Woodworking measuring units

[MooreToolsPlease]

one fella I worked with a while ago used both...
its quite difficult cutting a piece to 24inches and 5 mil :lol:

 

[Steve Maskery]

I've never managed to find an adhesive scale in metric and imperial with 0 at the right hand end - imperial only is no problem.

Yes, rare, aren't they. But they do exist. I bought a couple from Uppertown Tools in Bakewell, Derbyshire. I don't think they do MO though.

Alternatively try Peter at The ToolPost. He sells a tape measure that reads R->L, you could use that and stick it on yourself (well, on the jig - you know what I mean).

 

[wrightclan]

I can work in both, and convert quite quickly from one to the other. But Imperial immediately means something to me; whereas metric, I have to think for a second to visualise what a measurement means. I think thats what Niki was referring to, although he was comparing cm to mm. That's also something Bob of Bobsrule alludes to in his spiel.


When you're talking about a project with numerous measurements and dimensions, I will intuitively pick up a problem with imperial measurements; whereas with metric, I may not pick up the problem until I have started cutting/assembling.

Not an old geezer--just a backward Yank. :roll:

Brad

 

[DomValente]

Hey Scrit, I thought 20 bob made a pound.

In Italy they use a measurement called Polici which is equal to one inch and is used exclusively in plumbing.

My favourite gripe happened when I first encountered cubic metres in timber, I had always ordered in cubic feet and suddenly this demon appeared. One day I arrived at the timber yard all measurements at the ready and was informed that the number of cubic feet I wanted was now one and a half cubic metres,Ok says I."I'll just repeat that then "Said the salesman," one and a half cubic metres European oak of six by two :evil: :evil: :evil:

Dom

 

[Roy Clarke]

Just had to reply to this one. I don't see what all the problem is :wink:, I grew up with OO gauge model railways, scale 4mm=1 foot. Would have been nicer with TT gauge (3mm=1 foot).

The stupidity of the prescribed metric system of having a unit of a metre is sort of ok, but then using a multiplier of 1000 to get mm or km is not easy to model in most peoples heads.

 

[Jhalfa]

I'm sure that I hear somewhere that one of the problems with the first shuttle disaster was that some subcontractors were using CMs and other were using Inches. The combination can be quite dangerous in engineering.

I work for an American company, and when I tell colleagues over the pond that I lost 3 stone this year, they look at me as if I am talking gibberish. They say that it has been 30 degrees in New York and it takes a while for me to work out that it is cold!

 

[George_N]

I think its because centimetres don't technically exist. SI units are the mm and then the metre. The cm is a made up unit not an SI unit.

Its what you get used to, I now think totally in mm's and just can't fathom some of the older boys I know talking in 37/64th's, even clients who talk in cm's seems odd.

The base SI unit of length is the metre and shorter lengths can be prefixed with deci (1/10), centi (1/100), milli (1/1000), micro (1/10,000), nano (1/100,000)...all the way down to yocto at 10 to the minus 24, so centimetre is a legitimate SI unit defined as 1/100th of a metre. (note to self...switch off pedant mode).

 

[Jhalfa]

The metre is not a made up unit, granted that it's definition is slightly arcane:

"The origins of the meter go back to at least the 18th century. At that time, there were two competing approaches to the definition of a standard unit of length. Some suggested defining the meter as the length of a pendulum having a half-period of one second; others suggested defining the meter as one ten-millionth of the length of the earth's meridian along a quadrant (one fourth the circumference of the earth). In 1791, soon after the French Revolution, the French Academy of Sciences chose the meridian definition over the pendulum definition because the force of gravity varies slightly over the surface of the earth, affecting the period of the pendulum.

Thus, the meter was intended to equal 10-7 or one ten-millionth of the length of the meridian through Paris from pole to the equator. However, the first prototype was short by 0.2 millimeters because researchers miscalculated the flattening of the earth due to its rotation. Still this length became the standard. In 1889, a new international prototype was made of an alloy of platinum with 10 percent iridium, to within 0.0001, that was to be measured at the melting point of ice. In 1927, the meter was more precisely defined as the distance, at 0°, between the axes of the two central lines marked on the bar of platinum-iridium kept at the BIPM, and declared Prototype of the meter by the 1st CGPM, this bar being subject to standard atmospheric pressure and supported on two cylinders of at least one centimeter diameter, symmetrically placed in the same horizontal plane at a distance of 571 mm from each other.

The 1889 definition of the meter, based upon the artifact international prototype of platinum-iridium, was replaced by the CGPM in 1960 using a definition based upon a wavelength of krypton-86 radiation. This definition was adopted in order to reduce the uncertainty with which the meter may be realized. In turn, to further reduce the uncertainty, in 1983 the CGPM replaced this latter definition by the following definition:

The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.

