Re: ATM A cage as secondary holder

[iss@pvtnetworks.net]

Mel wrote,

>...that's right, if the OTA rotates around the OA, such that as the scope moves
>from horizon to zenith, it will rotate 90 degrees around...  so it starts by
>needing a horizon correction and ends with needing an elevation correction...
>definitely something that's better fixed mechanically than in software, don't
>you think?

Good description, I hadn't visualized it quite like that...:)

Now, how do we get the elev trunnions (usually ~180 deg sectors)
concentric after they're mounted on the OTA? It seems that once
you do this you shouldn't move one of them later to square the
OA with elev.

I built a 13" a while back that had a open ended box with the trunnions
on 2 sides. The OTA was slid into the box for assembly and the entire
OTA could be shimmed (tilted) relative to the box to get the OA 
square with the elev axis. The idea was to have a quick change mount
that could accept more than 1 telescope or camera, the OA alinement
was a fallout.

Andy Saulietis / ISS Alt-Az-Fp Drive Systems
HDPE Worm Gears, Custom designs & Machine work
29 Serenity St  Mayhill NM 88339
505-687-3067 Voice
505-687-3021   Fax
e-mail: iss@pvtnetworks.net
32 54 13 N  105 31 44 W 7300' elev

"The journey of a thousand miles begins with a
broken fan belt and a leaky tire."