When dimensioning diameters the default on most CAD systems is to put
the diameter symbol before it's measurement.
I was always taught to do the same when making notations within text.
However I have just shifted industries from Mechanical to Civil, and
joined a new company, and am being picked up upon this habit with them
saying it is incorrect.
The contention is that you don't say a diameter 14mm, you say a 14mm
My contention is that you also don't say pound 10 but you still put the
symbol first, or radius 14mm, but still put the r first.
Has anybody else come accross this?
Which is more correct?
#9 = number nine
9# = nine pounds (although we write "lb.")
r9" = radius nine inches
Autocad has a diameter symbol and it follows the numeral and inch tick
marks. (Can't show you here)
Autocad also has a degree symbol and that follows the numeral.
I comlpetely agree with you. It should be Ø14mm, and not 14mmØ, simply
because mm are units of something, like pounds, acres, litres or decibels,
and should go AFTER the number indicating the size of said unit. The
diameter symbol is NOT a unit, it indicates the type of measurement used
(Radius, Diameter, Arc, Angle, Profile, etc.) and therefore is more
meaningful when placed BEFORE the number. It is also easier to understand
with the diameter symbol first and units later rather than units and
measurement type after. At least that's how they teach it in mechanical
drafting school. Perhaps in architectural drafting school they teach it the
other way around ?
However, it is common practice in architecture and civil work to put the
diameter symbol at the end. God only knows why they do this, but it only
takes a few reads before you get used to it. I suggest you adapt to the
methods of your company, not the opposite. Unless you want to nag everyone
every time you see a 14mmØ and are ready to have customers call you saying
they screwed up an assembly because they misunderstood your dimension. It
happenned to me a few years back. Not pretty.
It is fairly well known that engineers don't like architects, and
vice-versa. It is not a Universal Truth, but ask around. Both misunderstand
and underestimate the implications of the other's work.
I'm very tempted to single handedly teach the entire architectural and
civil engineering community how to do things right.
At least I'll be able to warp my juniors to my will... I mean educate
the juniors correctly.
Thanks for the spell checking as well. I saw it, and kicked myself,
just after hitting the post message button
Dr Fleau wrote:
Most metric standards have the symbol in front of the value whereas
most imperial standards show it after. The reason for this is because
it is the convention in some countries to use a slashed zero, so
placing the diameter symbol after a value could see it being misread.
Even where it is not a convention, some users with place a slash
through a zero for clarity and so this can result in values being
The radius symbol is also before for consistency with the diameter
From the Oxford Dictionary:
(among other things)
mark or character taken as a sign of some object or idea or process,
e.g.the planet signs, chemical elements-letters, letters of the
Sorry, I could not resist :-))