Rotating Ballnut - design ideas

[Jonathan]

If I was to spin the screw the unsupported length would be 1800mm and overall length about 1900mm, so the calculations below are based on that.

J = m*pitch^2/(2*pi)^2

J = 45*0.01^2/4/pi^2 = 0.114 g-m^2

For the screw:

J = 0.5*m*r^2
Steel --> 7850Kg/m^3
Therefore:
J = 0.5*7.85*pi*r^4*l

So for mine:
J = 0.5*7.85*pi*0.0125^4*1.9 = 0.572 g-m^2

That makes the moment of inertia of the screw 5 times that of the gantry.

I will estimate J for the ballnut assembly.