Tested a 24″ x 36″ base using 1/4-20 for the long x-axis. Quite a bit of flex at 36″, was limited to ~40 IPM before stepper stutter locked it up. Added a clothes pin and some duct tape to dampen step vibrations – got to ~80 IPM. Borrowed a piece of 1/2-13 to try – much smoother. The extra mass helps dampen the noise and the inertia evens out the pulsing. The rod is bowed so it still vibrated at higher speeds.