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[Closed] Why cm

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I was looking at the post about removing the fireplace and not wanting the house to fall down and when I see centimetres mentioned I immediately think blue peter or schoolteachers definitely not building trade experience.
It's either millimetres or metres and no confusion and you may have guessed Im in the trade
So have centimetres got any use anywhere


 
Posted : 03/01/2017 5:16 pm
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It's a bigger sounding number than using inches. If you need that.


 
Posted : 03/01/2017 5:18 pm
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It's what's taught in school innit.
I learned in CM, but as a woodworker, I use MM....and CM.....and inches.....and feet.... and fathoms... whatever people say to me I have to convert.
Mostly MM makes sense I think.
Feet and inches can bugger off...

It's a bigger sounding number than using inches. If you need that.

True, people don't seem to like to say seven hundred and fifty millimetres, and would rather say seventy five centimetres... It's ok, but it'll generally tell you that they are not in the trade.


 
Posted : 03/01/2017 5:19 pm
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try decimal feet..


 
Posted : 03/01/2017 5:20 pm
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Real Estate is such a backward industry, much of it is still quoted in square feet and acres.

10.7639 is a number I have to use v often 😉


 
Posted : 03/01/2017 5:21 pm
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[i]try decimal feet.. [/i]

It's only people in Norfolk that still have to use base 12 when using their feet...


 
Posted : 03/01/2017 5:21 pm
 IHN
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Surely if they say 'millimetres' and not 'mil', they're obviously not in the trade?


 
Posted : 03/01/2017 5:21 pm
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When you buy timber, very often it's bought in Imperial, because it's imported from the States etc, but when you start cutting it up it's in MM...
Crazy world...


 
Posted : 03/01/2017 5:22 pm
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I used millimetres to get the point across but definitely 750 mil never 75 whatevers, as for imperial I did get both at school but it's a useless measure too although I like miles and 32" for jeans


 
Posted : 03/01/2017 5:27 pm
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Inches really screwed my head when doing my apprenticeship was told by the tradesman to cut stuff in inches "cut it 6 3/8" loon " WTF is that in mm? 😕


 
Posted : 03/01/2017 5:28 pm
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At work we don't even use metres half the time as a lot of what we do is measured to the mm.


 
Posted : 03/01/2017 5:28 pm
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10.7639 is a number I have to use v often

Or 0.929


 
Posted : 03/01/2017 5:31 pm
 aP
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For some reason when we (ie the UK) adopted the Metric system in the early 70s, someone thought it better to measure buildings in millimetres. So, as a consequence, everything I do is designed in millimetres. Except for all the rail and transport infrastructure stuff I do which is in metres.
In mainland Europe, however, they use centimetres. This causes endless amusement in my office as I ask them how big something is and they say 60, and I have to say "is that 600?, or sometime 60,000?) Seeing as they also use metres.
My assumption is that using millimetres means never using a decimal point, as buildings aren't able to be built to tolerances that would require the use of half millimetres.


 
Posted : 03/01/2017 5:33 pm
 Nico
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Sixteenths of an inch are the way forward.


 
Posted : 03/01/2017 5:34 pm
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Too early to mention Brexit in this thread?


 
Posted : 03/01/2017 5:36 pm
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When you buy timber, very often it's bought in Imperial, because it's imported from the States etc, but when you start cutting it up it's in MM...
Crazy world...
A bit like MTB & road bike sizing. One usually imperial, the other usually metric....

Confuses the hell out of me.


 
Posted : 03/01/2017 5:36 pm
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My assumption is that using millimetres means never using a decimal point

Yes. Imagine what consequences a decimal point in the wrong place could have.


 
Posted : 03/01/2017 5:38 pm
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So have centimetres got any use anywhere

Them europeans seem use them all the time. Foreigners aside if people give me measurements in CMs - especially in suspiciously whole numbers- its usually a good sign that they've not really given too much attention to taking the measurements. I find if people take measurements for things that needs to fit in MM and if they estimate sizes of things where proportions and scale matter in ft and inches then they can usually be trusted.

