Rotating Ballnut - design ideas

[magicniner]

Hello magicniner, forgive my limited intelect, but what is the difference between "whipping in the ball screws and not rotational mass"? what solutions are you referring to? Thanks for the info. Mutzy

The difference between 1-"whipping in ballscrews" and 2-"Rotational mass is that

1. "Whipping" is when the length allows sag and rotation then "Whips it around" like a skipping rope resulting in a lot of off-centre mass and the associated vibration and potential damage.
and
2. "Rotational Mass" refers in this case simply to the mass which requires acceleration and deceleration to control a rotating screw assembly.

One of the simplest solutions I've seen is like a sprung saloon swing door with a slot in it, the slot fits the ballscrew and supports it in 3 directions, when the carriage passes it "pushes the door open" and the door swings back once it passes, a few of these spaced out along the screw on alternate sides will control whipping very effectively.

There are other more complex solutions but they can approach the cost of a rotating mount for a ball nut and as stated address only whipping and not rotational mass,

Regards,

Nick