Easy Metric Tutorial?

darita said:
Wow!  Lots of great info.  It looks like there's enough information here to do anything I need done.  I just have to study the posts.  And you're probably right about doing a project totally committed to metric.  I think that's the only way to really get used to using it.  Back to school...
I think what I'm going to have to do to start with, is to have a diagram showing an imperial foot below it's metric equivalent.  That way, I can visually relate the two.
Click to expand...

If you're going to read all this info back I'm sure you're not going to see the forest for the trees.

So in short, what you need to know for woodworking is meters, centimeters and millimeters.

m = meter
cm = centimeter
mm = millimeter

1 m = 100 cm
1 m = 1000 mm
1 cm = 10 mm

That's all you need to remember in relation to each other.

In relation to what you are used to now you need to remember:

1 inch = 25,4 mm or 2,54 cm
1 foot = 30 cm (30,48 if you're doing actual conversion calculations)

If you keep these things in mind you'll quickly understand metric for woodworking.
 
Alex said:
darita said:
Wow!  Lots of great info.  It looks like there's enough information here to do anything I need done.  I just have to study the posts.  And you're probably right about doing a project totally committed to metric.  I think that's the only way to really get used to using it.  Back to school...
I think what I'm going to have to do to start with, is to have a diagram showing an imperial foot below it's metric equivalent.  That way, I can visually relate the two.
Click to expand...

If you're going to read all this info back I'm sure you're not going to see the forest for the trees.

So in short, what you need to know for woodworking is meters, centimeters and millimeters.

m = meter
cm = centimeter
mm = millimeter

1 m = 100 cm
1 m = 1000 mm
1 cm = 10 mm

That's all you need to remember in relation to each other.

In relation to what you are used to now you need to remember:

1 inch = 25,4 mm or 2,54 cm
1 foot = 30 cm (30,48 if you're doing actual conversion calculations)

If you keep these things in mind you'll quickly understand metric for woodworking.
Click to expand...
Alex...thanks.  Exactly what I needed.
 
Paul G said:
T\not to say that .1nm is going to mess up your cabinets  [laughing]
Click to expand...

But it does for the microprocessors. memories, and all the other modern chips: the best manufacturing scale is now around 10nm !!  [eek]
 
greg mann said:
Rick Christopherson said:
As an engineer, I bounce back and forth between the two systems quite often. Many times even mixing the two within a single design. (However, drawings are always in one set or the other unless dual dimensions are given for when metric is required, such as screw threads. You never mix units unless there is some specific reason, and that includes the metric system too.)

The imperial system is not as bad as popular misconception portrays it. The main benefit of the metric system comes into play only when you need to convert units. If you don't need to convert units, that primary benefit is not terribly important. For example, converting cubic centimeters to liters is very simple, but that is not a conversion that the average person needs to do very often. Converting millimeters to meters is also very easy, but generally speaking, you still don't want to mix units, even when those units are just multiples of 10. Regardless which system you are using, you pick a unit and stick to it throughout.

The most common complaint about the imperial system is fractions. However, that is a "choice" not a "requirement". We "choose" to buy tape measures that are graduated in fractional increments. However, they are also available in decimal divisions too. That's not a fault of the system of measurement. It's just a choice that has been long-standing. Most machinists and engineers work in decimals, not fractions. And in that regard, there is no difference between the systems unless you want to convert to a different unit.

We "choose" to portray measurements in mixed units, such as 10' 3-1/4", as opposed to 123.25", but that is a choice, not a requirement. The same mixing of units could be done in the metric system, but it just isn't done. You will rarely see a mixed unit measurement of 1m 4cm 2mm. Instead, if the precision of millimeters is required, then the entire number is represented in millimeters (1042mm).

Neither system is any more accurate than the other. It is just different units.

Personally, I find it easier to "guesstimate" the length of a board in inches, than I could in centimeters. But that is simply due to familiarity, and the larger size of an inch versus a centimeter.
Click to expand...

Rick makes very good points here. To the OP my first thought in terms of advice is to get rid of the fractional calculator and start using decimals. Even if you go to metric at some point, thinking in terms of decimals will help in thinking metric. Rick's point about fractional measurement being a choice is spot on. Even though I use fractional tapes and scales , when I write down dimensions to do math I write them in decimal because the math is soooo much easier. Having been a machinist/manufacturing engineer all my life, and working in both systems pretty much in the manner Rick described above, makes it pretty easy to float back and forth between systems (and convert those pesky fraction into decimal values). Having said that, when my company first started in CNC machining I asked the question, "Which system should we program in?" The advice I was given was to program in the system in which you measure. It seemed like good advice at the time but I do wish I had been advised to, "Get rid of your Imperial measurement tools and do everything in metric."

