[ATM] Importance of balancing mirror cell parts?

["Olivier Biot" <olivier.biot@versateladsl.be>]

Hi folks,

The recent thread on bearings in (static) mirror cells gave me much information, for which I am really grateful! A new aspect popped in some hours ago, and has to do with the balancing of the different levers and triangles in a mirror cell.

If one wants to build a mirror cell that "doesn't" add extra flexure to the mirror when it is not aimed at the zenit, then I guess that all parts must be in perfect equilibrium. For a classical 18 points cell consisting of 3 levers and 6 triangles, this means that the rotation axis of the levers goes through the lever's center of gravity (hereafter abbreviated as COG), and that the triangles are supported at their COG. Correctly balancing the triangles on the levers implies that you provide a "counterweight" to compensate for the offset of the triangle's COG with respect to the lever.

I currently envisage the following construct: the levers have an axial bearing at their COG, and have a small rod perpendicular to the lever's plane. This rod will host a triangle on one side through a bearing (like Bruce Sayre's design with a ball joint bearing), which is mounted so its 3D centre coincides with the 3D COG of the triangle. On the opposite end of the rod I'd provide a counterweight, so I compensate for the triangle's weight on the lever.

What do you think about this approach?

Best regards,

Olivier
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