Hi Michael,
I've included a drawing. The rail was created at 30 inches long. I followed you instructions to change the units to millimeters, but it comes out saying that the rail is now 30mm long. I believe that is should be 762mm.
What am I doing wrong?
Thanks,
Mark

If you have a file that has no unit system, then change it to milli's, there will be no scaling happen.. It will now just be 30 mm... For the file you just posted, I made a workspace of "no system units" then "Imported" the file in.. I set the units to "Inches" which set the rail at 30 inches. Then I set the units to millimeters and the rail was scaled to the 762 mm you were looking for...

Hi Mark, it looks like the file you attached there was saved after you switched the units to mm.

Could you please post the file _before_ you switched the units to mm so I can take a look at the original file? Did your original file actually have units set to inches, or was it possibly set to "No unit system" ? Because if was set to Units = "No unit system", then it would behave like you are describing since like Burr mentions switching from "No unit system" to a different system does not apply any scaling.

So if that's what you are running into, first switch from "No unit system" to inches, and then switch from inches to mm and that should give you the scaling you want, as long as the option "Scale on unit system change" is enabled.

- Michael