So Gecko's site gives the following calculation for determining push:
In. oz. * TPI * π / 8 = lbs of push
According to this if I have a 380 oz-in stepper, driving a 10 tpi screw, I should achieve 1491.5 lbs of push (of course losses will result in a lower real world situation)
380 x 10 x π / 8 (or 0.3925) = 1491.5 lbs
Is this right? If so, I think I have been over buying steppers!