Metric or imperial - tempted to go retro

[woodbrains]

The reason is metric weights and measurements are not natural sizes nor do they fit in with nature.

Heavens!

What measurement is a natural size? Ever since humanity exists, up to the metric system virtualy every country, even virtualy every neighbouring people, had its own units, or its own values for same-named units. Talking of contemporaneous mesurements, what is more "natural" - the statute mile or the nautical mile? The avoirdupois ounce or the troy ounce? Etc.

As the designers of camouflaged clothing well know, there are no straight lines in nature. Why should we then design implements containing straight lines? They do not fit in with nature!!!

Come on; you only mean to say they don't fit in the British order of things - or, rather, what you wish were the British order of things.

deema, all your examples are British-centered! Which means totally biased. And speaking just of a fine drink, when I go for a beer I most certainly don't go for a pint, not here, nor in Spain, nor in France, nor in Germany or in Italy or any other country in Europe. Just in Britain. And besides nowhere else in Europe do people drink it disgustingly warm

Hello,

The point is, whether metric is a preferred system or not, it is not a human measure, it is purely a mathematically derived one. For instance the metre is defined as so many wavelengths of light in a vacuum. Don't know the exact number of wavelengths, or particular colour of light, but who cares, it is absolutely nothing we can relate to.

All the systems around the word were always based on something tangible, so had a lot in common with the imperial system. Of course Britain being an Empire once, the system was most common, but still based on the same human principle. For instance, the Roman mile was surprisingly similar to the mile we know today, 1000 strides. A Roman stride was about almost 6 feet. Funny that they chose 1000 which is a metric sort of number, when the Romans had their very strange number system, it probably did them no good for doing sums.

Mike.

 

[sdjp]

What measurement is a natural size?

There's a set of system of units often used by physicists called 'Natural Units'. http://en.wikipedia.org/wiki/Natural_units has a decent outline.

In these systems, the units are sized by taking various physical constants, and defining them to have a numerical value of 1. There's several systems, as there are too many such constants, so you can't get rid of all of them. One use of these systems is to make calculations similar by removing lots of constant factors, which makes it simpler to follow (and hence check) the algebra.

The one I'm most familiar with is the Plank units. In this the: speed of light; gravitational constant; reduced Planks constant and and Boltzman constant are all set to 1. Following through the algebra, and we can derive a conversion system to Plank units from other systems, using the values of those constants in those systems.

In this system, my smallest chisel is 3.7× 10^32 Plank lengths, which I often use in my workshop, which is typically a chilly 2.011 * 10^-30 Plank temperature. I'm hoping to get 4 * 10^47 Plank time in the shed at the weekend.

As you can see, 'Natural' in this sense isn't exactly 'convenient' for human scale operation. The difficulty with that is that the scale for human use varies - from a few mm up to km depending on the use case at hand, hence a factor of about a million for length. Workshop use gets that variation down from mm to metres, so about a thousand fold variation.

Claims about fractions and divisors I really can't see being all that relevant over that much variation - unless your just needing approximate measurements, in which case precise divisions don't matter. If you can control the size of things, then 24 millimetres is highly divisible, and very close to an inch. If you can't control the size … then surely the divisibility of units doesn't help?

As I said earlier, I can (and have) used inches before. And Rankine for temperature. And mmHg for pressure. And several others - but when I get the opportunity to choose, I'll pick SI units (or whimsically obscure metric not-strictly-SI units upon occasion).

 

[GLFaria]

This thread is becoming more and more similar to a thread on sharpening! :lol: :lol: :lol:

 

[woodfarmer]

The reason is metric weights and measurements are not natural sizes nor do they fit in with nature.

Heavens!

What measurement is a natural size? Ever since humanity exists, up to the metric system virtualy every country, even virtualy every neighbouring people, had its own units, or its own values for same-named units. Talking of contemporaneous mesurements, what is more "natural" - the statute mile or the nautical mile? The avoirdupois ounce or the troy ounce? Etc.

As the designers of camouflaged clothing well know, there are no straight lines in nature. Why should we then design implements containing straight lines? They do not fit in with nature!!!

Come on; you only mean to say they don't fit in the British order of things - or, rather, what you wish were the British order of things.

deema, all your examples are British-centered! Which means totally biased. And speaking just of a fine drink, when I go for a beer I most certainly don't go for a pint, not here, nor in Spain, nor in France, nor in Germany or in Italy or any other country in Europe. Just in Britain. And besides nowhere else in Europe do people drink it disgustingly warm

The nautical mile is in fact I think 1 second of arc on the earth and was used for navigation. Now I know Britain rules the waves, or at least did, but I don't think it can claim the earth was built to fit in with the nautical mile, it is the other way around. hence the nautical mile is a relevant to nature distance.

re the different ounces, it makes sense to use different units of measurement when weighing gold or turnips. again it is a question of scale.

 

[sdjp]

The point is, whether metric is a preferred system or not, it is not a human measure, it is purely a mathematically derived one. For instance the metre is defined as so many wavelengths of light in a vacuum. Don't know the exact number of wavelengths, or particular colour of light, but who cares, it is absolutely nothing we can relate to.

