What is the purpose of two units of mass in the Imperial system?

[diogenesNY]

I remember way back in second grade (circa 1973) posters on the classroom wall, with various illustrations and conversions, proudly proclaiming: "America's Going Metric!"

 

[Hornbein]

I remember way back in second grade (circa 1973) posters on the classroom wall, with various illustrations and conversions, proudly proclaiming: "America's Going Metric!"

I remember it was scheduled for 1980.

 

[Vanadium 50]

The metric system is, and has been for some time, the preferred (and in some cases, only) legal standard in the US. It still hasn't completely caught on, with exceptions like 2 liter bottles, and 10 mg pills.

But what do you do to fix it? Criminalize the use of feet and pounds? "What are you in for?" "Murder - and you?" "I bough a pint of milk." "A pint! You fiend!"

 

[Baluncore]

But what do you do to fix it? Criminalize the use of feet and pounds?

It was once an offence to carry a tape measure onto a building site in Australia, if that tape was graduated in centimetres.

In Australia, it only took two years from 1974 to 1976, to convert the building industry from feet, inches, and fractions of an inch, to metric.

Australian linear measures must be graduated in millimetres and metres, because then, decimal points and fractions are not needed anywhere in the building industry. Builders only need to do integer arithmetic. Wastage of materials and time has been significantly reduced, resulting in savings that have been growing and compounding now for 50 years.

The thing keeping the US back, is their comedic addiction to customary units.
Long may we benefit from US intransigence.

https://themetricmaven.com/building-a-metric-shed/

 

[sophiecentaur]

It was once an offence to carry a tape measure onto a building site in Australia, if that tape was graduated in centimetres.

In Australia, it only took two years from 1974 to 1976, to convert the building industry from feet, inches, and fractions of an inch, to metric.

Australian linear measures must be graduated in millimetres and metres, because then, decimal points and fractions are not needed anywhere in the building industry. Builders only need to do integer arithmetic. Wastage of materials and time has been significantly reduced, resulting in savings that have been growing and compounding now for 50 years.

The thing keeping the US back, is their comedic addiction to customary units.
Long may we benefit from US intransigence.

https://themetricmaven.com/building-a-metric-shed/

The Australians can cope very well with change. Not long ago they went for a gun law which produced instant reduction in deaths and injuries; no fuss, they just did it.
Their good attitude to regularising the measurement system doesn't surprise me at all.

their comedic addiction to customary units.

There are many "comedic addictions" in the US. Guns and aged politicians are just two more examples. (I DO NOT have a problem with my memory!) What staggers me is the huge number of lovely, pleasant and balanced individuals over there. Pretty clever too!

 

[JT Smith]

Cost-benefit analysis for adopting the metric system cold turkey probably does not favor the adoption -- in the U.S. A small country like Australia (13M in the 1970s) probably had a lot to gain. It more or less had to change. The U.S. doesn't have to change.

For the average citizen it would be a PITA. For industry it would result in significant cost. The long term benefit? Maybe not as much as people imagine. And the old system wouldn't simply go away in a couple of years.

I had always been a little embarrassed that the U.S. never made the full switch. But now I'm not so sure how important it really is.

 

[sophiecentaur]

I had always been a little embarrassed that the U.S. never made the full switch. But now I'm not so sure how important it really is.

It just costs a steady drip drip of money and risk by not choosing to get in line.

 

[Baluncore]

For the average citizen it would be a PITA. For industry it would result in significant cost. The long term benefit? Maybe not as much as people imagine. And the old system wouldn't simply go away in a couple of years.

Said like a true addict. It will cost votes.

The aim is not to eliminate the old system, but to formalise the new.
The size of the country is irrelevant. Big countries make bigger savings.

The size of the industry is irrelevant. Big industries make bigger savings.
The automotive industry, in the US, left the US behind in the late 1970s.

The significant cost is not in changing, it is in not changing.

 

[sophiecentaur]

For the average citizen it would be a PITA.

It would be no worse than learning to use a smart phone or drive a Zoom connection. There's a very sad rump of reaction against decimal in UK. There are even some politicians who promise to allow imperial units for food sales.
The 'average citizen' is well capable of this stuff when they have no option. It makes me cross (you may have noticed).

 

[JT Smith]

Said like a true addict. It will cost votes.

You mean me? I use the metric system every day. But I also think that the old system works just fine for some things. The metric system as a panacea is a kind of groupthink.

I believe that the main reason for the U.S. not changing is about money. If there were money to be made by changing there would be change.

 

[gmax137]

. It makes me cross

To me, it's like being upset with those French people. You know, they have a different word for everything.

 

[sophiecentaur]

To me, it's like being upset with those French people. You know, they have a different word for everything.

Except the French have an interesting language and culture which is worth getting into. Is there anything at all interesting about 17/32"??

 

[Baluncore]

Is there anything at all interesting about 17/32"?

13.5mm is about 17/32"

 

[gmax137]

Is there anything at all interesting about 17/32"??

Ha ha. I have these in my box, I'm sure I never used them.

This one I have used.

 

[jack action]

Ha ha. I have these in my box, I'm sure I never used them.
View attachment 340101

This one I have used.
View attachment 340102

BSF? Best Spanner Forever?

 

[gmax137]

https://en.wikipedia.org/wiki/British_Standard_Whitworth

More than most people ever wanted to know. Although Whitworth threads are long out of fashion, Mr. Whitworth is the guy who really led the charge on standardizing thread forms.

