Measurements - Total Confusion!

[David Collins]

You want a fun mix of metric and imperial? Try working an import milling table graduated in imperial, but made with metric feed screws. Trust me, they're out there.

[Michael Lewis]

Well, we ARE in a transition situation, as our cars and use lots of metric fasteners, and beverage containers are marked in both ml and oz. Several years ago one of my friends was working on his '86 ford diesel pickup, found he needed both metric and inch tools as some parts were manufactured "off shore". I used to have a Norton and my brother had a Matchless motorcycle, we had to have not only Whitworth tools but some British Cycle stuff too. I still have the Whitworth tools and will probably never use them again, but you just never know. It won't totally happen in our lifetimes but eventually the world will use metric for everything.

[Mandolin Mick]

I spend a fair amount of time in Europe and as much as I've tried ... I can't get used to the metric system. Even more annoying is Celsius temperatures! I know how to convert them but if you've spent most of your life with one, you're forever converting it back to the way you learned so that you can relate to the other ...

[PollyCymru]

WOW!

When I wrote that question I had no idea what I'd be starting

Our main problem on this side of the pond is that despite being able to work in fractions of an inch and tenths/hundredths/thousandths of an inch, neither of us had ever seen these expressed as decimals, over here a hundreth of an inch is expressed as a fraction - at least in our world (yep, we're no spring chickens )

Also all OH's tools are imported from Europe, so they are all in metric measurements. And supplies for Luthiers in the UK are measured in mm.

Many thanks to those who have given links to metric/imperial conversion charts they are just the ticket. Don't know why, but OH couldn't find any when he Googled, I don't know what search terms he used.


We have a strange situation in the UK where cars can be either built in metric or imperial measurements, depending on what brand they are and who made them, so garages have to have a set of tools for each or convertable ones

Fruit, Vegetables etc are measured in Lbs/oz or Kilos, but thankfully it doesn't matter as apples and pears etc are the same size regardless LOL


Again, many thanks for your enjoyable and enlightening reponses.

[Rob Grant]

I grew up with the "English" system and converted to metric when I shifted to Oz. I can comfortably use either system, but I prefer metric because I hate those stupid fractions that the English system uses. In some ways I feel like I'm bilingual. What's the big deal about knowing and using more then one measuring system? Like understanding and speaking in more then one language, it stretches the 'ol brain and helps keep it limber.<g>

[Keith Newell]

Your right Ron, I didn't watch what I typed. To go from Metric to inches 10mm divided by 25.4 = .3937 inches
.5 inches times 25.4 = 12.7mm
And as far as working for anything it does. If you are talking measurements in inches or millimeters it has to work. In guitars for instance is the set says it is 9,11,16,26,36,46 then those are in thousands of an inch (.001) so it would be .009,.011,.016,.026,.036,.046 in inches. If a string set showed .04 and it is a smaller looking string then they listed it in millimeters and it is a .016 (technicaly is a .0157") in inches.
Keith

[Ron Hale]

I kinda figured that's what happened, Keith. It's easy to do. As often as I do the conversions, I still have to stop and think when I pick up the calculator!

PollyCymru, fractions are easy to convert to decimal. Just divide the top number by the bottom number. Example: 1/16 = .0625 . ...and, for those hundreds of nit-pickers who are saying "Jeez, he doesn't even know the proper terms", that's divide the numerator by the denominator! So there.

I think it was Bill Gates who said, "The nice thing about Standards, is that there are so many to choose from!" heh heh.

Ronnie

[David Collins]

Our main problem on this side of the pond is that despite being able to work in fractions of an inch and tenths/hundredths/thousandths of an inch, neither of us had ever seen these expressed as decimals, over here a hundreth of an inch is expressed as a fraction - at least in our world

Over here they are written on paper in decimal form, but spoken verbally in fraction form. Machinists in general however, tend not to simplify to tenths or hundredths, but treat the thousandth of an inch more as it's own unit. For example, .04" inches is rarely said to be "four hundredths", but rather spoken as "forty thousandths". A .3" measurement would typically be called "three-hundred thousandths" rather than "three tenths". It actually makes for quite a simplified and accurate means of communicating measurements in my opinion.

