Help with imperial measurements

[daedalusminos]

Yep half of 75 and 5/16" is 37.5" and 5/32

I prefer to normalise first....
75" = 1200/16ths + 5/16ths = 1205/16ths

Half of = 1205/32nds

 

[daedalusminos]

Not the case at all. I NEVER set out to offend anyone, my comments were meant as always, in a humourous way.

Just use the smilies, readers then know how to interpret your replies. I took a pop @mtt.tr but used a smiley and he understood it was in jest.

 

[My Old Landy]

I prefer to normalise first....
75" = 1200/16ths + 5/16ths = 1205/16ths

Half of = 1205/32nds

You see, it is simple once you understand
The Imperial measurement was one of our finest exports. I use both due to my age and upbringing but as both of my lathes are Imperial, I have mostly Imperial gear. I do love these threads, they make me smile every time

 

[bricol]

Easywelder: It’s only fairly recent that one can actually purchase a metric/ imperial tape measure - and they are few and far between!

I think of all the tapes I own, only one is metric only, so I'm surprised at that - we used to give away combined units ones with our name on 20yrs ago.

 

[bricol]

One of my big long standing clients is European and a few years back they opened a facility in the usa.

The USA site is big and filled with our machinery but Americans being Americans, they decided they knew best and started modifying some bits of kit to "work better" despite it being already very efficient.

Needless to say, within short order they started to complain that things weren't working properly so I had them send some bits over for me to check.

I had a call with them and told them I'd found the tolerances on the modified kit were awful. "Oh, it's fine" says one of their engineers, "We added an inch to it".

The client sent on of their European engineers over to the USA to have a look and he took loads of pictures and videos of the equipment and how they use it. To say it was a bit slapdash and shonky would be very kind indeed!

But that's really just a person thing, not an American thing.

I have been confused in the past that stuff I designed seemed to not quite work as I intended - then I discover the machine shop lads had added a bit onto carefully toleranced components, as "they knew where it fitted" and wanted to make sure it did . . . or fabricators adding a bit for the same reason . . . or just casually drilling holes a smaller size and using smaller bolts as they thought the ones I had specified were over the top . . .

 

[Richiew]

If I'm making something and I have a choice, then I often use inches as the lines are bigger on the tape measure.

 

[bricol]

All of that is true, but it doesn't make it a good thing. If America ever sees the light and migrates to metric (which is unlikely I know), imperial will die pretty quickly I think. I can use imperial units, I just choose not to most of the time because I haven't found many redeeming features. I've seen too many problems caused by engineering drawings mixing up fractional inches, decimal inches and drill numbers/letters (where the metric system would just use millimetres without any possibility of confusion).

Oh and of course, "most of us know what a pint or gallon means", but if you talk to an American they'll say (assuming they're enlightened enough to know some metric) that a pint is 473 ml whereas you or I would say it's 568 ml.

I've seen millimetre drawings that cause confusion - international drawing standards, and even the American standard is international, state inch drawings use a ".", but metric drawings use a "," for decimals.

So what do we do on our companty drawqings . . . use millimetres and the "." So if you don't see the whole thing, and the bit that states "millimetres", you could be forgiven for assuming inches . . .

The difference in volume of our imperial gallon and the American gallon is how I tell American owners of Dodge Challengers to increase mpg - do what I did, swap the settings buried in one of the menus to UK gallons - instant increase in displayed mpg

 

[Dr.Al]

If someone asked me what a unit is in inches†, I'd give them an accurate answer, but use my own preferred denominator.

For example, if my measurement is 14 mm and they wanted it in inches, I'd tell them it's 140/254". I think two-hundred and fifty-fourths of an inch should be a much more common imperial unit that we should all promote at every opportunity.

 

[Dr.Al]

I've seen millimetre drawings that cause confusion - international drawing standards, and even the American standard is international, state inch drawings use a ".", but metric drawings use a "," for decimals.

So what do we do on our companty drawqings . . . use millimetres and the "." So if you don't see the whole thing, and the bit that states "millimetres", you could be forgiven for assuming inches . . .

I don't really understand the problem there. Whether it's imperial or metric is completely separate to whether it uses a European decimal (comma) or UK/English decimal (point). Just because a lot of metric drawings use European standards and hence use a comma and a lot of American rubbish uses a decimal point, doesn't mean you can't have a decimal point and metric units.

I've seen plenty of metric drawings with decimal points instead of commas; it would never occur to me to assume imperial on the basis of something like that.

If you saw a drawing dated "May 6, 2022", would you assume it was imperial just because it had an American format of date?

 

[daedalusminos]

For example, if my measurement is 14 mm and they wanted it in inches, I'd tell them it's 140/254". I think two-hundred and fifty-fourths of an inch should be a much more common imperial unit that we should all promote at every opportunity.

