Question for designers...

Because "A pint's a pound the world around" makes a better rhyme. ;-)

centimeters,

So does "five foot two, eyes are blue"

Though the song is actually "Five Foot Two, Eyes Of Blue." Almost as titillating as some of the lyrics... "Turned up nose and turned down hose..."

Anyway, when designing the DIMENSIONS of the robot I almost always do it in inches, because once you get used to it they're easy to add and subtract from. I never bother with watts or volts (both of which are metrical) until I'm ready for the escaping smoke part.

-- Gordon

The metric system is for mostly Scientists and Serious Researchers. How ever when things come down to actual construction feet and inches are still recognized as the standard. I know this because when I went to college for computer dafting and computer aided manufacturing we had to learn to draw blueprints in both systems (not too mention work out rules of scale). This lead to alot of problem determining weither drawings were done in metric or imperial measurement. Then getting the equipment to turn out a peice of material with the right realworld dimensions.

The next biggest reason is that America is the world leader in being the "mother of invention". So most patent rights filed at the US Patent Office are set out in imperial not metric.

I'm from Canada. We use the metric system. But when it comes to buying constuction material at any supply store or bulk wharehouse everything is in Imperial. Funny ain't it.

I don't think metric or imperial matters as much as an individual's familiarity with them. If you grow up thinking in one system or or the other the perceived quirkiness of it by others is moot.

Bob

Wasn't there a failure in a mars orbiter due to a NASA subcontractor using Imperial instead of metric units?

Australia changed to metrics a long time ago but you can still by spanners etc in both units and many rulers come with both kinds of units.

-- jc

- Daniel

Whether you work in 746 Watts or 1 Horsepower, the behaviour of your robot is not in the least affected.

The importance is the design and not the units of measurement which can be freely converted to and fro, 2.54mm being exactly an inch.

I have used both. I prefer metric, but usually use inches because here in the USA metric components are much more expensive. It is silly to design in metric if all your screws, shafts, bearings, etc. are in inches. The dials on my lathe and mill are also in inches.

I think a major factor was Napoleon's decision to invade Russia in 1812. That led to a diminishment of French influence.

I've got a feeling that the inch is _defined_ as 25.4 mm. The previous definition was something vague like the length of three barleycorns, or something.

In what way are amp(ere)s not metric?

Deep.

--FWIW I prefer inch, because most of the parts I'll want to tack onto any beastie I build will be listed in catalogs with FPS, rather than CGS dimensions. If you're not in an "imperial" country you'll probably want to stick with metric.

Inches.

It's what I'm used to, and what my rulers are marked in (I've got pretty extensive tool sets in both metric and SAE since I do a lot of car repair as a hobby. But you don't do much measuring when working on cars, so my rulers are all SAE).

While any sane person will recognize that the metric system works better, it's not anywhere as crushingly superior as they told us when I was in school. It's real advantage in europe wasn't that it was better than the old system there, it's that there wasn't a continent-wide system in place: every town would have its own notion of the length of an inch, and there might well be units that were only in use in particular localities. As transportation got better, there was a need for a system of units that was consistent over a wide area. That was the real advantage there.

In the US, there was a nearly continent-wide system in place from the beginning, and there hasn't been a compelling reason to change. As we have more and more international trade, the pressure to change gets stronger and stronger for exactly the same reason as in europe, only on a larger scale.

Of course, tremendous amounts of industry have changed, for exactly that reason. I don't thing there's an SAE fastener on any of the three American cars I've bought that were built in 1995 and later. By contrast, I don't think there's a single metric fastener on my 1978 Newport.

Just by the way, you do realize that amps are a metric unit, don't you?

---- Right. As I recall it was one of the first conversions from the standard HP, Watt and Volt.

The US really needs to make more of an effort to convert. It's something that won't happen unless it's forced on people because we all will just continue to think in terms of the system we already know unless forced to learn the new system. If we are not forced to deal with metric systems we will never learn to see things in terms of their metric dimensions. Everything we buy in the US is measured in Imperial units so that's what everyone still thinks in the for the most part. Food is often marked in both, but it's kinda stupid to see something labeled 1G/3.78L and expect us to to learn to think in liters.

The U.S. already has a well established, and powerful metric system.

It's called the Dollar!

Don...

In Australia we converted to the metric system a long time ago but it takes a generational change, not force. The olds will struggle converting pints to liters, yards to meters but the young will simply use liters and meters.

I would not like to be forced to change from the QWERTY board layout to a more efficient layout but see no reason, with a programmable keyboards, you could not accommodate both.

-- jc

It's getting there indeed. The stock exchanges have switched from fractional share value (as in 2 7/128) to decimal dollar amounts a few years back.

Metric is not necessary in everyday's life, and the US is hugely invested in the imperial system. However, in time, I trust metric will be adopted, just like stock exchanges have broken with a century long tradition of using fractions.

Serge

It only worked because for each part of the changeover, there were statutory dates by which all items, e.g. for sale, must be first identified in dual units, and then by which the pricing must be in metric only. When metric is all that's available at, e.g., the green-grocer's, everyone has to learn the new system.

Jimmy Carter tried to introduce metric by "accommodating both", and it was a near-total failure.

Yeah, I'm sure the same thing would happen in the US. It would only be the younger generation that would adopt it. But until it's forced, the younger generations keep getting addicted to the Imperial system and become one more generation that will never change. Even though they are all now taught the metric system in school at the same time they learn the Imperial system, because they don't use it in their day to day lives they never really learn to think in metric terms. Gasoline, milk, and water is sold by the gallon, everything is sized in inches, temperature is reported in fahrenheit, distance is in miles and speed limits are in MPH. Until all these day to day things are forced to be converted to metric, the younger generations will keep growing up to be one more generation that will refuse to convert.

Even though the advantage of metric is small, and the conversion cost very large, there's an on going cost associated with supporting the dual system that is time and money wasted every year you put off he conversation. Mechanics have to have two complete sets of tools, children are taught two systems in school, manufactures that try to support multiple markets have to produce produces that are compatible with multiple standards (from rulers to printers, to paper sizes to mechanical standards etc).

I think it's inevitable that the metric system will be the world standard (and it already is in many fields like science and medicine) and all of us still in the dark ages will have to convert at some point, so the longer we put off the conversion, the more time and money we are wasting supporting the dual systems, and the more we continue to isolate ourselves from the rest of the world.