Thank you for the input. I have not watched them make the change on their machine, and Vectorworks is not used by anyone other than me at the school that I know of, this is a faculty resource center at the community college and they usually use the plotter for poster printing for different clubs. Before I came the previous designer just drew up plans on paper not to scale, but with dimensions for people to use. I have not pulled the PDF back into VW, that's a great idea, I'll do that to see if I'm the problem somehow.
I have been checking the scale with a scale rule on the printout and used a couple of different ones In case my arch ruler is bad. I am using the Student Edition of VW but I don't think that is supposed to have any problem like this.