[time-nuts] Standards for units

Brooke Clarke brooke at pacific.net
Tue Apr 3 22:21:29 EDT 2007


Hi:

There was a recent incident when a passenger aircraft (maybe Canada) had 
to make an emergency landing because of a wrong metric - English 
conversion resulted in not enough fuel to get to the destination. 

Are there metric equivalents to different series of English threads.  
For example I recently purchased a tap for 8-40 threads after mistakenly 
purchasing a 6-40 tap.  Most good hardware stores in the US have 4-40 
taps, dies, various lengths screws and nuts.  Although 6-40 and 8-40 are 
standard sizes they are not commonly stocked.  Are there a a number of 
alternative combinations of root diameter and pitch in the metric system?

Have Fun,

Brooke Clarke

w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com



Magnus Danielson wrote:

>From: Hal Murray <hmurray at megapathdsl.net>
>Subject: Re: [time-nuts] Standards for units
>Date: Tue, 03 Apr 2007 17:14:50 -0700
>Message-ID: <20070404001451.A4954BE06 at ip-64-139-1-69.sjc.megapath.net>
>
>  
>
>>>The US has been metric since 1988, however the continued use of
>>>customary units during the indefinitely long transition time is the
>>>problem. Fundamentally it seems there is a lack of political will to
>>>place a  definite cutoff date on the use of customary units. 
>>>      
>>>
>>I have friends who work in the auto industry.  They reported (over 10 years 
>>ago?) that all new designs are metric.
>>
>>I wonder how much it would help if GSA gave a serious preference to things 
>>that were metric?
>>
>>What's 8.5x11 in metric?
>>    
>>
>
>An odd-shaped A4ish paper for which there is no propper envelope.
>
>This fact I had to learn from an American professor that was enligthened when
>he came to Sweden. Since then he converted to A4 even in his NYC flat where his
>wife mostly lives (there is a downside to being professors at different
>universities divided by the atlantic).
>
>  
>
>>Do we have to convert to A4 too?
>>    
>>
>
>Preferably. :)
>
>  
>
>>For real fun, look at bicycle parts.  I remember seeing one part that had 
>>25.4 threads per inch.
>>    
>>
>
>:)
>
>  
>
>>What fraction of the military is metric?  Do they buy potatoes in kilos or 
>>pounds?
>>    
>>
>
>The aviation side certainly have alot of imperial measures. Figures.
>
>Look at GPS. Certainly metric all the way as far as I have seen. Like all
>aviation stuff that part may ofcourse use a mixture. Wonder what nice orbit 
>errors they would have if they used metric and survey inches as basis.
>Hmm.... 2 ppm would be some 50 m or so.
>
>  
>
>>>One would have thought that with the advent of computers using the
>>>"survey inch" and related units for new surveys would have vanished by
>>>now. 
>>>      
>>>
>>There is probably a lot of legal baggage there.  I'll bet they will be one of 
>>the last holdouts.
>>    
>>
>
>I wonder just how many metric related laws they would have to write before
>all things is metric. There is already a few to go around you know.
>
>Cheers,
>Magnus
>
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>  
>



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