What is happening with metrication?

I have seen them with tenths of an inch. I believe they are called engineer's tapes.

It does help to have a working knowledge of math.

I do wrought iron. A piece, say 61 inches clear wide has to be divided into equal portions so that all spindles are equidistant. You would divide 61 on a calculator by 12 to give you 5.08333 inches. Now, adding that back to itself, you can scribe the marks, but you have to know the fractional equivalent fairly closely for 5.08333, 10.1666, 15.2499, 20.333, 25.416, etc, out to 61 inches. It's simple but you would be amazed how many can't do it.

And then, if you want to have a casting, the middle spindle must be centered, so you have to divide by an odd number so that one is dead center. Again, simple, but a lot of people can't get it.

I'm for better education.

Steve

NO! Inches are already a fraction of feet. Too complicated. All US tapes should be in decimal feet. Survey tapes already are. In a decimal inch system you would still have the problem of a bunch of measurements adding up to, say, 121.56 inches. Then you still have the problem of converting to feet.

BTW, many "metric" countries use Imperial units for heating and cooling applications e.g. BTU's etc. At least that was the case in most Eastern European countries 20 to 30 years ago. This came about because all of the great textbooks in the early 20th century, e.g. steam tables etc., were written in English. Most plumbing in Hungarian buildings (and elsewhere I suspect) is inch based and identical to ours. Most HVAC stuff is Imperial based.

Ivan Vegvary

NO!! What you saw is tenths of a foot. They are called engineer's tapes. They are further sub-divided into 10 divisions, per tenth, making each division one/hundredth of a foot. Approximate conversion is easy since there are 96 eights in a foot, i.e. almost a hundred. So, approximately, 5 hundredths of a foot is 5/8 of an inch. Close enough for construction but not good enough for machining.

Not really. Like most people involved in US manufacturing for decades, I think in decimal inches. A dimension of 121.56 inches doesn't even make me blink. If I were building ships or surveying land, I'd probably use decimal feet.

The myth of "difficult conversions" is just that -- a myth. Surveyors work in one realm of relative dimensions, machinists work in another. We don't have to convert back and forth.

The point was brought home to me years ago, when Mitutotoyo was my client and some of the sharpest dimensional-measurement people around were my clients. They thought the inch/metric business was 'way overblown, mainly for the reason I cited above.

Where metrics save money or make money, US industry has adopted them. Where they don't, they haven't. Working within a realm of one unit and decimal fractions thereof, such as the inch, thousandth, ten-thousandth, and millionth, as we do in machining, it doesn't matter mcuh what your basic unit is. Leave the non-metric-to-metric problems to the guys who have to convert units of multiple-unit measurements (mmol/mL; foot-pounds times rpm). They use computers to do it, anyway.

-- Ed Huntress

There is no need. The second is a base unit that is not derived from anything. But othere units are derived from it. Why change something that would break everything?

Nick

If this would be the case, the rest of the world would not laugh that much about that "standard" system. But what is really ridiculous is having different units for one physical unit. Length: mils inch feet yard mile furlong chain (OK, just kidding for the last two ones)

Need another example? Volumes: Quite funny that they are different depending on messuring dry and liquid volumes. cup pint quart (fl. / dr.) gallon cubic feet cubic yard cubic inch barrel

(maybe some unused slipped in here)

But that what makes the system so wierd is, that the factors between them are not 10's but (mostly) dozens (or powers of them). With one exception: The mil. But this was an attempt that didn't help that much for a long time. The structures of chips have a resolution of how many mils?

A recent subject: "0.0008661417 inch hole"

Nick

Well thought our comments from you, Ed! (I also happen to agree with all you said).

Ivan Vegvary

Umm, maybe. There are 86,400 seconds per day. Of course, there could be a huge number of other possible factors to choose from, but if you want to make something that works out to nice factors with the earth day, it might get messy.

Jon

The last car I had that was not essentially all-metric was made in 1976. Everything I've had since then has been nearly all metric, except for "convenience" bolt heads like the oil drain, alternator bolts and lug nuts. I've yet to find ANYTHING imperial on our '98 Ram van except the wheel diameter. Probably the cigarette lighter socket is an imperial dimension, as well.

so, that's a 4mm, .79 mm thread pitch?

