Hi Andy

Max Smirnov's script FxGraph3D was used, with X(u,v) = (u+v)*cos(v),
Y(u,v) = (u+v)*sin(v), and z(u,v) = v.
Also minU = 0, maxU = 3,
minV = 0, and maxV = 18.85, which is just over 3 * 2 * PI, to create just over 3 circular rotations.

3D spirals were produced, but they did not expand.

Switching modes did cause MoI to hang up, in one case...

I'm too busy to look further right now. Will try again later...

- Brian

There are scripts for several spirals on the forum.

Maybe Logarithmic spiral?