Like Rick, the hardest part for me is visualizing sizes in metric over the values I use day to day. It is a piece of cake to work in sub-millimeter values as I do that all the time (.025mm, or 25 microns = .001" as an example,at least close enough even in my world). Centimeter callouts are more difficult for me as I feel the need to convert to millimeters before I can visualize that distance. It is getting easier as time goes by to visualize the macro distances butthe simple fact that I uses decimals in Imperial has probably kept me from changing over completely. Tht and the fact that most of the shorter measurements, say, under 12 inches, are pretty much automatic conversions for me anyway.
Click to expand...

"Back in the day" the company I was working for in preparing for EC'92 (remember that???) had meeting after meeting, hired consultants,  on and on trying to decide whether to go hard or soft metric across their product lines.  They went the way of some auto makers -- remember when you needed both sets of tools to work on your car?
I spent hundreds of thousands of dollars on training engineers, machinists and on precision measuring instruments.  It still ended up with engineers designing in imperial then flipping the switch to dimension their drawings in metric.  Then, I would walk around the shop and find machinists sitting at their workbench with a drawing & calculator converting everything back to imperial.   [scared]  Converting is where the devil lives and mistakes occur.
 
I grew up with both systems my father was a bricklayer (retired now at the ago of 72) and he used imperial and metric at work, imperial in his early career and later convered to metric, he was the first bricklayer in our county to lay a metric brick. he wanted me to be able to use both systems, I was taught metric at school, I use metric daily but on the odd occasions I do something for my father i use imperial.

As for units I find the CM totally pointless for carpentary, I find its used more Europe, I uses MM and M and occasionally down to half a MM. My apprentice was taught to use CM at college and I find it frustrating and am in the process of retraining him!

As for land I have always used acres and hectares, our roads are still in yards and miles.

Regards
Leigh
 
Paul G said:
Reiska said:
mhch said:
Decameter, hectometer, and kilometer are mostly used to express road distances and property dimensions.
Click to expand...

I'm sorry, but is this some weird kind of Frenchism? I've never ever seen deci-, deca- or hectometres used for anything else but irritating lower school kids in their math exams.

Area is measured only in square metres (m^2), volume is measured in either decilitres or litres for small quantities (up to a couple of hundred litres) or cubic metres (m^3) above that. One notable special case is car engine size that's usually expressed in litres i.e. a 1.8l engine, but in more exact technical terms it is expressed as cubic centimetres i.e. 1798cm^2 and lenght is measured in real life either in mm, cm, m or km.

Road distances are always in kilometres for longer distances and metres for less than a kilometre.
Click to expand...

It's kinda funny hearing a metric user say that certain types of metric is irritating.  Sounds like even there you stick with what is common (mm, cm, m or km) anything that deviates is irritating (dm, dam, hm) even though it only involves shifting a decimal. That's precisely why using metric here is irritating, it isn't common at all.
Click to expand...

I just wanted to point out that those are redundant and should not be pulled into the discussion of trying to help our fellow woodworker to learn to use metric to confuse things unnecessarily. It sort of like talking about those weird chains and furlongs about the imperial system that I presume are not used for anything anymore?

I think Alex's reply above summarizes this conversation perfectly to the point and I love NuggyBuggys more 'scientific' explanation as an engineer  [smile]
 
mhch said:
And also Pint was./is different between England, Scotland, Ireland (in increasing order of volume). There are still some British pubs displaying "here we served beer by the larger Scottish pint" !!
Maybe because some drink more than others .... [big grin] [big grin] [big grin] [big grin]
Click to expand...

Talking beer: generally the output of a brewery is reported in hectoliters  [big grin]
 
NERemodeling said:
coming from someone who doesn't use the metric system take this with a grain of salt  and correct me if im wrong guys,

one thing to remember when you are used to imperial but working in metric is not to get hung up on exact imperial to metric conversions, lets take a hypothetical side panel for a base cabinet (frameless)

in inches you would want to cut this to 24" wide x 34 1/2" tall

in metric that would be exactly 609.6mm x 876.3    -  trying to cut to this precision would be more frustrating that just sticking to imperial,

instead that same panel in metric would be cut to 610mm x 878mm

make the switch on a particular project, commit to metric and stick with it as bouncing between the two just dosesn't work

John
Click to expand...

To answer you this may help....