Of course I suppose it is a bit quirky that those thousandths are then often divided in to other fractions, such as "half a thousandth" or "quarter of a thousandth" rather than spoken as "twenty-five hundred-thousandths of an inch". Of course it would still be written as .00025", or .000,25", with the understanding that it is generally spoken as "a quarter-thou". Simple, eh? Somehow or another, it all seems to come out making perfect sense to our twisted minds though.

What can make it more confusing is when the terminology is mixed. In many industries (such as the discussing finish thicknesses), they have applied metric terminology to imperial units, therefore one thousandth of an inch is often referred to as "one mil". A finish thickness of "4 mils" is obviously not meant to intend meaning 4 millimeters, but rather 4 milli-inches.

Fun, isn't it?

[woodwiz]

I'm over 60, grew up in the woodworking business using inches. Now I work on violins for a living, and I'm comfortable in both systems. I MUCH prefer metric for working in instruments, including my mandolin, but I'd be OK in decimal inches as well.

What I couldn't work in is halves, fourths, etc. Just too time consuming and hard to read.

.01mm is about .004 inches, and it's a fairly comfortable level of tolerance to work to on graduations and other thicknesses. 1mm is a pretty handy unit of measure for length and width, although tolerances are closer than that. It's easy enough to interpolate two or three tenths when needed.

Apart from that, I agree that it's really difficult to integrate systems:

Metric recipes go by weight, where Americans go by volume measure (weight works better but is more trouble, IME.)

When I worked construction projects in Germany, we did all horizontal measurements in metric to fit with the Graman system, but did all the grading in English so our American equipment operators, would understand. Made for some interesting earthwork calculations, back in the days before PCs or even handheld calculators.

As for construction, you'll always have the problem of legacy systems to deal with. Maybe someone will come up with a modular unit like the 32mm cabinet system that is compatible.

[Tavy]

.01mm is about .004 inches

You mean 0.1mm is .004 inches?

I would be very impressed if you worked to a tolerance of 10 micrometres

Pedantically yours, John.

[Rick Turner]

I've learned to "think" reasonably at luthier's scale sizes in metric, Imperial fractions, or Imperial decimal (US standard machine shop lingo). Where it goes South for me is getting up to cabinet and building dimensions. I just don't easily visualize 1,650 or 4,680 mm very well. Australia is 'twixt and 'tween, too.

For more fun, try remodeling older houses here in the US and especially California. Back in the day, a 2 x 4 was actually 2" x 4". Yes, shim city. We just got used to it. And those old 2 x 4s are hell on your hands...we're talkin' rough rough milled!

[woodwiz]

You mean 0.1mm is .004 inches?

I would be very impressed if you worked to a tolerance of 10 micrometres

Pedantically yours, John.

So would I!

I'd be impressed if I could type, too.

[buddyellis]

Back in the day, a 2 x 4 was actually 2" x 4". Yes, shim city. We just got used to it. And those old 2 x 4s are hell on your hands...we're talkin' rough rough milled!

Hah, we've got a lot of lumber like that in old buildings back home in FL, dimensionally the old wood is 2" x 4". Fun thing is they're made of old growth yellow pine. Toss some of that stuff in an attic for 90 years with the heat cycle of FL summers, and that stuff turns into iron. It laughs at your languid attempts to drive nails into it, and eats your petty screws for brunch.

You have to pre-drill holes into the stuff, and it smells wonderfully like what we call 'fat lighter pine' (turpentine) when you drill into it (lighter pine is basically really old heart pinewood which has a lot of oil in it, and it is used for starting fires). First plate I ever carved was out of the stuff. It's about as tough as carving red maple.

[Darryl Wolfe]

Your right Ron, I didn't watch what I typed. To go from Metric to inches 10mm divided by 25.4 = .3937 inches
.5 inches times 25.4 = 12.7mm

Keith

Hmmmm....Martin Guitars have a 25.4" scale

[David Collins]

Hmmmm....Martin Guitars have a 25.4" scale

The conversion factor of 25.4 often comes up as a convenient theory to explain Martin's seemingly arbitrary number, but it doesn't work out that way when going from imperial to metric - that would only work the other way around (i.e., and 25.4 cm length would convert to an clean 10", but 25.4" comes to 645.16mm). They actually use a 25.34" scale length to determine their fret spacing anyway, which comes to a no more even metric equivalent of 643.636mm. They just call their scale length 25.4, but that's using their own definition of scale length, which is not based on the fret spacing but rather the entire high E string length including an arbitrary and rounded amount of compensation.

