Homebrew PCBs

No question about it metric is here to stay and will eventually push 
out the imperial system of measures.  As for fractions, most people 
are taught the basics 1/8, 1/4, 1/2 etc. in grammer school and those 
will get most people through life as greater precision is seldom 
required in "normal" day to day life.

Woodworkers work down into the smaller fractions 1/32 and somtimes 
1/64 as they need greater precision than "normal" life.

Machinists work down into the smaller fractions 1/64 and 1/128th but 
this is only for very roughly dimensioned stuff - things you cut 
with a torch or a saw.  As you all know, machinists require much 
greater precision and thus drop down into the decimal form of 
breaking an inch into smaller units of measure.  

Typically being .0001" and this is referred to in the shop 
as "tenth".  TO confuse matters more, it is the point of view of the 
person you are talking to as to a tenth of WHAT?  A surveyor 
probably thinks in terms of a tenth as either a tenth of a mile or 
possible a tenth of an inch - depending on what he is measuring.  An 
inch is a mile to a machinists and so their basis is always the 
thousandth of an inch.  So, a tenth to a machinist is .0001" or, one 
tenth of a thousandth.

Going between fractions, decimals and metric is really easier than 
dealing with capacitor values and their units of measure :-) But 
then again, I was a machinist before I started with electronics ;-)

In the end, it is much easier to work with it all if you just 
consider it a lable for a unit of measure.  Forget it's politics, 
forget it's basis, and just accept each for what they describe.  
To me, it all looks like this....

1/32" = .03125" = .79 MM

It's all the same thing, just different ways of saying it.  Sort of 
like imepance and resistance etc.etc.etc.

Chris




--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@...> wrote:
>
> Well, you are surely right in saying you use metric/imperial as it 
makes  
> sense.
> My point is imperial make no sense whatsoever on a greater scale. 
It may  
> well make sense for you personally to use it because it is 
just "all  
> around you". But the system itself does _not_ make much sense, and 
most  
> people who are familiar in both systems say that.
> 
> A single person can't do anything either way, but the trend is 
slowly but  
> definitely going towards metric, even in the US, and even
> for components metric is used for new developments.
> 
> The entire world may not be metric. yet. ;-)
> 
> Most countries are already anyway.
> 
> ST
> 
> On Wed, 26 Apr 2006 14:45:53 +0200, Robert Hedan  
> <robert.hedan@...> wrote:
> 
> > "DEEP WRONG" is assuming everyone around the world has access to 
metric
> >
> > equipment and material.  Canada has gone metric for decades now, 
but  
> > there
> >
> > are still things that are dealt with in Imperial units.  The 
world is NOT
> >
> > metric, Europe may be metric as well as other countries, but THE 
WORLD  
> > is an
> >
> > exaggeration.
> >
> >
> > The paper I use is in letter format, 8 1/2" x 11".  Trying to 
relate  
> > metric
> >
> > measurements to the paper format is ridiculous.    All the 
components I  
> > use
> >
> > have footprints in thousands of an inch, why should I follow the 
flock  
> > for
> >
> > the mere sake of following?  I use metic where metric makes 
sense, and I  
> > use
> >
> > imperial where imperial makes sense.  Over here, using metric 
in  
> > PCB-making
> >
> > is a waste of time.
> >
>