Metric and English Conversion

[Mark Grotenhuis]

While mounting some euro-hinges and euro-drawer glides. I found myself wanting to give up converting everything and just use metric. This got me thinking ... How do Europeans buy wood? In America we use the board foot unit which is 12"X12"X1" What do Europeans use? Cubic meters? Board Centimeters? Anyone know? I cant wait to tell my local sawmill guy I want my wood in metric and watch the gears in his head grind to a stop.

[Walter Plummer]

I posed that very question to Fine Woodworking over a year ago and got a reply from an editor saying they wanted to use it in the magazine. Unless I missed the answer somehow, they never did.

[Eric Wheeler]

Shoulda asked this a couple years ago. I am no longer on speaking terms, but had a friend who married a girl from Germany, and her father was very much into woodworking.

[ian maybury]

Sorry I can't help either. I was trained at different stages in both the metric and imperial systems, and have used both for quite long periods.

In Ireland the UK wood coming from a timber merchant is usually still sold in cubic feet or by the cube - not board feet. On the other hand most machined stock comes in mm.

I've no idea what the practice in Europe is.....

ian

[Gary Curtis]

:(When I was starting out working with wood I got one machine that provided a lengthy manual with tutorials and lessons — all in Metric. They talked about boards in so many CM, Centimeters. The strange thing is, with long boards, the measurements got into the thousands of CM, instead of so many Meters + a few CM. Seemed pretty inconvenient to be talking about 1400cm (about 4 feet)

I was new and had to decide if it was to my advantage to learn Imperial or Metric. So I wimped out and went for feet-inches-fractions and all the complications that entails. I got a $14 carpenter's calculator to crunch the numbers when my head starts to spin.

Where I really envy Canadian, Brits and Germans and others is in their ease at calculating volumes and in the 36mm cabinetry system.

[Rick Fisher]

Ya know.. Canadians are metric too .. lol.

I am in the building supply business in Canada.. We sell in both metric and Imperial. Plywood is actually bought in metric.. but we sell it in imperial.. So we buy 9.5 mm x 1220 x 2440 Standard sheathing.. and sell 3/8" x 4x8.

In Europe, plywood is simply 1220 x 2440 and lumber is sold by the meter...

In Canada, logs are sold by the cu Meter.. mills will buy in Cu meter but sell in BF ..


The reason they would say 1400 cm is that its simple. The Imperial system is complicated, so its natural to expect that metric will be even more complicated, because your not familiar with it.. but the truth is that its much simpler.

1400 cm is actually 14 meters, just under 50 feet. 1400 mm is 140 cm or 1.4 meters..

You would not say 1400 inches long, because you would have to divide by 12 to get feet.. but in Metric.. 1400cm is simply 14 meters.. Rather than write 14M + 3 cm .. which is how you would write 14' 3" .. in imperial.. you can just say 1403 cm ..

In other words.. Learning metric is easy.. converting it to imperial is difficult.. Since most North Americans still think in Inches and feet.. its complicated.. If you just built in Metric.. you would find it simple.

[Brian Jarnell]

Builders here in NZ talk in mm, other trades in cm.

4x2 is 100 x 50.

I am getting on a bit and still think in imperial, but work in metric.

[Rod Sheridan]

I finally gave up on the Imperial system when I decided to make some kitchen cabinets using the 32mm system. Converting from metric to imperial simply added complexity and increased the errors.

So when I bought a new planer I order the digital height gauge in mm. I also began making all my drawings and furntiure in metric units.

Boy, is it ever easier, no odd fractions to add or subtract so far fewer calculation errors.

For simplicity, use 20mm thick material instead of 3/4", etc.

Regards, Rod.

[Chuck Wintle]

I finally gave up on the Imperial system when I decided to make some kitchen cabinets using the 32mm system. Converting from metric to imperial simply added complexity and increased the errors.

So when I bought a new planer I order the digital height gauge in mm. I also began making all my drawings and furntiure in metric units.

Boy, is it ever easier, no odd fractions to add or subtract so far fewer calculation errors.

For simplicity, use 20mm thick material instead of 3/4", etc.

Regards, Rod.

I have to agree with Rod in that its much easier to use either metric or standard and not try to convert back and forth. Once one gets used to the idea of 50mm x 100mm (2 x 4) then its easy. and since the metric system is base 10 it alos jives with the regular number of fingers on human hands.

[George Neill]

The US Metric Association web site (http://lamar.colostate.edu/%7Ehillger/) might be of interest to those wishing to make their lives simpler.

[Rick Fisher]

If you force yourself to learn the metric system.. (and enter the 20th century. :) ). Learning to adapt imperial to metric will happen automatically.. I am sure Rod agrees, it just starts to happen.

[Brian Jarnell]

Allways some reticence to change..

Certainly easier when you get used to it.

