there's been a bit of discussion on cell design lately, so i thought i'd just mention something from A SKY&TEL about a year ago...
a gentleman (forgot his name) did some research on flotation cells, and how the number of support points affect mirror figure. He used finite element analisys to mathematicly compute the difference between say a three-point support and a nine-point support. If memory serves me (it often doesn't) it didn't make that much difference for smaller mirrors - 6" or 8" - but it did have remarkable effects on larger mirrors (12", 18", ++). I don't remeber exact numbers, but I think that the typical 17.5" mounted coulter-style on three points measured in with about 1/4 wave and the same mirror on a nine-point came in more like 1/16 wave. If i remeber correctly, one suggestion that sounded easy was to cut three equilateral triangles, make support points at the tips, and then place the triangles centerd over the the three old support points.
I've been entertaining this idea for a while, for my 17.5" coulter. Has anybody out there tried this? Are there any other suggestions for making the coulter cell more friendly and robust? (especially robust; I usually drive over an hour to get to a decent starwatching site and the colliimation just doesn't improve with the drive; also there's that annoying worry-creating quiet "thump" of the mirror wiggling in that flimsy mount!!)
Thanks much from a future-atm and current light bucketteer,
mike
------------------------------------------------------------------------------ Mike Deliman <> miked@wrs.com <> phone: 510-748-4100 <> facs: 510-814-2164 Wind River Systems, 1010 Atlantic Ave, Alameda CA 94501 USA;http://www.wrs.com ------------------------------------------------------------------------------ The network link belongs to WRS... but the opinions and typos are all mine!