A better explanation of their seemingly arbitrary scale length based on my observations, is that it was originally a nice, round, 25_1/2" when they introduced it. Given that they were using the true rule of an even 18 divisor at this time however, the nut to 12th fret, and effective scale length relative to our modern 2^(1/12) spacing ends up at around 25.34". When they converted to the modern spacing system, they simply used 25.34 as the base length on which to space the frets in order to keep the relative string length the same as the old ones. A 25.34" spacing with the modern system ends up the same string length as a 25.516" spacing by the true rule of 18.

Add .060" compensation to conveniently round it to one decimal point, and you get 25.4", which just happens to be the same as the imperial/metric conversion, though this is entirely by coincidence.

[Tom C]

We converted to metric when I was a lad, and now after around 30 years of metric, I hate feet and inches, pounds and ounces etc. We also converted to decimal currency in 1966, whcih was one of the best things we ever did. Now just about every thing is metric, but there are still a few remnants, so you can't really get over it entirely. Building materials and houses are built using metric measurements, and have been for years, so the problems described by Mario are no where near as bad. Renovating old houses can have problems, but nothing that can't be worked around. Cars are built using metric nuts and bolts, and speed is km/hr, fuel consumption is Litres/100km, land areas are in hectares. Problem is most people still think in acres and squares instead of sq m and hectares. Even now, a hectare means little to me even after all the years of metric. You also really do need spanners for both systems. Some things seem to be impossible to convert. We still have bolts and screws in inches and mm, and spanners in inches and mm, and drills, in the hardware stores. Caravans are usually measured in feet, although most manufacturers also provide metric measurements so that is very slowly changing. Most measuring tools are in metric, although you can still get dual system tools. It is not difficult to find high quality metric measuring tools, so I work almost entirely in metric. About the only thing I still talk in inches is for scale length, and occasionally thousands of an inch. Scale length in mm means nothing to most people (including me). So, even after around 30 years of metric, it is still not 100% metric. Weights and volumes seem to have been very successfully converted with just about everthing now measured in ml, Litres, cubic m, and Kg. Personally I think that what was successfully converted is far better off with the metric system. Pounds, ounces, tons and quarts, gallons are just horrible.

Metric money? Can you describe your currency before that?
Here in U.S. we are based dollars.
1 Dollar = 100 cents

[Steve Hinde]

I have worked with German equipment for over 30 years on my day job. Metric is sooooo much easier.
But, with all the German stuff in the factory, all of the threaded pipes are still Imperial. Go figure. The German guys get really confused. The hydraulic pipes are metric, but air and water are not. And then the Japanese metric........who would ever use an 18mm wrench? I have a drawer full of them. Someone needs to tell Sears......
Buy an adjustable wrench....with mm on one side and inch on the other....ever seen those? Strange but true. How about a metric pipe wrench, or screw driver? I have metric screw drivers....Ok, a metric hammer........
Some string packages have the mm listed beside the guage?

Just use 1 or the other....don't convert.

How about 3 Euros for a liter of gas.....you thought gas was expensive...

Steve

[Rob Grant]

"Metric money? Can you describe your currency before that?
Here in U.S. we are based dollars.
1 Dollar = 100 cents"

Peter is referring to pounds, shillings and pence as used in Oz prior to the introduction of metrication (1966). In a sense you Yanks already have decimal currancy.

[delsbrother]

How about a metric pipe wrench, or screw driver? I have metric screw drivers....Ok, a metric hammer........

Isn't everything a metric hammer?

Hey you guys forgot the machinists who'll say "tenths" and mean .0001 ("tenth of a thousandth") ? That always trips up our ESL students in the shop.

[Steve Hinde]

Isn't everything a metric hammer?

Hey you guys forgot the machinists who'll say "tenths" and mean .0001 ("tenth of a thousandth") ? That always trips up our ESL students in the shop.

Only when you try to convert........or it is under the hammer.........