I want to use a 6 mm carbon fibre rod or tube as the pendulum rod in a precision clock that I am making. The pendulum bob weight is 5 pounds.
The rod needs to be rigid, have a very low temperature coefficient of expansion, and must be dimensionally very stable.
Questions:
Is there anything to choose between rod and tube?
Is a pultruded item better than wrapped in this application?
Should I be looking for a product that uses epoxy rather than polyester resin?
Would a gel coated item be better from the point of view of water absorption?

Any advice would be greatly appreciated

Mike