But why not express as 127ths....peeps will then understand that when their lathe is missing that 127T change gear they can't cut metric threads....unless it's Colchester or Harrison and round to 63T!

 

[Parm]

I can but it's never by choice.


Who would rather workout half of 75' 5/16th or 1913mm

No brainer

Metric all the way for me

 

[Parm]

Before I retired from Aerospace as a Measurement Engineer, we often used to quote coulombs per cubic fortnight to baffle management idiots

Just explaining something simple often causes enough bafflement

 

[brightspark]

if you were a model maker all the drawings are in imperial so you wouldnt have a clue unless you converted all the measurements

 

[Agroshield]

I've seen millimetre drawings that cause confusion - international drawing standards, and even the American standard is international, state inch drawings use a ".", but metric drawings use a "," for decimals.

The two main dimensioning standards are ISO129-1 (easier to find a pdf version by looking for BS EN ISO129-1) and ASME Y14.5 (also available as a pdf).

Section 4.1.1 of BS EN ISO129-1 says "Dimensional values indicated in decimal notation, shall use a comma as the decimal marker." I was shocked when I saw that - the British Standard for dimensioning makes mandatory something that we do not use here.

ISO129 does not acknowledge imperial at all. The ASME standard provides for both sets of units, and gives a rule for expressing an imperial measurement on a metric drawing, but it has a standard decimal point (full stop) for both units (sections 4.3.1 and 4.3.2).

 

[Kayos]

1/2" nominal bore of sch40 pipe.

Pretty easy to get used to for all the sizes, and with only a little experience, easy to recognise what is what.

I can identify the size of pipe from 2 metres away, it's the fact that the pipes bear no resemblance to the measurements

 

[caprinut]

As an engineering machinist using imperial units is a complete pain, you might not think I'm actually old school. NASA lost a cool 125 million with the Mars Climate Orbiter they screwed up their metric/imperial conversion and it crashed into the Mars atmosphere. At least two airliners have been lost for the same reason lbs to kgs of fuel the fuel tanker pumps in liters so you have allow for the specific gravity of Kerosene aswell. At least BSP threads are almost universal except in the good ole US of A.

Bert

 

[zzr1200]

Some more English measurements.
My garage/workshop is about 2 perch....

Measurements - The University of Nottingham

 

[eLuSiVeMiTe]

Inches are good for day to day, normal-person measurements, maybe even better than metric, because they're just the right size for a single digit to describe, with reasonable accuracy, most things you encounter in a day. Lots of things the average person handles, or would need to know the size of, are in the range of 1-10 inches, millimetres are too small and meters are too big for single digits to be useful, this is why children are taught centimetres, because the size of most things, in centimetres (and in inches) is easy to comprehend. I'm sure there's a word for it but I can't think of it right now, not "tangible" but something like that.

For example, "Three inches" is 3 syllables so it's easy to say, and accurately describes something as between 2.5" and 3.5", which is enough precision for "Will this vase fit on that shelf?. You can hold a tape somewhere near an object and call out its size in inches, using millimetres you have to be more careful because they're so small, too small for them to matter to most people. In metric you'd say "Seventy five millimetres", that's eight syllables and technically means between 74.5 and 75.5mm, so it would be more accurate to say "About seventy five millimetres" and if anything it's more ambiguous as no one knows what rounding interval you've used (But would probably assume 25mm so you're basically using inches by a different name).

Of course if precision does matter, that argument goes out the window and it doesn't make a lot of difference what you use as long as you're comfortable with it. I machine in decimal inches because that's what my leadscrews are, I could produce the exact same parts on a metric lathe just as easily.

For anything more technical than simple lengths, using imperial units is a massive pain, especially if electricity is involved as there are no imperial units.

Dunno. I usually say about 60mm about 200mm then move on to 1.2 m and so on.

 

[eLuSiVeMiTe]

Not the case at all. The whole point of real measurements is that they are/were directly related to a real object. It is easy to visualise someone who is 6'6" and 15 Stone, but utterly meaningless if they are 2.3m and 150Kg. Both systems have their uses, it is a shame that the educational system in this country has dumbed down so that people know so little about the world around them.

Speak for yourself. 100mm less that a 2x4 @2400 (stud wall size or standard ceiling height) and 6 bags of cement. ( 3 of old)
And yes. I called it a 2x4.

47x94 if you want to be picky.


Oh and 2300mm is over 7 and a half feet.



1982mm metric height of a standard door

 

[DAPPH]

I t'wer brought up to use cubits , thumbs & other body parts ..... me pyramids are still standing . Some days what was six inches often became three so you can imagine the skills I needed to get the pyramids built .

Ancient Egyptian units of measurement - Wikipedia

en.wikipedia.org