Jon

Ah, yes, there's a brunette Russian that goes by the stage name "Yulia Nova" and somebody listed her "measurements" in cm units. I had no problem figuring out they were cutting nearly

Jon

But they aren't used in any single context, Nick, any more than you use decameters, meters, decimeters (watch your spelling!), centimeters, and millimeters in the same context. So we don't have to "convert" them in everyday use. An exception would be building construction, but those people often have other problems in getting dimensions right, anyway...

There are others. In metalworking manufacturing we generally use decimal inches, with relatively few exceptions. So we aren't converting from one base unit to another. In fact, in manufacturing, we stick to a single base unit more than metrics users tend to do. And, of course, anyone working at or for a multinational is probably using metrics, anyway. It's a simple system, remember? Any child can be taught metrics in an hour or two.

I won't get into the fact that fractions evolved for a good reason, which is still valid today. Nor will I point out that anything that requires expressing multi-unit values (such as in science and design engineering) is done almost exclusively in metrics in the US -- with no real "conversion problem," because there's nothing to convert.

As I said, and as some native-metrics-using metrology engineers have confirmed for me over the years, the "problem" is a tempest in a teacup. Our use of the inch system (not the "English," or "Imperial," neither of which we use anyway) in business and industry is confined mostly to dimensional measurement, and it causes no problems. In some industries they use selections of other non-metric units, usually within a limited context and with no need to "convert" to or from anything else.

Besides, your base units are pretty foul. Jeez, your thread system is an abortion. And what use are small, whole-number values of micrometers (microns) in manufacturing? The microinch neatly expresses the highest levels of metalcutting precision, as well as being ideal for expressing surface roughness.

Pfffft. So there.

Tell, us, please, where you might use more than two of those in any context where you're NOT dealing with small whole numbers (four cups of milk = one quart of milk, etc.) Do your cooks specify "0.887 liters of milk"? See how silly the "problem" is?

Any how often do you see "mil" used, except in the sheet-goods business? While you're at it, the structures of chips have a resolution of how many millimeters? Or micrometers? Nanometers? Or would you rather have that in decimal decameters?...quick, convert that to centimeters...

We don't use "mils" any more in general metalworking manufacturing. We use thousandths of an inch -- exactly like the relationship between meters and millimeters, only a hell of a lot more useful in the dimensional range in which most metalcutting is actually performed.

How many of THOSE have you drilled, hmmm? Where is the "issue"?

Tempest in a teacup, Nick, one that's used mostly by people who don't think about the practical side of the issue.

BTW, I work in both inch and metrics, 'have for 40 years, and everybody in my old shop was completely comfortable with either system.

Try finding a nut that fits a 5/8" wrench on a Chevrolet.

-- Ed Huntress

On Wed, 30 Nov 2005 00:44:34 -0500 in rec.crafts.metalworking, "Ed Huntress" wrote,

I've got a surveyor's tape marked in decimal feet; would that do?

My mentor told me years and years ago that the French had failed to link the pure decimal system into time because of the way maps (and all world navigation since their creation) are used in navigation and how the exact GMT must be used to get anywhere. It has to do with degrees east and west measured in hours and minutes based on the 60 second, 60 minutes formula. Something to do with the chronometer on every ship at sea.

A little too coarse, like trying to do calligraphy with a bar of soap.

-- Ed Huntress

Hey Ed,

I read in the paper this morning that VW is heating their car body steel to red heat before running it through the presses. What's the story on that?

Randy

Hmm. I haven't read about a red-heat process for bodies. I'll have to look that up.

Pontiac, I hear, is using hydroforming for its new Solstice sports car body. It's too many curves for conventional pressing. And somebody is making aluminum bodies by superplastic forming. That involves heating, but not to red heat.

Do you have a link?

-- Ed Huntress

Then there are Henways....

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

Red or blond?

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

My 94 is a mixture also. Makes things a bit interesting. Having loose wrenches helps with the issues

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner