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why is the US not Metric

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Tepe:

--- Quote from: forrestc on February 19, 2020, 02:09:09 am ---Take building lumber.  Today in the US, the most commonly used building stud size is 38x89 mm.   Are you advocating just labeling it 38x89 instead of "2x4" which really means "1.5inx3.5in" (don't get me started)?   Or changing to some metricated "rounded" dimension like 40x90 and 40x140?

--- End quote ---
Would 40x90 be within the present acceptable tolerances? If so, then call it 40x90 (or 90x40).

In these parts we actually have dimensions like 57x38, 75x47, 47x100 and other funny values.
At least 2x4 sounds a lot better :-)

xrunner:

--- Quote from: ebastler on February 19, 2020, 06:24:09 am ---What emoticon would it have taken to make you understand the sarcasm in Mr. Scram's comment #1310?

--- End quote ---

Now you're just being sarcastic.

KL27x:

--- Quote ---(from forrestc: If you look at the building specs in our "metricated" neighbor to the north, you'll find that the stud sizes and things like minimum spans are listed in metric dimensions which are oddly not even.  Such as the maximum stud spacing is listed as 406mm which just happens to be 16inches converted to metric and rounded to the nearest mm.

--- End quote ---
...And if you go up there and watch a house being built in Canada, you will see that everyone in the construction industry uses an imperial tape measure. Because that just happens to make it easier. If they used metric tape measure, these numbers will be retarded. Most these guys continue to use imperial when they build things at home, even knowing how quirky, obtuse, backwards, and other adjectives that BSFEE knows, because despite all that, it works just as well for this.   

This situation is created by history. But there are also industries where the numbers in imperial work out better just because of the real world. E.g. machining and manufacturing. It just so happens that our ability to make things that don't require mega time and money from skilled human hands and eyes and the resolution which actually matters comes down to a thousandth of an inch or three, in many cases. Another example is firearms. Bullets will come in different sizes for barrel variation. And they will make and sell them in 1 thous increments of diameter. That is just a good step size for this. So sometimes it's random chance what makes one more useful in some context than the other.


--- Quote ---Would 40x90 be within the present acceptable tolerances? If so, then call it 40x90 (or 90x40).

--- End quote ---
This "wrong naming" of the 2x4" we have is more an anomaly than anything else. So take this exmaple and apply it to air filters, door sizes, window frames, everything we make and buy that is listed by dimensions. Are you going to just rename everything by rounding up down to nearest 5 or 10 or more mm? (And will the industries also round DOWN when it goes over by some amount? Or will they always round up, for marketing/psychological reasons or whatnot... like everything costs 19.99?). And so we live in a world where dimensions don't mean anything until you look up the datasheet?

And besides. We know that to get the true nominal dimension of this lumber, we subtract exact half an inch. So a 2x4 is nominally 1.5 x 3.5". A 4x4" is 3.5x3.5" A 2x8" is 1.5 x 7.5". If we do this mm rounding... well, then you would have to either look up the actual "datasheet," or have a great memory, or convert it into imperial to see what that comes out to in imperial and round to the nearest half and inch. Then convert back to metric?

I posit it is easier to just leave it in imperial, even if you use metric tape measure in your shop.

forrestc:

--- Quote from: KL27x on February 19, 2020, 06:58:10 pm ---...And if you go up there and watch a house being built in Canada, you will see that everyone in the construction industry uses an imperial tape measure. Because that just happens to make it easier. If they used metric tape measure, these numbers will be retarded. Most these guys continue to use imperial when they build things at home, even knowing how quirky, obtuse, backwards, and other adjectives that BSFEE knows, because despite all that, it works just as well for this.   

--- End quote ---

I was in hopes that I'd get some clarity from the metric advocates on the list about exactly what they're advocating, because doing things like they've done in Canada with the building code is somewhat silly.   If all you're going to do is to go through the official documents and anywhere you see "inch", convert it to mm in the spec, then what you've done is introduce additional complications.   Now you have to deal with 404mm on centers, and odd specs for dimensions of 2x4's and so on.   So you've got a mm tape measure, and somehow have to put something on 404mm centers?   For things like this, it is definitely easier to just leave it alone.   Which is what has happened in the US and Canada, with the caveat that the Canadians have oddly converted their building codes in at least some of the provinces to metric.   So the building codes spec 404mm on centers, and everyone knows that's 16" and they continue to use their inch tape measures.

