Since when did 3/8" = 9.2mm?

I have a metric brain.
I was in primary school when Aus went metric and for me, it was a very welcome change, the logic of it was obvious.
My Dad was a carpenter and he would speak both languages at once, "can you pass me a 2.4 of 4x2."

In 1981 I was an exchange student to a suburb of Chicago. There was a road nearby that had a sign "Metric sign trials. This road will display speed limits in Km/h for the next 100 miles."
 
fritzelhund said:
Some years ago owned a VS Commodore, the V6 engines needed regular water pump replacements , probably due to the extreme tension on the huge ( 8 feet ??? ) serpentine belt. These engines started life as Buick products in the US of A, but by VS Commodore times were built in OZ. The water pump fasteners were still imperial while the rest of the engine was metric.
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My brother had a 1963 Nissan Cedric. Every bolt on the engine was imperial, every other bolt on the car was metric, even the bellhousing bolts. Engine was a BMC copy of course.
 
A few random comments
I noticed that Bunnings started carrying alot more construction bolts and nuts in metric, rather than imperial, several years back. Took a while. I would think the 'problem' lies not with manufacturers - who after all, make fasteners in both measurement systems - but with the wholesalers and retailers who buy them.

As I understand it, "the metric system" and "the SI system" are for all practical purposes, the same thing. There seem to have been a number of metric systems ie based on 10s, and the SI system is The metric system in use today.

Girls tend to use cm where there better halves use mm, because they don't typically have things cut to size, and have therefore never had the experience of asking for something to be cut to size, and stating cm, then turning up and finding them one tenth the expected size. They are rarely are involved in buying or using engineered metal items where these small measurements become important.

Re advertising, it seems the restriction is that metric units must for goods sold where measurement determines price.
So Bunnings can legally sell imperial bolts and JB Hifi can legally sell tvs by their size in inches.

I have found that some 'standard sheets' are 2400 x 1200, and others are 2440 x 1220, the latter being 8' x 4'.
 
Metric is a vague term and refers in a general way to the measurements used in France and other European countries in times past. Australia adopted the SI Système international.

SI on the other hand is quite specific, based on defined metre, kilogram, second, ampere, kelvin, mole, candela (hence an MKS system).

Centimetres and many traditional others from Europe don't have a place in SI, though there is provision for derived units (eg Newton, radian) and permitted units (eg hour, degree).

The MKS system for technical use goes back to the 19th century, but it was never customarily used in European households.

Imperial is only metric in the sense that the units have been converted and legislately redefined in SI units for scientific consistency. Sometimes traditional units are so useful, they have been metricated, the French tonne, once a barrel full, became 1000 kg,
 
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My old Citroen is doing nearly 400 leagues to the firkin. I reckon that's pretty good on modern petroleum 😉
 
Assuming you mean the beer firkin, that's 3.4 litres per 100 km. Not bad for an old Cit.
 
seasink said:
Assuming you mean the beer firkin, that's 3.4 litres per 100 km. Not bad for an old Cit.
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Gosh I wouldn't be skiting about the fuel consumption if it was a wine firkin! Mind you I was driving for economy, average speed:
12 Iieue de Paris per hour.👍
 
A.k.a lieue des Ponts et des Chaussées. Now in real Londres money that's 29 mph.
 
seasink said:
A.k.a lieue des Ponts et des Chaussées. Now in real Londres money that's 29 mph.
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Correct, bit too long to print on the the speedo face though and the "Paris" version adds a little "je ne sais quoi" for the foreign market.
I'd always wondered why they were called D Specials.🤔
 
To regress a bit to thousandths of an inch - When asked how many thousandths there were in an inch, a friend of mine always used to reply :- Gee, there must be millions of the bastards"!
 
The same fellow, when asked by his mother to fix her wobbly (wooden) fence, replied that he'd attend to it just as soon as he could find some oregon electrodes for his welder!
 
seasink said:
Centimetres and many traditional others from Europe don't have a place in SI, though there is provision for derived units (eg Newton, radian) and permitted units (eg hour, degree).
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on this point, surely once the 'metre' is an SI unit, any prefix to multiply or divide it by multiples of 10, is 'correct'?

I think 'the metric system' really is just the man-in-the-street way of referring to the system 'we' use ie the SI system.
 
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59 Floride said:
Americans could easily feel better about their weight simply by switching to metric.
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Your assumption is that they want the number to be smaller. I thought they were aiming for bigger numbers.
 
Ren, the "magic number" for multiples in the SI system isn't 10, it's 1000. Hence mg, g, kg; mm, m, km; and so on.

No centi--s, no deci---s.
 
That was the feeling of the French revolutionary times when metric was created, but is not the basis of SI.

Those who can remember all the debates and lectures given to technical workers at the time of conversion will remember this. The multiple used is 1000. That is why centimetres decimetres and others are not used in the SI system.

It was rammed into us in the late 60's by the metric enthusiasts when conversion began.

Buildings are measured in millimetres, engineers work in kilopascals, and so on.
 
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seasink said:
That was the feeling of the French revolutionary times when metric was created, but is not the basis of SI.

Those who can remember all the debates and lectures given to technical workers at the time of conversion will remember this. The multiple used is 1000. That is why centimetres decimetres and others are not used in the SI system.

It was rammed into us in the late 60's by the metric enthusiasts when conversion began.

Buildings are measured in millimetres, engineers work in kilopascals, and so on.
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Correct, and air pressure is quoted in hectopascals.

Centimeters etc are indeed part of the metric system, but are not SI units.
 
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