Our standard framing size is 70x35 mm or 90x35 mm
Minimum internal ceiling height is 2.4 meters (2400 mm)
Standard wall stud spacing is 450mm or 600mm
Our standard carcase melamine is 16mm (see the continuity here with "True 32" Euro cabinet spacing)
Our standard drywall is 10mm thick in a 1200x2400 sheet size and so on and on it goes...
Metric sized material is manufactured to a standard metric size that probably has no exact imperial equivalent.

If you have metric sized materials and you work to metric standard measurement, the work goes very well and no conversions are required or necessary...

One difference is plywood sheets that are often received sized at 2440 x 1220 mm (imperial?)

So, my point is nearly all 'standard' building materials are sized in whole metric sizing which makes the conversion of plans from imperial much more complex, because the standard material sizes will most likely be quite different.
If one is designing for metric it would be much more efficient to specify material on the plans to correctly match the actual material dimension, not some abstract figure that a conversion calculator spits out...

To try and convert an imperial plan to metric sizing and then try and build something to metric sizes using imperial sized material... Well that's enough to give me a headache just thinking about it....
Nope, I wouldn't even try and do it...
 
JoggleStick said:
NERemodeling said:
coming from someone who doesn't use the metric system take this with a grain of salt   and correct me if im wrong guys,

one thing to remember when you are used to imperial but working in metric is not to get hung up on exact imperial to metric conversions, lets take a hypothetical side panel for a base cabinet (frameless)

in inches you would want to cut this to 24" wide x 34 1/2" tall

in metric that would be exactly 609.6mm x 876.3     -   trying to cut to this precision would be more frustrating that just sticking to imperial,

instead that same panel in metric would be cut to 610mm x 878mm

make the switch on a particular project, commit to metric and stick with it as bouncing between the two just dosesn't work

John
Click to expand...

To answer you this may help....

Our standard framing size is 70x35 mm or 90x35 mm
Minimum internal ceiling height is 2.4 meters (2400 mm)
Standard wall stud spacing is 450mm or 600mm
Our standard carcase melamine is 16mm (see the continuity here with "True 32" Euro cabinet spacing)
Our standard drywall is 10mm thick in a 1200x2400 sheet size and so on and on it goes...
Metric sized material is manufactured to a standard metric size that probably has no exact imperial equivalent.

If you have metric sized materials and you work to metric standard measurement, the work goes very well and no conversions are required or necessary...

One difference is plywood sheets that are often received sized at 2440 x 1220 mm (imperial?)

So, my point is nearly all 'standard' building materials are sized in whole metric sizing which makes the conversion of plans from imperial much more complex, because the standard material sizes will most likely be quite different.
If one is designing for metric it would be much more efficient to specify material on the plans to correctly match the actual material dimension, not some abstract figure that a conversion calculator spits out...

To try and convert an imperial plan to metric sizing and then try and build something to metric sizes using imperial sized material... Well that's enough to give me a headache just thinking about it....
Nope, I wouldn't even try and do it...
Click to expand...

Yeh, for some strange reason most of our plywood is imperial. I'm guessing a lot is imported. I get mine here http://www.bruynzeel.com.au/plywoods.html ... notice the different sizes.
 
JoggleStick said:
NERemodeling said:
coming from someone who doesn't use the metric system take this with a grain of salt   and correct me if im wrong guys,

one thing to remember when you are used to imperial but working in metric is not to get hung up on exact imperial to metric conversions, lets take a hypothetical side panel for a base cabinet (frameless)

in inches you would want to cut this to 24" wide x 34 1/2" tall

in metric that would be exactly 609.6mm x 876.3     -   trying to cut to this precision would be more frustrating that just sticking to imperial,
[big grin]
instead that same panel in metric would be cut to 610mm x 878mm

make the switch on a particular project, commit to metric and stick with it as bouncing between the two just dosesn't work

John
Click to expand...

To answer you this may help....

Our standard framing size is 70x35 mm or 90x35 mm
Minimum internal ceiling height is 2.4 meters (2400 mm)
Standard wall stud spacing is 450mm or 600mm
Our standard carcase melamine is 16mm (see the continuity here with "True 32" Euro cabinet spacing)
Our standard drywall is 10mm thick in a 1200x2400 sheet size and so on and on it goes...
Metric sized material is manufactured to a standard metric size that probably has no exact imperial equivalent.

If you have metric sized materials and you work to metric standard measurement, the work goes very well and no conversions are required or necessary...

One difference is plywood sheets that are often received sized at 2440 x 1220 mm (imperial?)

So, my point is nearly all 'standard' building materials are sized in whole metric sizing which makes the conversion of plans from imperial much more complex, because the standard material sizes will most likely be quite different.
If one is designing for metric it would be much more efficient to specify material on the plans to correctly match the actual material dimension, not some abstract figure that a conversion calculator spits out...