[Jaromir Svoboda]

What do Europeans use? Cubic meters? Board Centimeters? Anyone know? I cant wait to tell my local sawmill guy I want my wood in metric and watch the gears in his head grind to a stop.[/QUOTE]

Cubic meters.

[Mark Grotenhuis]

I finally gave up on the Imperial system when I decided to make some kitchen cabinets using the 32mm system. Converting from metric to imperial simply added complexity and increased the errors.

I'm interested in learning this 32mm system. Can you guide me in the right direction? A book or PDF or webpage maybe? Do you know any good places to buy metric measurement tools?

[Rick Fisher]

Mark, up in Canada pretty much all tools are Metric and Imperial. So a Stanley tape will have Metric on side of the blade, and Imperial on the other.

You can also buy tapes / Rulers which have only metric or only imperial, but the norm is to have both. .

If you like higher end stuff.. Lee Valley should sell Metric measuring tools.. otherwise, any Canadian tool store/ Outlet.

[Darius Ferlas]

How do Europeans buy wood? In America we use the board foot unit which is 12"X12"X1" What do Europeans use? Cubic meters? Board Centimeters? Anyone know?

Lumber is always bough by cubic meter.

Furniture and architectural design elements are usually in millimeters, but in retail the dimensions will be often in centimeters. In practice it doesn't really matter. All you need to do is either add zeros or shift the decimal point. The table below might seem a little scary but in every day life you'll fit in between 0.001 and 1000 most of the time (mili- and kilo-)

http://www.radioing.com/eengineer/metric.gif

[Harlan Barnhart]

I may be alone on this but I think the Imperial system has advantages for working with middle sized numbers. For very large (for example measuring space) or very small (measuring a molecule), base ten units make computing easy since we use a base ten numbers system. BUT for some things a base 16 system is really nice. For example, I often need to find the center points of various measurements. When a fraction is involved it is often easier to divide a base 16 number than a base 10. Half of one is 1/2, half of 1/2 is 1/4 half of 1/4 is 1/8 half of 1/8 is 1/16. With a base ten system you quickly run into undesirably lone numbers, .5, .025, .0125, .0625. Maybe the best would be to adopt a base 16 numbers system first. Then the "decimal" would align with the "fractional".

[David Cefai]

I cannot speak for all of Europe but in Malta we buy wood by the cubic foot, plywood by miilimetre thickness, manufactured and laminated board by Imperial thickness and in 8x4 sheets.

Then we take it home and work mostly with metric size tools and fasteners.

I believe that the UK buys its timber in Imperial sizes too.

Italy has been metric since the year dot. But they still use inches and feet sometimes! I don't know how they buy their wood though and currently don't have a handy friendly Italian to ask.

[Rick Moyer]

I may be alone on this but I think the Imperial system has advantages for working with middle sized numbers. For very large (for example measuring space) or very small (measuring a molecule), base ten units make computing easy since we use a base ten numbers system. BUT for some things a base 16 system is really nice. For example, I often need to find the center points of various measurements. When a fraction is involved it is often easier to divide a base 16 number than a base 10. Half of one is 1/2, half of 1/2 is 1/4 half of 1/4 is 1/8 half of 1/8 is 1/16. With a base ten system you quickly run into undesirably lone numbers, .5, .025, .0125, .0625. Maybe the best would be to adopt a base 16 numbers system first. Then the "decimal" would align with the "fractional".

I have not used metric to this point, but I suspect if you were building using the metric system you wouldn't build to "fractions", you would build base ten dimensions. Yes 1/2 of 37cm is 18.5cm or 185mm, but that's still easier than adding or subtracting 16ths and 32nds! Make something with that in mind like you would now.
ex: I want a pc. 3' tall so I can have my shelves about 1' equally spaced. In metric maybe make something 90cm tall with each shelf 30cm. I'm sure our Canadian/European/Aussie.....friends can give better examples.
I feel blessed to have been born in this country, but I find it almost embarassing that we still use such an antiquated system of weights and measures.

[Rod Sheridan]

Hi mark, there are many books available on the subject, I suggest you look at woodworking stores.

http://davelers.com/32mm/Basics/157.html

The above link provides an introduction to the 32mm system.

Basically the system works in increments of 32mm with holes drilled in rows inside cabinets. The distance from the front and back, as well as the bottom are standardised, and all hardware types from hinges to slides fit these holes.

You don't have to drill every hole, I normally only drill one above/below each planned shelf location to allow minor adjustments unless I haven't a clue as to what's going to be stored on the shelves. I like that look much better than an entire row of holes.

The trick is to use metric measurements and design values. The 32mm system is extremely well engineered and once you understand it, you'll find it very fast, efficient and flexible.

You can buy metric measuring tools at any good supplier.

Regards, Rod.

P.S. An internet search will yield more info, however a good book will be a great help.

