What is happening with metrication?

Seems that someone doesn't know of the CGS, MKS (among others) systems. When one is working in small things - we use centi-meter gram seconds. Big stuff Meter kilo-gram second. The 300' crane would be in feet.dec If metric it would be meter.centi..... Martin Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

Nick Müller wrote:

Oh, goodie. Quick, tell us whether this bolt, diameter 1.854, refers to centimeters or millimeters.

As I said, most of us have been working in metric for 20 or 30 years. And we work in inch. We don't use feet in metalworking, except to refer to rough sizes of stock. We use one unit -- the inch -- and decimal fractions thereof, for almost all work. No deci, no centi. Just inches and decimals. When we write thousandths of an inch (in the metalworking press, anyway) we write 0.00X inches, not "X thousandths of an inch."

When we use metric, most of us don't use deci or centi. It's too confusing.

So there really is no significant difference in that context. Where engineers and scientists deal with complex units, they use metric, and have, for at least 30 years now.

Is that your standard, to have the unnamed unit always refer to the next smaller decimal unit? That's interesting. Most of us probably would say, "two point four meters."

I don't think there's any problem, because they probably aren't working to levels of accuracy that would require decimal anything. But maybe. I'm have to ask a crane fabricator.

Yes, because I habitually work to decimals, probably because of my metalworking experience, and more recently because I spend half my life at a computer or a calculator. The 64th of an inch, as the "standard" precision that was understood unless specific otherwise, disappeared, I'm told, in the

1920s. The standard precision has been 0.005 inch, then it became 0.001 inch, IIRC.

If you start off with a new decimal series for each one, each is a "base," in that you have to divide by ten in your head or on paper to arrive at the next unit.

Here's one thing that we inch/metric users don't like about metrics: Your units are in a decade relationship (10^1). The ones we use in metalworking are in a 10^3 relationship, like most named units in science and engineering: 1 inch, one thousandth of an inch, one millionth of an inch. Fewer ambiguities. There is one oddball, the ten-thousandth of an inch, which we often nickname "tenth" in metalworking. It's convenient for precise work, especially in turning.

Geez. Well, the metric system is a beautiful abstraction. Except for some strange things, like the relationship between joules and calories (0.239006), and between kilogram-force and newtons (9.80665), most of it works out slicker than snot.

I've always gotten a charge out of the inch/metric arguments because everybody keeps talking as if they had no understanding of the strengths and weaknesses of the other system. In the 1960s, the arguments here, put forth mostly by educators, were absurd beyond imagination. Nobody seemed to acknowledge why it's convenient in everyday work to have a unit (say, the foot) that can be neatly divided into whole-number fractions by 2, 3, 4, and

1. Before slide rules and calculators, fractions made a hell of a lot of sense. And our units tended to be such fractions of larger units.

So it's a relic from the past, but fractions are still convenient. Like most people brought up on science and engineering, and (at least) in the presence of slide rules , it's frustrating for me to deal with fractions. But many people still find them to be the sensible units to use in what they do. And you and I, Nick, would be out of luck in doing even elementary algebra without fractions.

The inch system works well with fractions. Many of its units relate to sensible things (the length of a foot or the joint of a finger, for example; the length of an arm or a man's stride), and, today, starting with one of them (such as the inch in metalworking) and then using decimals thereof turns out to be roughly as convenient with one base or another. You just don't want to mix too many bases.

The metric system is a pure abstraction (the derivation of the meter means nothing to almost anyone; the acceleration of kilograms of mass under the force of gravity requires lengthy decimal values to calculate). It's as good as anything else. Ironically, the aspect of measurement we're mostly talking about, which is the measurement of length, is the one in which it matters least whether we start with a meter or an inch.

Where it matters is in those fields in which the newton-meter or the mmols per liter are the units: science, mostly, and engineering. And those are the fields in which the metric system is virtually universal.

I hate the micrometer. It's the most useless unit in metalworking. Many of my Japanese friends agree, BTW.

In the span of 1.6 mm to 36 mm, you have 15 standard sizes in the ISO Unified Coarse system. Within the ISO Unified National Coarse (inch) system, there are 23 standard sizes that fall *inside* of that span. Your screws are always too big or too small. I know, I've cursed at them all.

It's a workaround. Whole numbers are nice.

Well, I find it hard to have a serious conversation about the two systems. They're all silly arguments. Decimal inches work. We don't use the old, odd units, any more than you use odd decades of metrics. We use metrics when they're better. We've built a few things in this country using the inch system, and most of them work. Nobody makes more mistakes within one system or the other. The mistakes come from interactions between the two, sometimes from doing too many conversions.

All in all, a tempest in a teacup.

-- Ed Huntress

Seems that someone isn't up to date with the current state of SI :-)

from

"By 1950 there was some discomfort among users of metric units, because the need to translate between CGS and MKS units went against the metric ideal of a universal measuring system. In other words, a choice needed to be made.

In 1954, the Tenth General Conference on Weights and Measures (CGPM) adopted the meter, kilogram, second, ampere, degree Kelvin, and candela as the basic units for all international weights and measures, and in 1960 the Eleventh General Conference adopted the name International System of Units (SI) for this collection of units. (The "degree Kelvin" became the kelvin in 1967.) In effect, these decisions gave the central core of the MKS system preference over the CGS system. Although some of the CGS units remain in use for a variety of purposes, they are being replaced gradually by the SI units selected from the MKS system."

and

"This rebirth of the metric system as the SI, in effect, did away with the old cgs units such as erg, dyne, and calorie. Later revisions to the SI made it even more explicit that these units should not be used unless absolutely necessary and then only if defined in terms of SI units. Nonetheless, scientists are humans also and habits die hard. Their use is gradually diminishing, though as younger, more modern scientists come onto the scene. Perhaps unit preference could be used as a scientist dating scheme."

and

"International System of Units (S.I. or Système International d'Unités)

Often referred to as the 'Metric System', it is properly named the S.I. system of units. In 1950, there was discomfort amongst users of the cgs and mks (metric) systems and the need to convert between the systems. This was specially true with the derived units used in each of the systems. This necessity to convert went against the ideal of the metric system in general. Thus were the beginnings of the S.I. system. The S.I system of units is a superset of units of which the metric and cgs systems are a member. However, the S.I. system of units has supplanted both the cgs and the metric systems. The SI system of units is largely based on mks definitions for base units, which is probably why it is still referred to as the 'Metric System'. Many of the cgs units are no longer officially recognized as S.I. units."

The only use of centimetres I come across is in clothing size and doctors recording the height of people. Engineering, science and construction use multiples of 1000, so metre, kilometre, millimetre etc.

-- Regards Malcolm Remove sharp objects to get a valid e-mail address

The U.S.A. is moving to the metric system, inch by inch.

-- Mark