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Possibly because the width of the roll can be changed and ordered in whatever unit you like, but the diameter is fixed by the machine that makes the roll. Rolls are similar to pipes and almost all pipes are made and ordered in "inches". However this is a nominal pipe size, historically things were done in inches so the dies and formers were in inches and the engineering was in imperial AKA inches. It is nominal because that is just a start point or a convenient "name". You make a large pipe in a former, but the critical dimension is the inside diameter which is obviously the outside minus twice the pipe thickness. Since there is a variance on wall thickness and a variance in sizing control you can order a "40 inch" pipe but the actual dimensions are not 40" and are as easily measured in mm as inches. In the same way almost all pipes are ordered to a minimum maximum length of circa 12.125m this is so they fit in and on 40' trucks and containers. From this most welding set ups have the machines set 12.125m apart which is 40' minus a bitI worked in a paper mill for 22yrs, 20 of them running a Voith winder. We measured the width of the paper roll in millimeters and the diameter in inches
Freedom units v the metric system
Americans don't want our King but they love an imperial measure
Ok, I get it now. It's just how many of each unit of measure does it take to constitute the next one indicated by the line/ arrow.
Pretty simple now that I see it.
And 4 poppyseeds to the baleycorn. Of course. Everyone knows that.
Yes metric is much easier and in my opinion better in a practical sense but the twip, pica, and shaftment definitely hold the edge in entertainment value.Now tell me without using a calculator
Metric is just so easy.
- How many Palms to a Gunthers Chain, and
- How many inches to a Nautical mile
The only people who use centimetres are dressmakers, everything else is millimetres / meters.I Hate metric tape measures.
I did grafting for years in the US, inches.
Came to Oz, did draughting, metric, mm's.
But civilians talk metric in Centimeters!!!!!!! WTF.
Then when you use a tape measure, its in Centimeters / Meters.
Why can't it be in continuous measurements, like 90 then 1000, 1100, 1200???????
Instead of 90 then 1 then 10 again, gives me the shits.....
I wanted to order a piece of glass 120 x 350, he wanted hundreds for it!!!!!! WHAT????? That's a big piece of glass! What A2 size? Oh, you want millimeters!!!!!!
Then long ago I had an American engineer tell me metric was more accurate!!!!! Bwahahaha An inch is an inch, even at 25.4mm.
I can and do use both, but metric is far easier to do conversions and multiples of.I can saw you a pipe 102 millimeters and be spot on. I can saw you a pipe
at 12 feet 3 and 5/64 of an inch and be spot on. So why is it easier if you
know both methods. Because YOU don't know both? I know both and can do
both. Neither one is better than the other, it's all in what you use. It's an attitude
that I see is the problem, not the measuring system. JMHO. John
Certainly not in UK, they take a very logical system and by switching between mm/cm/ and meters they manage to screw it up, usually by a factor of ten. They do the same in F1 and athletics, speaking in decimals of a second, thousandths then giving the actual number I frequently cant understand what on earth they are talking about.The only people who use centimetres are dressmakers, everything else is millimetres / meters.
Never heard anyone else use cm...
I can saw you a pipe 102 millimeters and be spot on. I can saw you a pipe
at 12 feet 3 and 5/64 of an inch and be spot on. So why is it easier if you
know both methods. Because YOU don't know both? I know both and can do
both. Neither one is better than the other, it's all in what you use. It's an attitude
that I see is the problem, not the measuring system. JMHO. John