 

[Baluncore]

BSF? Best Spanner Forever?

British Standard Whitworth = BSW, standardised threads at 55°. Later, when metallurgy and machining tolerances improved, there was British Standard Fine = BSF, also 55°. The Whitworth spanners were marked for the size of the thread = the diameter of the bolt. That worked OK when Whitworth was the one and only standard.

60° UNC and UNF threads appeared in the US, then migrated to the UK during WW2. Obviously, the 55° BSW and BSF threads mismatched the 60° UNC and UNF threads. There were also a 60° BSC = British Standard Cycle thread, and (metric) 47.5° BA = British Association (of Engineers) standard threads.

With so many thread standards, a spanner in the UK, (wrench in the US), (key = clé in France), (key = schlüssel in Germany), (key = chiave in Italy), are now all specified Across the Flats = AF.
Some British spanners during the transition were marked with AF, as say 1/2"AF, to distinguish them from 1/2"BSW, or 1/2"BSF, but are now simply marked 1/2".

Standardisation has reduced costs and employment.
The number of inventory items that must be kept in stock as spares will fall gradually as old stock is used or scrapped.

I need a LH 1-1/4" BSF nut to repair an old saw bench. They used to be a commodity, but I could not find one available anywhere. It is not easy to cut left-handed internal threads in an old engine lathe, because the start of the cut cannot be seen.

 

[Ranger Mike]

And to complete this discussion:

View attachment 339508

Subway refuses to answer my questions about whether it's an International Footlong or a US Survey Footlong. A milligram of sandwich is at stake!​

good show

 

[Nik_2213]

If you hunt around, there are real-neat 'Metrinch' spanners that have a sorta-crinkly jaw that grips both eg 3/8" and 10mm 'Across Flats'. Also, they'll usually grip fixing that was one of those before 'wear, tear & rust'...

Tangential: Any-one ever seen an Octal slide-rule ? Or how to craft such ??

 

[Baluncore]

Octal-Decimal slide rule calculator.
https://www.computerhistory.org/collections/catalog/X585.85

https://treasures.scss.tcd.ie/sliderule/Slide_Rules_for_Computer_Programmers_updated.pdf

 

[sophiecentaur]

If you hunt around, there are real-neat 'Metrinch' spanners that have a sorta-crinkly jaw that grips both eg 3/8" and 10mm 'Across Flats'. Also, they'll usually grip fixing that was one of those before 'wear, tear & rust'...

Tangential: Any-one ever seen an Octal slide-rule ? Or how to craft such ??

I bought a 1" / metric equivalent a while ago. It cost a lot but it did the job (strong enough and a good fit when the right way round. It's in a box somewhere but I haven't needed it for a long time.

 

[Nik_2213]

My pair of 3/8"-10mm 'Metrinch' spanners came into their own assembling several flat-pack workshop-type trolleys. The many M6 nuts / bolts connecting tray sides to risers were not 'close tolerance', and often rejected my 'proper' 10mm AF spanners & drivers. The wider 'Metrinch' tolerance sufficed. And, usually, cleared enough flash / burr from nuts and bolt-heads for the 10mm tools to then grab and tighten.

( A 10mm nut-driver in budget 3.6 V cordless screw-driver saved me almost an hour per trolley... )

 

[MidgetDwarf]

Merica!!!!!

 

[Baluncore]

Merica!!!!!

I hale from the anagram, Mercia.

 

[chrisbroward]

Bumping this because I found some new info!

Apparently (digging through other forums, and looking at old textbooks from archive.org) -- there actually used to be TWO systems of English units taught in the United States, and Great Britian.

One system used pound as a the force unit (Avoirdupois), and slug was the corresponding unit of mass. One pound-force will accelerate 1 slug to 1 ft/sec^2. On earth, 1 slug will weigh 32.2 lb (Avoirdupois).

System two used the pound as a unit of mass, the corresponding unit of force was the POUNDAL. One poundal will accelerate 1 pound-mass to 1 ft/sec^2. One poundal is the equivalent of 1/32.2 lb (Avoirdupois) or 32.2 pound-mass will weigh 1 lb (Avoirdupois).

 

[gmax137]

Engineering textbooks (US 1960s and 70s) explained all this in the first two pages. It really isn't complicated.
Do you know about kips yet, lol.

 

[sophiecentaur]

This thread should be filed under 'History and Politics'. There's a high proportion of opinions and 'instances' and very little Science.
The reasons for having a range of units in any system is convenience and usage. There's a lot of inertia in the choice and use of terms in Engineering because of the way it has been taught - many vocational courses can present a topic in a very insular way ( no time to go in depth) and the same can be true about apprentisships (loose specifications of course content which can be delivered by non- academic staff). These factors lead to the survival of a loose approach to units.
I don't know the solution to this problem as the alternative costs more money.

 

[gmax137]

I don't know the solution to this problem as the alternative costs more money.

I don't think having several sets of units is a problem. As long as each is well defined and useful to those using it.

If (when) someone makes a mistake in their units, it is because they aren't being careful. It is not the unit's fault.

 

[sophiecentaur]

I don't think having several sets of units is a problem.

It's potentially a massive problem for communication between even clever peoplr. If you never have a problem then you are lucky or very smart.

 

[Ranger Mike]

Metrology is the Science of Measurement
Measurement is the language of Science
Measurement is a Universal Language