Need 6' x 4' bed, 4 axis router design.. Help..!

[irving2008]

I would have thought that the hollow section, being less stiff than the solid one would start whipping at a lower speed.... like for like on external diameter. I am sure the critical speed is related to the stiffness in some way.

[Jonathan]

I am sure the critical speed is related to the stiffness in some way.

That would seem logical since tensioning the screw sort of makes it stiffer, and also raises the critical speed.