Note that the effect of this definition is to fix the speed of light in vacuum at exactly 299 792 458 m•s-1. The original international prototype of the meter, which was sanctioned by the 1st CGPM in 1889, is still kept at the BIPM under the conditions specified in 1889."

 

[Niki]

I use cm's just because that's what I see on my rulers and measuring tapes and I just write the numbers like 23.4 or 0.4 (and if I'll tell my wife 1483 mm, she will chuck me from the house...)

I have one ruler of 1 Metre (Ooops...1,000 mm), graduated in mm, I mean the numbers...but I still read it as cm's.

As an x-aviation person, I'm used to both Metric and Imperial but it's like two deferent languages...very difficult to translate exactly.

I remember that in Israel, the Jet fuel was supplied by Imperial Gallons but the airplane fuel gauges were reading in Kilograms but then, in USA the fuel was supplied in US Gallons....and on that we were saying "why to make it simple, if you can make it complicated"...

niki

 

[Pekka Huhta]

At first I was going to argue against using centimetres, but then again, it's just what I do when I come to think that.

It depends. At work (metalworking industry) I use mm only. When I design something for the house or a piece of furniture, I still use mm, but end up building it in centimetres. When actually building something without plans I generally use cm, but if the last millimetres are important (on house-scale jobs they seldom are) I mark it up in mm. On the other hand I really had to think it hard, as I do the conversion without even giving it a thought.

But, as Finland has been metric since 1887, there shouldn't be any reason for me to use imperial measurements. Still, a two-by-four is a two-by-four, a 18x100mm board is a "three quarter board" etc. Old habits die slow and as I've been taught by the old school guys who used these.

So if you think that you all should be converted to using SI system in 30 years, you'll be hanging to those old measurements still at 2107

The lapps (living in Lappland) regularly use a distance called "poronkusema". It means the distance you can travel with a sled driven by a single reindeer before it has to stop for a pee. A reindeer can't do it running, so if you don't have a pee break every 5-7 km, it will get some sort of a seizure. And this story is true

Pekka

P.S, Scrit mentioned about the "duim" (pronounced dow-m) in Netherlands. Over here inch is called "tuuma" which would be pronounced too-ma, with the same linguistic background in them. In the scandinavian languages inch is a tom, tomme or tomma, which is of the same origin as tumme, (=thumb), so it's probably some kind of a viking invention again, the whole inch business :wink:

 

[engineer one]

but if we go really si units all the wonderful old phrases like

"inching a long"

"a short inch or a long foot"

will have to be replaced.

any guesses about the approved euro standard for these :twisted:

will there be an health and safety document to provide us with the correct terminology?? :lol:

as pekka says we have alot to blame the vikings for
including cutting off your nose to spite your face :?

paul :wink:

 

[Another Dave]

I see on the BBC site that the EC have apparently given up on trying to convert us Brits to metric. About time too!

http://news.bbc.co.uk/2/hi/uk_news/6988521.stm

As regards the centimeter, I remember something along the lines of it not being a 'recognised' unit in the 'official' metric system, the Systeme International d'Unites - millimeters, meters, and kilometers are the accepted units - but school was many years ago.

Now where did I put that foot-rule, and the three-pound hammer ..............

 

[brianhabby]

Hi there,

I remember reading in one of Norm's books that it's better not to measure at all - and his motto 'measure twice, cut once'

He was referring to the idea of marking a piece by lining it up with where it is to go and that has got to be better than trying to transfer confusing numbers. Not always possible of course.

I regularly mix both metric and imperial depending on my mood at the time but much prefer to think in inches. I just measured for some decking and got a funny look from the lad in the yard when I asked for a piece 193 inches long!

Nice to see that the Eurocrats have finally given up on us :lol: :lol: :lol:

regards

Brian

 

[keithhickson]

I remember being very confused trying to work out the size of carpet I needed as I had to take the width (loom width was I believe 13') and order in metres for the length

 

[newt]

I was brought up on imperial, had to convert to SI because of military aviation (glad I did). Most model engineering plans are still in fractions, although I think this is changing. By the way a useless piece of info, the period of a pendulum the radius of the earth is 84 minutes, major parameter in inertial systems.

 

[johnjin]

This is all very well but where does the humble measurment of a gnat's cock fit into all this.

All the best

John

 

[DomValente]

Or a hairs breadth

 

[keithhickson]

ccasion5: ccasion5: ccasion5: ccasion5: ccasion5: ccasion5:

 

[Paul Chapman]

Has anyone yet worked out how long a piece of string is :? :? :?

Cheers :wink:

Paul

 

[DomValente]

Yes, I believe that it was agreed that it should be the distance from earth to the moon.

Dom