# I don't get it, why is metric better?

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• posted on August 5, 2016, 9:16 pm
So the argument gos on and on, metric or imperial, which is better?
More and more I have been paying attention to metric measurements and wonder how it is better. It appears to have some short comings.
I first started seeing this on full extension slide schematics. Almost all hole locations are on fractions of a mm.
For example hole locations are located a distant of 4.4mm, 4.6 mm, 6.4 mm, 34.3mm and so on. And then the width of the whole thing is 1/2".
Could those holes not be at 4,6,or 34mm??? Why the fractions of a mm. Can you actually measure or see markings on a rule that are at 10ths of a mm? FWIW a tenth of a mm is slightly under 4 thousands of an inch. There would be 100 marks in a centimeter.
Now you might say that is an odd case but take Leigh Jigs DT instructions to upgrade. Drill hole at 4.37mm, WHAT? And drill the hole diameter at 3.57mm. Seriously, has any one ever seen a drill diameter of 3.57mm?
And then there are threaded inserts to accept 5/16" coarse thread bolts. Drill pilot hole with 11mm diameter bit. In so much that you want to work with imperial sized bolts, couldn't they have just said drill pilot hole at 7/16"?

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• posted on August 5, 2016, 9:33 pm

This argument usually appears from people who are confused about the difference between metric/imperial and the difference between decimal/fractional.
There is no "better" between decimal and fractional. Which to use depends on the task at hand. The way nature works it is often convenient to divide things by halves. But when great precision is needed, decimal is clearly the way to go.
As for the actual metric/imperial question, clearly imperial is better, since it's units are based on the physical world, not on abstract reasoning that gives inconveniently proportioned units.
Along those lines, I am always amused by people who point out the sequence of metric subdivisions by 10, apparently totally unware that almost none of them are used. Take length - the two metric units of length are mm and km. Very rarely will you find something in meters (it's more likely to be 1000mm), even more rarely will you find something in cm. The same applies the other metric units, one or two prefixs will be used, and the remainder totally ignored.
(and don't get me started on the mangled mixture of metric and imperial units used in China...)
John

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• posted on August 5, 2016, 10:25 pm
On 8/5/2016 3:33 PM, John McCoy wrote:

Really? The foot used to be just that - the length of one's foot - until it was standardised.Graham

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• posted on August 5, 2016, 10:25 pm
On 08/05/2016 4:33 PM, John McCoy wrote:

...

...
Well, not hardly...we're just getting started with one where there'll be 100, 200, 400, 800 m events just to name only a few... :)
While not totally ubiquitous, certainly the other units are reasonably common in every-day usage; it's scientific and to a lesser degree, engineering where the "power of 3" rule is prevalent, not everyday use.
--

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• posted on August 6, 2016, 2:32 am
On 8/5/2016 4:33 PM, John McCoy wrote:

Actually I believe the biggest problem with the metric system is that meter is used in every instance of resolution. Micrometer, millimeter, centimeter, decimeter, meter , kilometer.....
How often do you suppose Bob yells, cut that piece of cable to 10 centimeters and it gets cut at 10 millimeters or decimeters?
Now one might suggest that they do away with any resolution more coarse than millimeters to cut down on confusion. Bob yells, cut that piece of cable to 19,800 mm's and I also need 4 cut at 1,980 mm's.
Remember the space craft that crash into one of the moons/planets several years ago? It was blamed on a conversion error. I bet their calculation from "x" miles to "x" kilometers ended up being converted to "x" meters. :~)

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• posted on August 6, 2016, 10:14 am
On 8/5/2016 8:32 PM, Leon wrote:

Since 10 centimeters is just under 4 inches and a 10 mm length of cable would be just over 3/8", I suppose that would never happen - who would ever cut a 3/8" length of cable, or a 4" cable for that matter?

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• posted on August 6, 2016, 12:12 pm

The other possibility was about 40 inches.