It's not actually; not since 1983. The definition you're thinking of was "1650763.73 wavelengths in a vacuum of the radiation corresponding to the transition between the 2p10 and 5d5 quantum levels of the krypton-86 atom." - which is an orange-red colour, if you're less familiar with the orbital energies of the noble gasses.

Since 1983, the second is defined as "The duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom." The speed of light is then defined to a particular speed, and the metre is then a _derived_ unit.

This is clearly nothing that we can relate to, as it's just a mathema… oh, wait, that's the _same_ second that everyone uses. It gets this rather precise definition purely because we can _measure_ that to absurd levels of precision. Indeed, we can actually measure time more precisely than distance, hence the choice was made to make distance the derived value.

The _size_ of the second has very little to do with the way it has been defined. Likewise the definition of the metre had little to do with the actual length. The original definition of the metre was "1/10000000 of the meridian through Paris between the North Pole and the Equator" - i.e it was a particular fraction of the circumference of the earth [0]. That particular fraction was chosen to be the closest 'simplest' fraction to a yard! So it's not surprising that a metre is similar to a yard.

I think you're confusing the extremely precise _defintion_ of the units with the _size_ of them. The size was mostly picked to be human scale - that's why the standard is the kilogram, not the gram (too small). The definitions are picked to be whatever we can do to the highest accuracy, which has, of course, changed over time.

If you think inches and yards are superior to metres, purely on the basis of the definition, I'm going to have to ask you what the definition of the inch (or foot, or yard) is? The relationship between them is clear, but it's the definition that would be used when you have two 'yard' sticks of different sizes, to determine which is correct. (Given the setup, it won't surprise you that it's defined in *exactly the same way*).

[0] It's not though - there were measurement errors, and it was originally done through a 'standard metre', the same way the kilogram currently is, and with the same attendant problems. Still, that was the intent.

 

[AndyNC]

Hi,

sdjp: Thank you fir that most illuminating post.

I think what I had in mind is that the Centimetere is not an engineering unit and causes me the most difficulty when reading a mixed unit tap measure.

Don't forget there are approximately Pi seconds in a nano century and light travel at approx 1ft per nanosecond. Can't remember if that's in free space or not.

Also I believe the Taiwanese foot is divided in to 10" and is nearly the same length as an English foot.

Cheers

Andy

 

[Random Orbital Bob]

I think you all need to get out more!

 

[AndyT]

I think the suggestion that units of measurement need to be related to something on a human scale is a sound one.

Think about weight for example. All over the world, every day, people buy food by weight. If you are buying apples or onions or sausages, the most natural unit is the amount you can comfortably hold in one hand. So it's no surprise to find that most countries have a unit of about that size.

We have the pound. In France they still use the livre. (You will get 500 grammes - but it is simple and natural to have a one word unit, and count in small numbers.)

In Italy, Spain or Portugal you would ask for a libra.
In Russia, a funt.
In Holland, a pond.
In Japan, a kin.
In Thailand, a catty.

The pattern is clear. Even where official measurements are the metric system, informal units persist as a more natural way to talk about quantity. Sometimes they survive in name only, with the underlying definition being a round number in metric, but the need for a natural unit is very widespread.

 

[bugbear]

When you have something specified in a unit, you expect the size to be accurate to one unit, but wood specified in millimetres is often several units of measurement wrong. This is because the unit is too small for natural usage.

Good rant! Approved.

But the point I've edited out won't stand. How do you explain a good, simple American 2x4 being so far away 2 inches and 4 inches?

BugBear

 

[Rhossydd]

1/4" & 1/2" router bits all appearing standards

Just because there are two imperial standards for router shank size, doesn't mean that the router bits you buy will have imperial cutters. There's an important difference there.
There's pretty much only one company in the UK (Rutlands*) selling imported imperial router cutters, the other major manufacturers Trend & Wealdon both quote cutter sizes in metric, as do most of the other cheap imports that you might just buy as disposable for a single job.
The cheap 12" dovetail jigs are all pretty rubbish and not nearly as much use as you might think, so don't place too much on their length being imperial either. The best of the dovetail router jigs is the(Canadian) Leigh ones and they come in both metric and imperial and use 8mm shank cutters, figure that one out.

I'd like to just stay 100% pure metric but for the reasons I just mentioned that would seem to involve a constant "struggle" against many tools and tutorials out there. Since I get to measure and cut my own timber, set my own router and table saw etc it strikes me I could easily decide right now before embarking on any major projects to work in imperial only.

That doesn't quite add up does it ? The actuality is that most tools and materials available in the UK are metric sized now, so sticking to metric makes more sense, especially since you've said you can work in either.
Are you really likely to just build American projects ? One of the joys of DIY is the ability to make things to suit oneself and not be constrained by other people's ideas and dimensions.