"453mm" Trusted
"45cm" [i]NOT TRUSTED[/i]
"about 12ft tall" Trusted
"about 4inches" Trusted

Centimeters seem to be the preserve of people who don't really know what they are asking for, or don't really know how to ask for it


 
Posted : 03/01/2017 5:38 pm
 aP
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Centimeters seem to be the preserve of people who don't really know what they are asking for, or don't really know how to ask for it

Ouch, but I like that 😉


 
Posted : 03/01/2017 5:43 pm
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I tend to think of my metric height in cm rather than mm or m.


 
Posted : 03/01/2017 5:45 pm
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Ouch, but I like that

Kinky

Surely if they say 'millimetres' and not 'mil', they're obviously not in the trade?

Depends on the trade - you can expect someone who [i]says[/i] "Mil" to mean millimetres. But if they write it as 'Mil' they might actually mean a thousandth of an inch.

Sixteenths of an inch are the way forward.

Presumably you're embarking on a pretty short journey.
"are we there yet?"
"just a few barleycorns to go"


 
Posted : 03/01/2017 5:47 pm
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Usage seems to be metres as the base then up or down by three orders of magnitude so nanometres (10 ^-9), micrometres (10^-6), millimetres (10^-3), metres(10^0) and Kilometres(10^3)


 
Posted : 03/01/2017 5:51 pm
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When you buy timber, very often it's bought in Imperial, because it's imported from the States etc,.

Annoyingly sheets are in imperial but lengths of timber - certainly with building timber - its in the nearest metric equivalent to imperial -so a '16ft' length is actually 4.8m and about 3 inches short of a full 16ft. So if you're framing for something that going to be clad in 8x4 sheets the lengths are too short to cut and divid efficiently. I have to frame up dozens and dozens of 8x4 sheets making film flattage and you have to be careful not to get left with lots of nearly-long-enough scrap

but when you start cutting it up it's in MM

I only buy fully metric tape measures as I get annoyed working in tight spaces when you can only work from one side of the tape. You quickly get used to counting in Base 610 though


 
Posted : 03/01/2017 5:57 pm
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It's what's taught in school innit.

No not really. Science uses m,mm, micro metres and nm. 1000 each time. cm are pointless and annoying. I guess they are used because people could compare them easily to inches and its stuck.


 
Posted : 03/01/2017 5:58 pm
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But if they write it as 'Mil' they might actually mean a thousandth of an inch.
Thou surely? In the classic car world I've mostly (always?) seen it written and Thou (and said accordingly)


 
Posted : 03/01/2017 5:59 pm
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Thou surely?

Americans call 'Thous' "Mils" for some unfathomable* reason

I'm unsure what the nearest metric equivalent is for an "unfathom" is though


 
Posted : 03/01/2017 6:03 pm
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It's what's taught in school innit.

No not really. Science uses m,mm, micro metres and nm

Whoa there - You're running before you can walk - by "school" I think we're referring to primary school.

If someone gives you measurements in CM its because they've not had rummage through the draw for the 6" wooden ruler they used to have in their furry pencil case along with a compass they only every stabbed people with and a collection of smelly rubber that now all smell the same.


 
Posted : 03/01/2017 6:07 pm
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I use a horrible mix of measurements, depending on what I'm measuring.

mile -> metre -> inch -> mm -> bawhair


 
Posted : 03/01/2017 6:21 pm
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Bring back imperial measures - can't imagine that the death star's dimensions were expressed in millimetrics.
Links, chains, rods, poles and perches in the post-brexit world.


 
Posted : 03/01/2017 6:24 pm
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I hate when people mix measurements as that gets v. confusing, eg: 6 inches + 3mm when cutting something. Yards also add another element of WTF.


 
Posted : 03/01/2017 6:25 pm
 joat
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It's normally the closest integer on the tape measure, generally diy though.


 
Posted : 03/01/2017 6:29 pm
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I hate when people mix measurements as that gets v. confusing, eg: 6 inches + 3mm when cutting something. Yards also add another element of WTF.