[Dan Schocke]

Just how "new" do you folks think the metric system is? I may be a little off, but as I recall it was first defined and used in the 18th century. It wasn't widely adopted until the 1960s, but it certainly isn't a recent invention. There's nothing antiquated about the imperial system -- it's just a different system that uses a different set of standards. The standards for both systems are somewhat arbitrary and only apply to everyday life once your brain learns to associate them with something. If you really think the metric system makes sense, ask your favorite european how many Newtons he/she weighs...

[Jamie Buxton]

What do Europeans use? Cubic meters? Board Centimeters? Anyone know? I cant wait to tell my local sawmill guy I want my wood in metric and watch the gears in his head grind to a stop.

Cubic meters.[/QUOTE]

Really? Cubic meters seems like such a big unit. For instance, yesterday I bought a board that's 7" by 8' by 1" thick. That's five board feet. If I'm doing my conversion correctly, it would also be .0083 cubic meters. Liters would be a unit more like the usual size of boards. That board would be 8.3 liters. Of course, we'd all be confused when we buy lumber and Coke with the same unit.;)

[Rod Sheridan]

Cubic meters.

Really? Cubic meters seems like such a big unit. For instance, yesterday I bought a board that's 7" by 8' by 1" thick. That's five board feet. If I'm doing my conversion correctly, it would also be .0083 cubic feet. Liters would be a unit more like the usual size of boards. That board would be 8.3 liters. Of course, we'd all be confused when we buy lumber and Coke with the same unit.;)[/QUOTE]

Jamie, I get 0.39 cubic foot (7" X 96" X 1" /1,728).

I agree, one cubic metre would be a large unit for wood purchases........regards, Rod.

[Rod Sheridan]

. If you really think the metric system makes sense, ask your favorite european how many Newtons he/she weighs...

Well Dan, since the Newton isn't a unit of mass he/she may not know.

However if they know their mass in Kg, they could multiply it by 9.8 m/s to obtain the force they exert on the floor.:D

It would be similar to asking someone in North America what their weight is in poundals.

regards, Rod.

[Darius Ferlas]

Really? Cubic meters seems like such a big unit. For instance, yesterday I bought a board that's 7" by 8' by 1" thick. That's five board feet. If I'm doing my conversion correctly, it would also be .0083 cubic feet. Liters would be a unit more like the usual size of boards. That board would be 8.3 liters. Of course, we'd all be confused when we buy lumber and Coke with the same unit.;)

Jamie, and how many board feet do you buy when you buy firewood? Or do you buy them by the cord in the US?
Similarly, when you're buying a single board of the dimensions you stated you'd buy it as a board with the dimensions you stated. The price would likely be calculated in cubic meters because that's how wood is traded, however small the number would be. To you it would still be a board 8 feet long, or 1000 8 feet long boards.

Liters is used for volume (mostly fluid) but is actually not a part of the official SI system. Instead cubic decimeter is used and it is equivalent to 1 liter (1/1000 of a cubic meter). If the unit level is too small or too big you can use one higher or smaller. Similarly, you know that a distance from Berlin to Paris is not expressed in light years or millimeters.

When you buy wood in quantities other than a size of a match then you will definitely buy it by cubic meters. That's how cabinet makers and builders buy. So 100bf a hobbyist would buy is roughly 0.25 cu meters. I think it's quite a manageable number. Also, using the number such as .0083 cubic meters is an attempt to transplant the SAE standard to metric realities, and if correct, the number no more ridiculous than 4.67 b/f ;)

[Jamie Buxton]

...
Liters is used for volume (mostly fluid) but is actually not a part of the official SI system. Instead cubic decimeter is used and it is equivalent to 1 liter (1/1000 of a cubic meter)....


I think you're making my point for me. While cubic decimeter may be an official SI unit, people use liter. They use it because it is a convenient size. Cubic meters is a convenient unit if you're buying some things -- for instance concrete -- but not so convenient if you're buying others -- for instance Coke. Cubic decimeters, while an ideologically pure unit, is too much bother to write out. So folks use liters, whether or not it is official.

[Dan Schocke]

Rod, you hit my point exactly... Kilograms are units of mass, not weight. Weight is mass multiplied by local acceleration due to gravity, and the unit for that in the metric system is Newtons. Pounds, on the other hand, are units of weight, not mass. As human beings cannot sense mass, the kg is somewhat useless as a unit of measure in everyday life.

The poundal is a unit that was really invented to make force calculations simpler in the English system of units, so not sure how that applies here.

[Rod Sheridan]

Rod, you hit my point exactly... Kilograms are units of mass, not weight. Weight is mass multiplied by local acceleration due to gravity, and the unit for that in the metric system is Newtons. Pounds, on the other hand, are units of weight, not mass. As human beings cannot sense mass, the kg is somewhat useless as a unit of measure in everyday life.

