Modern GEM manufacturers have forgotten the old guideline to prevent flexure. I can't remember if it was Ingalls or Porter, but to paraphrase, "the mass relationship of a telescope to it's mount should be the same as that of the hands of a watch to it's works". Just look at the differences between the Astrola and Star-Liner GEMS of 40 years ago intended for 10" class scopes, and modern GEMS. Mass has been sacrificed wholesale on the altar of portability. (Does Parks still sell those old-style, beefy mounts?) Three cheers for Bruce and his pipe-fitting mounts. He's never forgotten the mass relationship guideline. For any cantilvered mount, it's a must. Otherwise, alt-az mounts with practically vertical load-bearing paths are the only alternative- and then you have to deal with field rotation. Kurt, the acid test is to try the mount with a much smaller scope. If the problem is gone, then Don's hit it on the head. On 7/31/07, Kurt Fisher <fisherka@csolutions.net> wrote:
Chuck and Don,
It seems I'm trying to get more out of the mount than can be achieved. Looks like the best I can do is add the extra heavy-duty mounting bar that I've ordered, do an extra check for any loosness in the OTA and then hope for the best. But I'm still not sure I'm following the cone error reduction instructions properly. (Silly me, looking at the advertising literature and expecting the mount to work as advertised. And all for only $2K.)