Re: 1200RPA question


Hi Joe,

Thanks for that tip! I just checked, and the fork base lock screws are currently approximately at the middle of their slot holes.

Unfortunately, even if I could rotate the RA forks they are still jammed up against the RPA's adjuster block. So I'll still need to move that block a bit.

I should mention that the legs of the pier are actually not resting on marks in the ground, but on cutouts in rubber tiles I laid on the observatory floor. The north leg is now jammed as far west as it can go in that cutout, so I know the pier is rotated as far was as it can go.


---In ap-gto@..., <J.Zeglinski@...> wrote :

    I wonder if you “centered” the AP-1200  fork base lock screws to your RPA, during re-assembly.
    Maybe the screws are all jammed to one side of the rotation slot. If so, you might  “ease off” those 4 screws, and twist the mount (sliding its base around the RPA surface),  until they are in the center of their slot holes. Or, if that’s not enough, rotate the fork base until the AP-1200 fork lockdown screws are against the opposite side of their slots.
Perhaps your original setup was with the lock screws at the end of the slot to begin with, and now re-centered, the tripod foot positions no longer work as before.
Then DO NOT FORGET to lock down the fork again.
    Best done with a couple of friends to help provide some assurance, stability, and shoulder the assembled mount and scope,  maybe add some muscle to jog the base around the few degrees you need to bring back your original  RPA adjustment range. You may want to also confirm ... that your tripod legs remained on their original floor marks, during all that twisting – so you won’t confuse the original polar alignment foot positions, after your next field trip return.
    Besides, you don’t want to turn the fork, as required, only to discover that you also accidentally moved the tripod feet around in the process, and made the compensation now twice as big ... to the other side.
    You should be able to recover that lost AZ degree angle, enough to give your RPA some adjustment room again. Don’t know how “long” those slots are, but I suspect maybe a generous extra (+/-) 5 or 10 degrees ?
AP might want to confirm the fork slot rotation angle (with lock screws inserted),  for all of us here.
Hope this makes sense.
Joe Z.

Sent: Monday, October 2, 2017 1:20 PM
Subject: [ap-gto] 1200RPA question

Hi all,
So I've reinstalled my 1200GTO in our backyard observatory after long stint a remote observatory. A couple of weeks ago, for whatever reason, drift aligning using PemPro showed I was waaay (> 3 degrees) off in azimuth. The only way I could see to get close was to rotate my entire pier. I wasn't too happy with that as the mount was fully loaded. I was also puzzled as the pier's legs were resting on cutouts in our floor that helped me roughly polar align.
When I had everything off, I realized that the 1200RPA's set screws were pretty loose, and more importantly, the Azimuth Adjuster block was scewed way to the east. I needed to adjust west, so I moved the block accordingly.
Drive aligning again this past weekend was still a bummer. I was still off in azimuth after fully adjusting as far west as I could. I'm only 40 or so arc-minutes off now, so not that bad, but definitely not as close as I'd like.
So anyway, is there a way that I can shift that azimuth adjuster block a little bit more without having to take the entire mount off?


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