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• posted on August 6, 2016, 12:12 pm
On 08/05/2016 10:32 PM, Leon wrote:

That is the beauty of the metric system, every thing is based on the meter.
You mentioned Micrometers, millimeters, etc. but for got the nanometers, picometers, Femtometers, etc.
Metric ton 1000 kilograms. If I do something on a small scale and it produces 1 kilogram. I know if I scale it up by a factor of 1000, then it will produce a metric ton.
If the English system would you give some one an 8' length of lumber if he asked for one 8" long. 8 yards for the 8'piece. Works the same in the metric system
If Bob wants a piece of cable 10 centimeters long, and the person who is cutting the pieces cuts it to 10 decimeters, ,or 10 millimeters he should be fired as the pieces would be much to short, when he can see the length that is need fits the centimeter range rather than the other two.

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• posted on August 6, 2016, 12:23 pm

But inches, feet, yards, or miles do not sound the same.
Suppose imperial was simply sillinches, billinches, centinches?

Well what makes you think 10 decimeter would be too short? The cutter and Bob are "union" workers. The cutter is not paid to think, he is paid to do what he thinks his boss said and to make the cut precisely.

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• posted on August 6, 2016, 4:58 pm
wrote:

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• posted on August 6, 2016, 2:22 pm

See, there's an excellent example. The only metric weight units in actual use are grams and kilograms (and mg/ug in science and medicine). By rights big weights should be in megagrams. But they're not, everything bigger than a kg is still measured in kg. The "metric tonne" is just a slang term, which came into popularity because it's essentially the same as a traditional ton of 2240 lbs. Since ton=tonne everyone immediately knew what weight was being talked about.
(doesn't work for Americans, of course, since they're stuck with the short ton of 2000lbs, but ton=tonne works for everyone else).
John

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• posted on August 6, 2016, 6:16 pm
On Saturday, August 6, 2016 at 5:12:22 AM UTC-7, keith snipped-for-privacy@sbcglobal.net wrote:

That's a weak argument, of course; anyone with a slide rule can lay out any ratio he wants, and read the scale straightaway for a factor of 683, 880, 1000... whatever

That's the strong argument: changing units from inch to foot, foot to yard, yard to fathom, fathom to nautical mile, nautical mile to statute mile... is annoying.

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• posted on August 6, 2016, 9:57 pm
wrote:

For woodworking, I use the inch (except when fooling with Festools). 6' 2-5/8" is much easier thought of as 74-5/8".

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• posted on August 6, 2016, 2:40 pm

That's probably why, in the real world (and Olympics games excepted :-) ) pretty much everything is measured in mm and km. Hard to get those two crossed up. Altho I do find it amusing to see something specified as being 23400 mm long.
John

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• posted on August 6, 2016, 10:03 pm
On Sat, 6 Aug 2016 14:40:30 -0000 (UTC), John McCoy

Not true. Meteorology uses the meter quite extensively. Electronics uses the micron, and medicine still uses the centimeter.

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• posted on August 7, 2016, 1:44 pm
snipped-for-privacy@attt.bizz wrote in

Well, you can find an exception for everything. Heck, aviation still does altitude in feet, and you'd have thought they'd go metric a long time ago.

True, altho the term itself seems to be disappearing. It's almost always written as um, and when spoken the unit is generally left off completely.
John

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• posted on August 7, 2016, 2:12 pm
On Sun, 7 Aug 2016 13:44:25 -0000 (UTC), John McCoy

It was always written "um" and is still spoken as "micron". Nothing has changed at all. The unit is *not* left off unless the context makes is perfectly clear. ...no different than any other unit. You don't say "two feet, one inch, and three eighths of an inch", rater "two feet, one and three eighths". No difference.

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• posted on August 7, 2016, 4:46 pm
On 8/7/2016 8:12 AM, snipped-for-privacy@attt.bizz wrote:

In my profession, we used to use "µ" when we published papers in science journals. Now they insist on using "µm". Graham

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• posted on August 7, 2016, 9:33 pm
snipped-for-privacy@attt.bizz wrote in wrote:

My point exactly - there are very few, if any, cases where you'd use um where the context wouldn't be perfectly clear. I can't recall the last time I heard someone say "micron".
John

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• posted on August 7, 2016, 9:58 pm
On Sun, 7 Aug 2016 21:33:13 -0000 (UTC), John McCoy

1. Process technology nodes (e.g. "point one eight micron")
2. Micron memory. ;-)