Text & Border Sizes X4

Hi, new to the forum and would appreciate your help.

I've started designing signs for a sign carver using inches instead of pixels or points. I did an oval today on a 24' x 36" layout for a D size plot or print.
I made the border 1 inch wide and the letters 4 inches.

The oval is 28 inches long and 18 inches wide. When I did a test plot the oval was 27 inches long and 17 inches wide with a 1/2" border.
The letters were 3 inches instead of four inches.

I saved the file, or exported it as a pdf file.


What am I doing wrong and how do I correct it?

Thanks in advance for your help.

Anuta