I think the consensus here has been that those of us over a certain age tend to think in big approximate imperial measurements the table about six feet long, a shelf six inches deep etc. Then swap to metric for actual precise measurements. I think because the millimetre is a convenient length of precision in woodworking, each division on scale is distinct enough whilst still being fine enough. Whereas 1/16th is a little coarser and 1/32 just starts to get too small to read easily off a scale.
If you're the sort of person that's very comfortable with fractions, imperial may suit you better of course.

*As a novice you need to beware of one supplier (Rutlands) influencing what you buy. Just because they have a glossy web site and seem to offer bargains occasionally, doesn't mean it's wise to buy too deeply into their imported imperial goods. It's no fun to find that a year or two down the line getting replacement parts is much harder because almost every thread on European part(threads, mitre slots etc) is metric and nothing easily and cheaply available fits.

 

[Random Orbital Bob]

Well that's simple...they're American! Obviously it should be 4x2, that would then be perfectly in balance and whilst totally failing to satisfy the logic of your point, still somehow, correct

Referring to Bugbears post of course not Ross's (which was exactly what I was thinking incidentally so jolly well put)

 

[Racers]

Its 2x4 sawn and then plained.

Pete

 

[Tony Spear]

Its 2x4 sawn and then plained.

Pete

And then after planing it turns out as roughly 44mm x 94mm! :roll:

If you go into a timber merchant and ask for 2x4 PAR "planed all round" you'll get what I've said above.

If on the other hand you really need it finished at 2x4 it will be planed from something larger!

 

[Random Orbital Bob]

we always used to call that ex 4x2.

 

[richarnold]

I'm confused. Doesn't anyone in the trade still work to good old fashioned measurements like "a gnats cock" or "just a smidgin". :wink:
On a more serious note, I do still use imperial measurement's for most of my work, and rather than use 1/32. things get described as "full or bare". a lot of the jobs are measured up with a rod which never lies, and can't be written down wrong. I'm sure I'm heavily influenced by the guys I was apprenticed to, but a lot of the traditional joinery still works well in imperial. I have always cut single glazed rebates to 5/16. this leaves a nice even 1/8 between on a 3/4 bar. None of these measurement's work well in metric.

 

[deema]

Talking of a gnats cock, sorry about the connection, and lowering the tone but could you ever imagine anyone claiming to be more than 152.4mm? :lol:

 

[woodbrains]

It's not actually; not since 1983. The definition you're thinking of was "1650763.73 wavelengths in a vacuum of the radiation corresponding to the transition between the 2p10 and 5d5 quantum levels of the krypton-86 atom." - which is an orange-red colour, if you're less familiar with the orbital energies of the noble gasses.

Since 1983, the second is defined as "The duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom." The speed of light is then defined to a particular speed, and the metre is then a _derived_ unit.

This is clearly nothing that we can relate to, as it's just a mathema… oh, wait, that's the _same_ second that everyone uses. It gets this rather precise definition purely because we can _measure_ that to absurd levels of precision. Indeed, we can actually measure time more precisely than distance, hence the choice was made to make distance the derived value.

The _size_ of the second has very little to do with the way it has been defined. Likewise the definition of the metre had little to do with the actual length. The original definition of the metre was "1/10000000 of the meridian through Paris between the North Pole and the Equator" - i.e it was a particular fraction of the circumference of the earth [0]. That particular fraction was chosen to be the closest 'simplest' fraction to a yard! So it's not surprising that a metre is similar to a yard[/quote]

Hello,

I understand what you mean, I realise there has to be a way of standardising a thing. However, even the original definition of the metre has nothing much to do with anything tangible and its sub divisions even less. It is not convenient having to measure almost anything in mm even if it is a house, because the subdivisions have been mathematically decided, rather than practically arrived at. Most, if not all older measuring systems come from Vitruvian proportions.

Regarding what are natural measurements;
3 barley corns = 1inch
3 inches = 1 palm.
4 inches = 1 hand.
9 inches = 1 span.
12 inches= 1 foot.

1 yard is exacly divisible by all these and 1 yard is an average pace, or arms length.

The really sad thing is, I didn't have to look these up!

Mike.

 

[Phil Pascoe]

I'm 60 and came across a school excercise book from when I was about eight. In it were sums done in pounds, shillings, pence and farthings, and also furlongs, chains, rods, poles and perches. Pecks and bushells were easy after that. We also bought our potatoes in gallons.

 

[JustBen]

If you're discussing measurements, don't forget tyre measurements........ Metric/ Percentage/ Imperial

 

[woodfarmer]

When you have something specified in a unit, you expect the size to be accurate to one unit, but wood specified in millimetres is often several units of measurement wrong. This is because the unit is too small for natural usage.

Good rant! Approved.

But the point I've edited out won't stand. How do you explain a good, simple American 2x4 being so far away 2 inches and 4 inches?

BugBear

What they will tell you is that is the size of the wood before it was cut, what's missing is the thickness of the blade.
To discourage this scam pay them with your wages before tax and NI has been taken out, and deduct those from the payment.. see how they like that