Please confirm drawings in cm and inches

[Doug Broad]

>1) when you say ACAD in SI what do you mean?
System Internationale
Autodesk refers to it as ISO (International Standards Organization)
(length standard = meter, mass standard = gram, time standard = seconds, .....)

>2) when you state that survayers may put 1 unit = 1 ft, where do they define that in autocad? and does that affect >the unit
of measure I would get in autolisp?

No where except in their minds. They think 1 foot = 1 unit and it is.
Plotting is easy: Whereas if 1 unit = 1 foot, 1"=20'-0" becomes 1:240 but if
1 unit is 1 foot then 1"=20.0' becomes 1:20.
>3) Im I safe to *assume* millimeters in metric and inches in english everytime?
I commonly use English system. You will need to hear from some European
or industrial users to get that answer. AutoCAD's ISO linetypes are 25.4 times
bigger than the english form linetypes. I guess its possible for some to be using
meters but with millimeters, you don't need fractions (usually).

Glad to help

[Joe Burke]

> but with millimeters, you don't need fractions (usually).

Right, Doug which brings up another point to keep in mind. Architectural
type drawings originally drawn in millimeters typically use integers (whole
numbers) only. Scaling an Imperial unit drawing up by 25.4 (inches to mm)
means you'll end up with real numbers where integers would be expected. I
think the conversion should be noted if the drawing is passed back to
someone using metric. Likewise, dimension settings should only show
integers.

I believe there are a few countries where centimeters is the standard rather
than millimeters for architectural type work. I've seen drawings from the
Philippines which use centimeters. Everything I've received from Europe,
Australia and Japan used millimeters.

Joe Burke

[Doug Broad]

Thanks Joe,
Some of that could be handled by DIMRND, by DIMDEC, and/or DIMADEC. Technically
all point coordinate values will be real values anyway although, as you say real metric
plans
usually don't have decimals in their dimensions.

There are two philosophies of conversion also (soft and hard).
Thanks for noting which countries are likely to use cm.

Regards,
Doug

[Luis Esquivel]

Not reading the post at al, but normally here in Mexico we use 0.0254 to
convert to meters and draw a foot reference line of 0.3048 to scale from
meters to english system or only me?

Regards,
Luis E.

[Doug Broad]

Hi Luis,

So you start your drawings in the English system (using 1 unit = 1 inch) and then
convert to meters?

You could start drawings in metric by using 1 unit = 1 meter (as long as your
linetype scales, dimensioning variables, and sheet sizes made sense.

If (in your metric drawings(1 unit = 1 meter), you wanted to dual dimension,
without scaling your objects) you could set DIMLFAC to (/ 12 0.3048)

[Luis Esquivel]

Hi Doug,

>
> So you start your drawings in the English system (using 1 unit = 1 inch)
and then
> convert to meters?

I have not done any drawing in Metric since 1994 only the English system,
but yes that is what I do.

>
> You could start drawings in metric by using 1 unit = 1 meter (as long as
your
> linetype scales, dimensioning variables, and sheet sizes made sense.
>
> If (in your metric drawings(1 unit = 1 meter), you wanted to dual
dimension,
> without scaling your objects) you could set DIMLFAC to (/ 12 0.3048)

Master!!! thanks for the tip.

[Scribble]

These points typically relate to architectural drawings here in Australia,
however in the civil land development field in which I work we always use 1
unit = 1metre.
We DO dimension with decimals, usually to 2 or 3 decimal places.
We "never" start a drawing assuming imperial dimensions but I always select
"English" as the convention is to use acad.pat and acad.lin with a Ltscale
of around 5 to 7.5. (probably due to historical reasons in that early
versions of acad didn't have iso versions)

HTH
cheers
Steve

"Joe Burke" <job...@hawaii.rr.com> wrote in message
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