AutoCAD drawing units and x,y,z scale

Mark or Chris:

How do I tell what the x, y, z scaling factors are on my AutoCAD drawing? I need to know if the scailing factor is 1 meter per drawing unit for RMS and I don't know what a drawing unit represents.

Thanks!

Tamara Butler Johndrow, P.E.

Dear Tamara :

Note that AutoCAD does not use feet or meters in model space, just its generic distance measurement called a "unit". As a civil engineer you would think of one unit as a foot (or meter). However, AutoCAD doesn't care what the units are assigned to and doesn't understand inches, millimeters, feet, or meters until it comes time to plot and you have to assign a ratio/scale to the plot. It is in plotting you assign the ratio of plotted feet or meters to a drawing unit.

Civil engineers (and surveyors) measure everything in decimals of a foot (i.e., tenths, hundredths, or thousandths) or decimals of a meter. They do not work in inches. If you specify UNITS at the AutoCAD command prompt, AutoCAD will display a dialog box allowing you to specify the units to use. For civil engineering work, use "Decimal" as your units setting. Setting the units to "Engineering" does not work. This is meant for mechanical engineering, and works in inches and AutoCAD's "units" are translated as inches not feet.

Sincerely,

Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com