If you were really going to metricate the building industry, you'd want to switch to something like 50x100 studs, and hopefully a larger 50x100 stud would permit you to use 500 mm centers.  Your board lengths would move to meters, etc.    I don't know if any of the numbers I just spouted make any sense, but laying out studs on 500mm centers is a lot easier than laying them out at 404mm (I'm ignoring that 404 is close enough that you could just use 400mm to make my point).  BUT - doing that now causes the whole nightmare of how do you deal with the fact that newer houses are all on the new stud size, and the older ones are on the older spec.   So that isn't a good option either.

tooki:

--- Quote from: forrestc on February 20, 2020, 05:57:48 am ---
--- Quote from: KL27x on February 19, 2020, 06:58:10 pm ---...And if you go up there and watch a house being built in Canada, you will see that everyone in the construction industry uses an imperial tape measure. Because that just happens to make it easier. If they used metric tape measure, these numbers will be retarded. Most these guys continue to use imperial when they build things at home, even knowing how quirky, obtuse, backwards, and other adjectives that BSFEE knows, because despite all that, it works just as well for this.   

--- End quote ---

I was in hopes that I'd get some clarity from the metric advocates on the list about exactly what they're advocating, because doing things like they've done in Canada with the building code is somewhat silly.   If all you're going to do is to go through the official documents and anywhere you see "inch", convert it to mm in the spec, then what you've done is introduce additional complications.   Now you have to deal with 404mm on centers, and odd specs for dimensions of 2x4's and so on.   So you've got a mm tape measure, and somehow have to put something on 404mm centers?   For things like this, it is definitely easier to just leave it alone.   Which is what has happened in the US and Canada, with the caveat that the Canadians have oddly converted their building codes in at least some of the provinces to metric.   So the building codes spec 404mm on centers, and everyone knows that's 16" and they continue to use their inch tape measures.

If you were really going to metricate the building industry, you'd want to switch to something like 50x100 studs, and hopefully a larger 50x100 stud would permit you to use 500 mm centers.  Your board lengths would move to meters, etc.    I don't know if any of the numbers I just spouted make any sense, but laying out studs on 500mm centers is a lot easier than laying them out at 404mm (I'm ignoring that 404 is close enough that you could just use 400mm to make my point).  BUT - doing that now causes the whole nightmare of how do you deal with the fact that newer houses are all on the new stud size, and the older ones are on the older spec.   So that isn't a good option either.

--- End quote ---
I also broached the question of relabeling vs. physically re-sizing things somewhere earlier in this thread, but of course they never responded...

Anyway, as an American living in Switzerland, I can weigh in with some observations on this, because Switzerland has done some of each.

On the one hand, many things in Europe are simply "old sizes written in metric", and while it's been long enough that most folks don't remember the old units, nonetheless this is common. Examples include screwdriver bits ("6.3mm", which is 1/4"), electronics components ("2.54mm pitch", aka 0.1"), and countless other items whose sizes were standardized ages ago, be it on UK, US, or pre-metric European standards.

On the other hand, Switzerland often had its own standards, at odds with European standards. A great example of this is the standard widths for built-in kitchens, and the appliances that go in them. The European standard is 60cm, the old Swiss standard is 55cm. Until around 20 years ago, kitchens here were built to the old standard, meaning you (as an individual or a manufacturer) couldn't import cheaper 60cm appliances, because they physically could not fit. This left you at the mercy of the 55cm appliances made specifically for the Swiss market, necessarily at a higher cost. Newer kitchens are all built to the 60cm standard, and most appliances sold here are, too, though the Swiss manufacturers (or Swiss subsidiaries of foreign ones) still make a handful of 55cm appliances for retrofitting (at least those they can also sell with a trim kit for 60cm kitchens).


Also, no longer talking about Switzerland, some other situations:

A third category would be things that are commonly written in customary units but whose controlling dimension is actually metric, like the 3.5" floppy disk (whose dimensions are actually 9cm), and TVs and computer displays.

The final category is things commonly written in customary units in USA, in metric elsewhere, but whose actual controlling dimension was neither metric nor customary, where the marketing dimensions are really more of a named size than an actual reflection of the physical dimensions. I guess many old tooling sizes were like this. I can't think of any examples off the top of my head, but I've seen things like this.

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