Jphii,
I was just ribbing you about the pop ups. The recommendation is to have two bolts for the armboard. Both bolt threads should be in the armboard, one for pivot, one for true locking. The plinth shape would need to change at this area and the plinth would need an arched slot to accomodate the pivot. It's way to easy to bump the armboard with the one bolt doing dual purpose. This design change would also allow you to place a cone more directly under the arm tube center which would assist any vibration on its way to earth.
I was just ribbing you about the pop ups. The recommendation is to have two bolts for the armboard. Both bolt threads should be in the armboard, one for pivot, one for true locking. The plinth shape would need to change at this area and the plinth would need an arched slot to accomodate the pivot. It's way to easy to bump the armboard with the one bolt doing dual purpose. This design change would also allow you to place a cone more directly under the arm tube center which would assist any vibration on its way to earth.