Okay, so I checked the Taz4 this morning. The printer is set to 100.5 steps per mm in the X and Y axis. The stepper motors are 200 steps per turn making motion 1.99 mm per stepper motor turn. At an error of 5% the machine could be commanded +/- .0995 mm. .0995 mm on the Taz4 is a little better than +/- .1136 mm on the Solidoodle. Maybe we have something now. Anybody out there have a machine that is rated to .05 mm or .2 mm?