And the problem with sand is? Filling with sand probably won't do
much for the stiffness, but would kill the vibrations. It would also
increase the mass and therefore the deflection caused by a bump.

What causes your problem? Stepper motor?

Putting the aluminum under tension will do nothing as far as I know.

Dan


domain (qedude) wrote in message ...
I'm hoping someone can help me with a problem I am having. I have a telescope
mounted on a 54 inch tall, 3/16 inch wall, 8x8 square aluminum tube with 1.25
inch plates welded to the top and bottom and bolted to 2/3 of a yard of
concrete. The problem is I am getting a little too much movement out of the
tube and I need to increase the stiffness of the tube. The ideal situation
would be to replace the tube with something larger but that's just not possible
at this point in time. I don't need a radical increase in stiffness either so I
think there is something I could do to for a slight increase in stiffness. I
need to kill low frequency vibrations so please don't suggest sand or concrete,
beside concrete and alumimun don't get along with each other. Any ideas ? Would
putting the tube under tension help ?


Scott Hogsten