Hi,
V5 I could select 0.5 to get a slightly more visible line, or 0.8 to get a medium visible line, good for showing someone a drawing. or 1.0 for about 1mm thick on screen.
I just did so in V8 and its HUGE for 0.5
choose hairline and its no thicker than default.
so the subtle line weights I chose from the list are gone.
Yep, three versions have gone by since V5… Linetypes were completely overhauled for V8. You may want to read the Help topics to get some of the differences/new functionality.
You have a print width set to 1mm. In the PrintDisplay command there is an option called Scale which is set to 1 in your case. That means a 1mm thick curve will draw as 1mm thick in your model. This is appropriate for a 1:1 print. Changing this scale option in the command will change the width.