Date: Thu, 23 Sep 2010 17:44:57 EDT
> 
> 
> Another basic flaw in all of the numerous Metric threaded fastener
> "standards" is that as a general statement, bolt/screw heads are too small and
> thread pitch is too fine relative to the diameter for use in the dirty real
> world.  OK to put together - just don't expect to be able to get 
> them apart again
> half a century later.
> 
> In a message dated 9/23/2010 4:35:07 PM Central Daylight Time,
> kgordon2006 at verizon.net writes:
> > On 23 Sep 2010 at 11:26, Henry Mei'l's wrote:
> >
> > >Europeans shake their heads about the Anglo-Saxon use of  feet, inches
> > >etc. BUT one advantage is that an inch is the rough quivalent of the
> > >top joint of your thumb, the foot ... , the yard the length of your
> > >extended arm to mid-chest, etc.
> >
> > Another advantage is that the English system has been 
> > standardized for well over a century.
> >
> > As far as I can tell, there are STILL no universally standardized 
> > metric threads and diameters. This is one reason why a metric tap 
> > and die set in the U.S. is so cheap when compared to an "English" 
> > set: the metric tap and die set only fits itself.
> >
> > I remember an Italian rapier I once worked on which had a damaged 
> > thread where a special nut held on the hilt: it was metric 
> > diameter, and turns-per-
> > inch. I cut the darned thing off and welded on a piece of 1/4-20 
> > threaded rod.
> >
> > In my opinion, from a machinists standpoint, it really doesn't 
> > matter what standard you use....as long as it IS a standard.
> >
> > Furlongs-per-fortnight would be just as good.
> >
> > Ken Gordon W7EKB
> > _
> 
> Robert & Susan Downs - Houston
> wa5cab dot com (Web Store)
> MVPA 9480
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