Printing with MacPaint pictures that are 576x720 (72dpi for 8 inches by 11 inches):

I couldn't figure out why printouts got clipped on the right edge of the page and finally realized that the stepper motor movement is approx 8/9 ~ 9/10 or 1.11 * 144 = 160 steps per inch. If I just scale the page a little bit wider (multiply by 1.11) then everything fits as it should.

Test that fills the 8 inch MacPaint page width:

[Linked Image from i.imgur.com]