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Declination setting circle calibration problem

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#1 Duane Frybarger

Duane Frybarger

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Posted 20 April 2009 - 07:35 PM

Hi,

I just bought a used Orion Skyview Pro EQ Mount. After I calibrate the declination setting circle and tighten both set screws, the circle will move as I move the mount in the declination axis. Has anybody experienced this problem and/or has a possible solution? The RA setting circle works perfectly - I don't even have to tighten the set screws.

Thanks in advance and clear skies!

#2 hudson_yak

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Posted 20 April 2009 - 09:18 PM

First of all, do you mean move relative to the saddle when you release the Dec lock and rotate the mount in Dec by hand? Note that it is normal for the Dec circle to move relative to the saddle by turning the Dec Slo-Mo control on this mount (there is quite a variety of ways mounts choose to handle the Dec circle, but that's how this one does it).

If the former, does it seem like the circle is being pinched in its groove? There should be some amount of "slop" where you can move it up and down freely 1mm or so when the set screws are not tight.

Mike

#3 Duane Frybarger

Duane Frybarger

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Posted 21 April 2009 - 09:04 AM

Mike,

Thanks for the response. Yes, the circle moves in relation to the saddle when I release the Dec lock and move it by hand. If I use the slow motion knobs (locked or not), the circle stays put. As far as play in the groove, there is about 1mm of play on one side of the groove (by the worm gear) but there is no play at all on the other side where I lock it down. I guess the quick fix is just use the slow motion knobs for all movements. Please let me know if you have any ideas for a permanent fix so I can move the Dec axis by hand and maintain calibration.

Thanks again and clear skies!

#4 hudson_yak

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Posted 21 April 2009 - 09:33 AM

This web page shows some tear-down pictures for the SVP. When I asked about pinching I meant laterally across the ring, was it being pinched between the saddle part of the mount and the part below.

As the pictures show the ring setscrews push into a part of the mount that moves with the saddle when the Dec is unlocked. So it's hard to understand how the ring would not move with the saddle, unless it's being dragged upon by the lower part of the mount due to pinching.

Mike






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