anyone have Creatbot or Mankati fullscale that I can refer?
my printer have Z woble, please take a look at the video.
how can I make sure the ballscrew nut it tighten precisely center?
is the top rod should have nothing to hold like in the video?
Thank you very much! I tried tighten it but it still have z woble 
When trying to solve Z-wobble, you want to constraints the bottom of the rod, not the top, relative to the stepper motor. So if your stepper is mounted upside down, you’ll want to constrain the end closest to the stepper.
@_Spice Agreed. Also it seems like your main issue here is that the ball nut is improperly secured to the bed, try using larger screws to give it less play.
@_Spice @Adam_Steinmark how do I tighten the ballscrew nut precisely centered?
If you use thicker screws to attach the nut it should self-align. The free end of the screw isn’t a big issue because the linear rods help constrain the movement. Your main issue is how much play the ball nut has with the mounting.