The poundal is a unit that was really invented to make force calculations simpler in the English system of units, so not sure how that applies here.

Dan, you're correct, it's been so long since I've used the BE system I forgot that. However I don't think I've ever seen Kg used for anything other than mass.

As for not being able to sense mass, I'm not sure I would agree with that, we only sense force however we can sense mass in both instances where there is gravity and no gravity. If there's no gravity, theres no weight, however we can sense mass by pushing on the object with our finger.

Mass tells us how much matter is in the object, so does weight if we know what the gravitational acceleration is. (fortunately for me I only work on earth so I don't have to worry about that :D).

I think in both systems that the average person doesn't understand the units, any quick quiz will demonstrate that, however the metric system is a lot eaier to use.


regards, Rod.

P.S. I was surprised to find that the difference between the Imperial system and the American system was due to updates happening in the Imperial system after the Revolutionary War. I had always assumed that the US had modified their system after the break from England.

[Josiah Bartlett]

I have not used metric to this point, but I suspect if you were building using the metric system you wouldn't build to "fractions", you would build base ten dimensions. Yes 1/2 of 37cm is 18.5cm or 185mm, but that's still easier than adding or subtracting 16ths and 32nds! Make something with that in mind like you would now.
ex: I want a pc. 3' tall so I can have my shelves about 1' equally spaced. In metric maybe make something 90cm tall with each shelf 30cm. I'm sure our Canadian/European/Aussie.....friends can give better examples.
I feel blessed to have been born in this country, but I find it almost embarassing that we still use such an antiquated system of weights and measures.

Its really easier to just work in tenths or 100ths of a mm, just like machinists do. (Machinists work in 100ths of inches as well as SI units).

I'm an electronics engineer, we work in mils and um (micro meters). Circuit boards are in mils, IC's in um, generally. It can cause confusion, but at least it avoids fractions.

[Glenn Vaughn]

Lets further complicate the question.

If I buy a 2 X 4 I get a piece thaty is nominally 1 1/2" X 3 1/2".
If the metric equivalenty is 100mm X 50mm (1.968" x 3.937") would I get 100mm X 50mm or would I get a nominal size that is equivalent to the 1 1/2" X 3 1/2" American?

[George Neill]

Inching Forewards (http://pegsandtails.wordpress.com/2010/01/12/inch-by-inch/) casts some light on the history of both systems of measurement. Also, check out the links in Pat Naughtin's comment at the foot of the page.

[Darius Ferlas]

I think you're making my point for me. While cubic decimeter may be an official SI unit, people use liter. They use it because it is a convenient size. Cubic meters is a convenient unit if you're buying some things -- for instance concrete -- but not so convenient if you're buying others -- for instance Coke. Cubic decimeters, while an ideologically pure unit, is too much bother to write out.
Some do, some don't. I'm actually one of those "people". I didn't know what an inch was until the age of 26.

A lot depends on the context, material, country and tradition, even though Europeans will easily switch from one metric unit, or its representation, to another. My point was not the actual usage of the decimeter and I agree, it is not used as frequently in the context of volume as liter, but the usage is certainly not unknown (example below).

Decimeter is not as hard to write out either. How hard can it be to write dm3 for volume (where 3 is a superscript), or simply dm for length. A liter is not any more convenient than dm since both are exactly the same when it comes to volume.

Some practical examples of usage: if you or I buy a bottle of coke it will be either 335 ml, 1L or 2L. In some EU countries you can buy a quart/quarter of some fluid, i.e. 0.25 of a liter (a capacity of a standard glass/mug). That's for personal consumption. A major bar (I mean really major) may buy a few thousands of liters, or a few hectoliters (hl). When I had a Summer job in a winery and distillery all containers were marked in hectoliters. But when you buy a shot of vodka it's often in grams rather than milliliters (50 grams please) even if volume measuring cup is used instead of scales. The two are not 100% equivalent but close enough and after a few those fifties (1.7 fl.oz. straight as ice and such are for sissies) few could tell the difference anyway.

Concrete, even in the fluid form will be sold by cubic meters (m3) just like lumber. But when you buy a single board you will buy a single board of dimensions specified but your vendor bought it in cubic meters as a part of a larger shipment. However weird it may sound, from the point of view of your vendor he will sell you (as an example) 0.0039 m3 of wood, not 3.9 liters, or 3.9 decimeters or whatever the unit the buyer might consider more convenient.

In dry form, concrete and sand will be sold by kilograms (if bought as individual bags) or by tonnes (even if you order a truckload of individual bags). The water you add to it will be in liters or hectoliters and that will depend on the size of your job. If you pour concrete into forms to create cubes of 10x10x10cm you'll get 1 dm3 cubes (1 cubic decimeter), not 1 liter cubes, even though you use 1 liter of wet concrete.