mm verses inches

Hi, I'm writing a book for the American market, and my understanding is that you guys don't really use the metric system.

In the UK, we kind of use both in everyday life, in a mad sort of mixture. We buy petrol (gas) in Litres, but we buy drain pipes and wood mostly by the foot and cloth by the yard.

Anything technical is likely to be in metric units. So drill bits etc are in mm.

I have a question for you Americans. To what extent do you use mm. Do I have to convert every measurement into mm and ounces, or are you happy seeing things in a book in mm and grams?

To me, (being American) I prefer the American system becasue it's what I've known all my life, but every ruler has a cm side to. And things like drill bits come in both fractions of an inch, and millemeters.

Well to me it would depend on the subject and market you are aiming at. If it is a technical subject then I don't think metric units are a problem at all for the U.S. market. Now those Canadians, who can tell what the heck they measure with, eh. :wink:

Lefty

to me I prefer the metric system, its a royal pain in the ass to remember 10 an 18/32

but I know I am a minority

I agree that a technical book should have no problems using metric measurements. (Cookbooks, or woodworking, on the other hand...)
In the hobbyist market ("Arduino Projects for Evil Geniuses"?). use of metric may even lend a sense of "realness" to things (science classes tend to be taught using metric measurements, for example...)

The Good Ol' Boy in me says American Standard. I grew up in metal shops and EVERYTHING was American Standard... drill bits were fractions and numbers. I really can't remember the last I was ever forced to work with the metric system; maybe assembling kit furniture or a barbecue that came from China?

If this is aimed at American first timers, then you might want to choose one system and stick with it instead of bouncing back and forth between two different measurement systems, and I think most Americans would think it's odd to see a book written in metric.

All that said, I have zero idea what they're teaching kids these days in school. They've been talking about switching to metric ever since I was a kid... maybe they've started? (although I don't think they ever will)

Thanks everyone, thats actually a real help.

Sounds like the US is more like the UK than I thought with using both systems.

Its too late for the 30 Arduino Projects for the Evil Genius. In that I mostly did inches with mm in brackets after it.

But for the sequel (the book I was referring to), I don't think I'll worry as much about it. I think perhaps mm for drill bits, LEDs, anything kind of scientific or requiring a degree of accuracy and inches with cm in backets for dimensions of wood and box sizes etc.

It kind of sounds like most of you would be more or less ok with that.

Actually, drill bits would be one of the things that would be better to do in English units, since metric bits are hard to find and usually overpriced. (Exceptions for tiny carbide PCB bits, that are hard to find and overpriced in either units.) Science is doable in metric, but commerce is still pretty much 100% English.) (Interesting exception: recreational beverages. 2l and 1l soda bottles, 1l or 750ml booze.)

All that said, I have zero idea what they're teaching kids these days in school.

You might be shocked.

It might be something peculiar to Arizona, but my friend was having problems helping her child with his math homework; he was in 5th or 6th grade at the time. She asked me to look at it.

It was one of the more stranger things I've ever seen; it looked like math equations, except there were no numbers involved - just shapes (like circles and triangles), as well as various mathematical symbols (+, -, =, x, etc).

Looking at the example problem on the homework sheet was confusing as well. All in all, I had seen simpler problems on IQ tests; in fact, the problems reminded me of such IQ test problems.

With a little thinking, I realized that what the math problems were teaching was a form of simplified algebra - except instead of using standard algebraic symbols (ie, numerals and letter variables like x, y, and z) - symbols were used instead (symbolic algebra?). Once I hit upon that, it all was fairly elementary.

What shocked me, though, was that they were teaching this to elementary school children; this wouldn't be so bad, but I tend to wonder how it would effect the learning of standard algebra and later "higher" maths in junior high and high school levels. I don't so much have a problem with teaching elementary school children algebra, but if you're going to do it, perhaps teaching them the standard methods, then advancing into symbolic methods, might be the better way...?

Then again, I'm not an educator - maybe there's something in teaching using a symbolic method, then switching to the more standard method in later years, that works better in teaching algebra?

I also tend to wonder how other parents cope with it - those who may have never seen anything like it before in their life, and don't have experience thinking "outside the box", or have friends who tend to do that on problem solving; how do they assist their kids?

Maybe Arizona tends to be a "testbed" for new math teaching methods?

not to derail the thread but there was a recent story on slashdot

apparently they have been screwing it up so bad students are failing to grasp the actual meaning of the = sign

and () no longer means do this first, it apparently means X

of course I have seen what it takes to be a teacher in the US, and the future does not look bright (one of my friends is a teacher, after most of a 4 year degree, which was with only about 60% being there, and the most of that time they were under the influence)

if he can fudge being a teacher for 5 years he gets a 5 year contract, which rolls him into a 10 year contract

I'll chime in. While we in the USA are trained from childhood to embrace imperial inches... there remains such beauty in the decimal system for me that I never "avoid" it. Since my high school physics days I have no issue understanding what 10mm is or how much water is 100ml. So while I don't use it everyday, the metric system is not beyond my ability to cope.

So for me personally, I have no problems with things being expressed in the somewhat more universal metric nomenclature. It's certainly "nicer" to my eyes to read 3.175mm versus the mind-bending 1/8th specification.

I have no problems with things being expressed in the somewhat more universal metric nomenclature.

Now how in the heck would you or anyone else around here know if the rest of the universe uses the metric system. Hell the universe may still be dealing in Cubits. People on Earth can be so arrogant.

Lefty

you could always just piss everyone off and use decimal inches. ;D

Standard engineering units are now metric. If you did an engineering drawing for someone who is not in the US and you did it in inches, they would slap you silly.

For rough measurements I use inches and occasionally feet. Obviously we all still use mph rather than kph though.

I can see why people use inches instead of mm if that's how they were taught and that's what they have always done but I don't think there should be anything new produced in inches, it's just a pain in the ass.

I do think that most students are taught that there are 2.54cm in an inch (yes they should be teaching that there are 25.4mm but hey), but I don't think many students could tell you that if you asked them.
They might know it was 2 and a bit...

Mowcius

Standard engineering units are now metric

Indeed - the inch is defined as 25.4mm. ;D

I'll chime in pretty much what everyone else is saying.

To me, .1" is nice than 2.54mm. That said, some things are nicer said in mm (such as 3 mm or 5 mm LEDs). I don't think you'll have to worry too much about which units you use. If it doesn't say what the measure is in inches, I'll just type it into Google ;D.

what is .1 inch, imperial doesn't use decimal guess you mean 1/64th, course being in the age where every single thing is displayed on a digital screen what are you going to do

it really is complicated, meanwhile metric continues to be 2.54mm, maybe that is why most of the world accepts it for daily use, and science demands it

Ah well, I tried :P.

what is .1 inch, imperial doesn't use decimal

it is decimal inches, in other words, 1/10 of an inch, or 100mil/thou.

heh see its mind boggling

0.1 = 1/10 of an inch which is 1/64th of an inch

who the * thought this crap up

(and yea its still 2.54mm)