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Steve,
Small mirrors of reasonable thickness ratios don't need fancy cells. Only necessary for thin mirrors. I have always collimated my scopes comfortable for my eye which is usually pointing up slightly. My 6" mirror is a 1:6 ratio. It sits on three 4mm brass screws machined down to a point on the tip.
It sits loose in its cell, that is, it can rattle when pointing horizontally. However, it is mechanically restrained so that it can't fall out but that looseness keeps the mirror free of stresses and the figure true.
So I would always point the scope up in a direction that the mirror is siting in it's observing orientation. The style of mounting cell really depends upon mirror size and thickness ratio.
I notice you haven't posted for a long time about the mirror you were making? Have you finished using my Foucault tester? Can we arrange a return at some stage?
Cheers
Joe
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