To try and convert an imperial plan to metric sizing and then try and build something to metric sizes using imperial sized material... Well that's enough to give me a headache just thinking about it....
Nope, I wouldn't even try and do it...
Click to expand...

Great summery JoggleStick.

Another Australian exception like plywood is H4 laminated pine posts at approx and I mean  approx., 88x88mm or 3 15/32 inches and 112x112mm or 4 13/32 inches. (Nor fish nor fowl)

 
My apologies for reviving an old thread, but I'd just like to add a couple of things to make it easier to relate to metric measurements for those of you used to the imperial system.

Your fist is approximately 10cm.
A normal walking stride is approx one meter pr step.
Fingertips to center chest is approx one meter.

Naturally, this is rather rough and suited to a "normal" grown man, but it's a quick and simple thing to remember to do rough measurements without measuring tape. (like your thumb is an inch wide and so on)
 
tjt said:
Your fist is approximately 10cm.
A normal walking stride is approx one meter pr step.
Fingertips to center chest is approx one meter.
Click to expand...

Hmm, the metric system was designed specifically to avoid this way of thinking.  [unsure]
 
Alex said:
tjt said:
Your fist is approximately 10cm.
A normal walking stride is approx one meter pr step.
Fingertips to center chest is approx one meter.
Click to expand...

Hmm, the metric system was designed specifically to avoid this way of thinking.  [unsure]
Click to expand...

I was just thinking the same thing. If it works for you, more power to you. But this looks like a bad way to learn/approach metric. Do a youtube search. I'm sure you'll find something very useful there. After all metric is simplicity itself.
 
I havent read any charter or do's and dont's by the founders of the metric system, so i cannot confirm your statement.

I dont see the harm in beeing able to estimate the length of a rope by counting the number of pulls when holding one hand to your chest. I dont see the harm in estimating how long you threw a tennisball by counting the number of steps and converting it into an equal number of meters.

I see the benefit in having an intuitive way of estimating distances and sizes by using references you always carry with you. Whatever units you like to relate to.

The metric system is not negatively influenced by how you visualize common everyday objects. One meter is still defined by the length light travels in vacum in a 1/299792458 of a second. The definition is "pure". It is however of little value to you in practical use. Can you visualize this definition? Can you visualize the previous definition of a meter which was some fraction of the earths circumference?
A meter stick is much more useful even though is is an interpretation of the definition. Lacking a meter stick, there are still ways to estimate like i wrote earlier, even though it is a far cry from the SI definition.

I like to stay practical, and have a feeling for the measurements I use. Even though I am a scientist by training and profession and consider the metric system to be superior.

But, thats me :-)

So, my apologies for trying to relate metric measurements to some simple everyday things for the imperial folks.
I think the necessary introduction to the metric system had already been given in this thread. I would start out differently if I were to teach someone about SI from scratch if that was you points.
 
I agree with you TJT.

And most who have taught measurement as a concept to young children, as I have, would too.

Use of our body in measurement is a natural response to our environment. Our eyes, for example do it all the time, particularly when we move.

Measurement is of our environment, personal and beyond, it helps us to position ourselves in relation to each other and to objects, their size, comparative speed and capacity/volume. It is through recognition of measurement in our environment that we can estimate and compare.

"The rope is six of Susan's arm lengths long". "But Jack's arm is longer!" We can estimate then, but standard measurements such as metric allow us to more accurately communicate our environmental responses with each other, for example; when constructing a house.

And sometimes a rope length of six times Susan's arm length could be all that is required.

[wink]

 
This is interesting...

The Inch was originally defined in terms of the Barleycorn - 3 Barleycorn in an inch.  2.54 cm in an inch...  maybe the metric system is actually closer to the spirit of the "original" imperial system than most of us realized...  it's only really an 18.11% increase after all.

[laughing]
 
fdengel said:
This is interesting...

The Inch was originally defined in terms of the Barleycorn - 3 Barleycorn in an inch.  2.54 cm in an inch...  maybe the metric system is actually closer to the spirit of the "original" imperial system than most of us realized...  it's only really an 18.11% increase after all.

[laughing]
Click to expand...

I like to build cabinets 107 1/2 barleycorns (bc ?) tall  x 20" deep x 900 mm wide.  Its a lot of conversion  math , but I find they come out better that way.  ::)  [big grin]

Next time I am working  out a size with a customer I will have to ask them how many barleycorns wide they would like it.  And see if one cubit deep might be good.  [huh]

Seth
 
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