My brother used to work with a joiner who did that.

My bugbear is people who incorrectly use uppercase for prefixes. MM isn't mm.


 
Posted : 03/01/2017 6:33 pm
 km79
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Only dressmakers use cm according to my old teacher.


 
Posted : 03/01/2017 6:37 pm
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It's all microns and nanometers in my trade 🙂


 
Posted : 03/01/2017 6:39 pm
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My bugbear is people who incorrectly use uppercase for prefixes. MM isn't mm.
What grinds my gears is thickos who don't know what a prefix is 😉


 
Posted : 03/01/2017 7:00 pm
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I work for an American engineering company, so its's a mix of mm, microns, inches and 'thou.

That continues right through to all other units - pressure, temp, power, energy - you name it and we've a right old mix.

Not a single cm to be seen though.


 
Posted : 03/01/2017 7:09 pm
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As a site carpenter whether I use imperial or metric usually depends on which way round I'm holding the tape measure, ie, if I'm measuring from the right-hand side of the tape it comes out as imperial, but if I'm measuring from the left-hand side of the tape comes out metric.

As a consequence I often mix imperial and metric dimensions for the same item.

Personally I generally prefer imperial as I find the numbers much easier to remember.

Of course with imperial measurements I'm including the indispensable "gnat's bollock", e.g. thirteen and three-quarters plus a gnat's bollock.

There's no such thing as a gnat's bollock with metric.


 
Posted : 03/01/2017 7:13 pm
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I work with a lot of Americans, use a lot of wires, rope and chain.

They still use Imperial, which means the sizes relate to the circumference. Not a very intuitive system. Especially if you want to convert to metric which references the diameter.


 
Posted : 03/01/2017 8:13 pm
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Most peeps seem happy with the cm when talking about car engine size - where 1000 cm³ (or cc) = 1 litre.
I'm an engineer and I find the cm abhorrent for linear measurements

What I hate most is the continental preference to express torque in daNm instead of plain Nm.


 
Posted : 03/01/2017 8:31 pm
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Depends on the trade - you can expect someone who says "Mil" to mean millimetres. But if they write it as 'Mil' they might actually mean a thousandth of an inch.

This does my nut in. We work in mm and microns, but a lot of our CAD tools (an materials) are from the USA with mil (what I would call thou) as the default setting. So we say mil and that's fine for mm but when the merkins say mil they mean thou and we all get in a tizzy.


 
Posted : 03/01/2017 8:32 pm
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I was taught in the mid-90s not to use cm.

I use mm generally, it keeps things simple at work and annoys the wife at home.


 
Posted : 03/01/2017 9:05 pm
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mils are milliradians, so a unit of angles, just to confuse things a bit more.


 
Posted : 03/01/2017 9:09 pm
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I build buildings entirely in mm.

My bike has 150mm forks and a 5" rear shock 🙄


 
Posted : 03/01/2017 9:12 pm
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When you buy timber, very often it's bought in Imperial, because it's imported from the States etc,.

Standard timber sizes are based on un-machined size in imperial units - doesn't have to be imported.

Annoyingly sheets are in imperial

Not always (quite unusual around here) - A few years ago I put up framing for a stud wall based on 8' x 4' sheets and ordered the same from the BM. Fixed the first sheet and thought my first stud was a bit out. Went to fix the second sheet and it missed the stud completely - the sheets were 2400 x 1200mm, not 8' x 4'. BM's response: "Yes, they're metric eight by fours".

We also get the 'Mil' = 0.001" and "Mil" = mm confusion with 'murricans. They often use both senses in the same conversation.

Centimetres are for dressmakers only 😉


 
Posted : 03/01/2017 9:14 pm
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I've seen volumes quoted in dm^3 which is an even weirder unit save that it is 1L so keeps the nomenclature of the units in check. I've yet to understand why in some applications at work we measure things in McP (megacenti-Poise).

cm works in plenty of applications. Accuracy to mm not needed/possible and values of less than 1m being and example.


 
Posted : 03/01/2017 9:15 pm
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