Re: AP1100 autoguiding

Christopher Erickson

When adjusting cone error on OTA's, I often make thin shims from the sides of aluminum pop cans. They are easily cut with scissors and paper punches. And don't stack too many shims together or you might end up with a slightly compressible spacer that will introduce some additional flexure.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738

On Thu, May 19, 2022, 8:06 AM Steven Panish <scpanish1@...> wrote:
Chris's points are good.  I'm hoping the RC arriving shortly will be stable. 

On Wed, May 18, 2022 at 1:32 PM Christopher Erickson <christopher.k.erickson@...> wrote:
Dovetail bars and radius blocks or rings are just about always quite a ways farther apart than the ends of dovetail brackets and hence a better place to attempt fine adjustments of cone error. Further, the actual error is almost always in the OTA and its support structure, not the mount and dovetail bracket. Routinely swapping OTA's on the same mount (as I often do) would be a real problem.

And make sure that OTA is precisely collimated before attempting any cone error adjustments.

And a compound OTA with a floating primary might have a lot of variability in its cone error as it points around the sky and shifts the primary mirror's orientation to gravity.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738

On Wed, May 18, 2022, 5:06 AM Andrew J <andjones132@...> wrote:
On Sun, May 15, 2022 at 02:40 PM, Steven Panish wrote:
Unfortunately it is rare  to find cone adjustment screws actually on plates or rings. 
@steven Panish. You make a good point. I wish the saddle plates came with adjustment screws to be able to correct for cone error. It would be so easy to adjust if there where screws that would allow you to adjsut the angle of the dovetail plate in the saddle. Shims are OK, but it woudl be much easier if this was built into the saddle plate. Just my 2 cents....

Andrew J

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