Quote Originally Posted by JAZZCNC View Post
torque produced by steppers and ballscrews can twist and mangle a gantry built like this in the blink of an eye when the stick stuff it's the fan. :surprised:
Yep, mine has done that once or twice. It's quite surprising. Once nice test I can do is if I disengage the motors and rotate one ballnut by hand the gantry is stiff enough to make the other one backdrive and rotate too... but not much.

I wonder how much difference it would make if you have two ballnuts on the single screw? One on each of the two cross pieces on the gantry.