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Is my guidescope hurting my LX90 GPS? What to do?

Last post 04-11-2009, 9:36 PM by ChuckR54. 9 replies.
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  •  04-05-2009, 2:33 PM

    Is my guidescope hurting my LX90 GPS? What to do?

    Hello, everyone,

    You can see my setup here: http://autostarsuite.net/photos/fritzo130/picture18834.aspx

    There are 3 pictures (for some reason it automatically rotated the images horizontally when I uploaded them, I'll have to find where I can rotate them on the website).

    I have an Orion ED80 as my guidescope.

    At first I tried to use 8 lbs of counter weight on the Losmandy 3d weight system. I then balanced it according to Dr. Clay's method. However, when I tried to move it, the poor thing just whirred and struggled to move and I was very concerned.

    After that I have been balancing it with just 4 lbs of weight because I am scared to hurt the drive. But I may be in fact hurting it right now.

    I notice my goto's never work anymore, it is very hard to polar align, and I cannot move my telescope in right acension in one direction (this is because the guidescope is sitting on the right edge of the tube, so I cannot move the scope left).

    I tried to counter this by adding some washers on a string to the left side of the fork mount (on the handle) and that balances it when doing Dr. Clay's method, but it still does not allow me to move the scope counterclockwise without having to help push the fork mount in that direction with my hand.

    Does that mean I need more weight? I know Chuck uses about 10 lbs and he uses the same guidescope. Can an 8 inch LX90 GPS take that much weight?

    Thank you,
    Fritz Laun
    Fritz Laun
    University of Missouri

    LX90 8" GPS
    Orion 80ED Refractor
    DSI Pro I and II
    LPI

  •  04-11-2009, 12:12 AM

    Re: Is my guidescope hurting my LX90 GPS? What to do?

    Hi Fritz,

    I don't know about whether you are hurting your scope, but a well balanced scope does not produce the sort of sounds you describe. FYI, I have roughly the same setup and use 7lb of weight....

    I would re-check the instructions....with a well balanced scope you can undo the ra and the dec and it will just sit there....you can move it with your hand to a new position and it just sits there after that (until you move it with your hand again).....if you can get someone to show you how to balance (i did at my local astro shop when I purchased some new gear, the guys were very helpful - I took in my rig and attached the new stuff I was buying and asked for a lesson!)

    HTH

    Alex

     


    Alex
  •  04-11-2009, 12:16 AM

    Re: Is my guidescope hurting my LX90 GPS? What to do?

    PS - I put my guidescope flush in the middle of the LX90.....this puts the weight in the middle, but it should not matter if you balance it correctly .....

     


    Alex
  •  04-11-2009, 12:40 AM

    Re: Is my guidescope hurting my LX90 GPS? What to do?

    Thanks for the reply!

    Where did you put your finder scope when you put the guidescope in the middle? My finder scope cannot fit into the dovetail fitting on top of the Orion ED80.

    I am now using 7 lbs of weight and it balances when pointed 45 degrees up and facing south as well as facing straight up at the zenith. However, it still moves a little slow when going the direction the guidescope leans on. The goto's are still not very accurate, but better.

    I heard that some people put their guidescopes on the side in order to add a little weight in the direction that it tracks. Maybe it just isn't worth it with all the hassel it brings?

     

    Did you have to add any weight to the side of your fork arms?

    Thanks,

    Fritz


    Fritz Laun
    University of Missouri

    LX90 8" GPS
    Orion 80ED Refractor
    DSI Pro I and II
    LPI

  •  04-11-2009, 1:59 AM

    Re: Is my guidescope hurting my LX90 GPS? What to do?

    I think I will place the guidescope right on top like your setup is. This seems to be the only way it could possibly balance correctly since the weights were not at an opposite angle at the bottom of the scope.

    I will force myself to make a homemade adapter for my meade finder scope to fit on the orion ED80.

    I just need my goto's! Haha.


    Fritz Laun
    University of Missouri

    LX90 8" GPS
    Orion 80ED Refractor
    DSI Pro I and II
    LPI

  •  04-11-2009, 5:25 PM

    Re: Is my guidescope hurting my LX90 GPS? What to do?

    Hi, Fritz

    When you are balanced correctly, the motors only have to work a little harder to get the increased mass moving. For that reason, we usually reduce the maximum slew speed so as to reduce the torque on the gear train.

    If balance is correct, gotos should not be affected at all. Looking at your pictures, it appears to me there is not enough weight, and what you do have is too close to the tube. The weights will need to be much farther out on the spindle to keep the scope balanced when pointed near zenith.

    All that said, I'm confused by the position of things. It appears to me that the forks are rotated 180 degrees from where one would normally have them - is this just for the sake of the photo? (It is almost as if the guide scope is on the underneath side of the OTA?)

    In any case, I would move the guide scope to the centerline of the OTA. Don't worry about the E/W balance, you can easily correct that by strapping an ankle weight to the east fork arm if need be. As for the finder scope, I'm not familiar with the 8" LX-90. It may need to move, or it may not. The stock finder worked out OK on my 10" scope, but it is a fairly tight fit.

    Here are some links to pictures of a couple of  LX90 setups that I know work:
    http://autostarsuite.net/photos/tking2097/picture9853.aspx
    http://autostarsuite.net/photos/ewokvols/picture8810.aspx

    HTH,

    Chuck

    Chuck Reese
    CDIP Certified: Nebula, Galaxy, Solar System, Stars & Clusters Imager
    CDIP Mentor: Nebulae & Solar System Categories
    For information on the Certified DSI Imager Program, see:
    http://autostarsuite.net/forums/1427/ShowForum.aspx
  •  04-11-2009, 5:39 PM

    Re: Is my guidescope hurting my LX90 GPS? What to do?

    Chuck,

    I just put the guidscope flush on the LX90, now have 7lbs of weight, and it is balanced perfectly. Finder scope is a little tight but it works.

    Are you saying the handles on the fork arms are suppose to point north? The guidescope is on the top of the OTA, the Meade decal is right side up. Is that what you are talking about? I mounted the guidescope on the same side the finder scope came attached to (top).

    However, when trying to move the telescope counterclockwise it still does not perform very well and becomes stuck in several places. Did I burn out a motor? :(

    I am going to replace the batteries today and see if that works.

    Thanks,
    Fritz








    Fritz Laun
    University of Missouri

    LX90 8" GPS
    Orion 80ED Refractor
    DSI Pro I and II
    LPI

  •  04-11-2009, 6:01 PM

    Re: Is my guidescope hurting my LX90 GPS? What to do?

    Update:

    The new C batteries did it... I was going to have a heart attack if they didn't fix the problem. I live very far from any type of dealer and would have to ship the dang thing to get it fixed. WHEW!!

    Here is a picture of the telescope in the polar home position:

    http://autostarsuite.net/photos/fritzo130/picture18861.aspx

    I apologize for the orientation of the photo, I still haven't figured out why the website automatically rotates the image to be horizontal and I cannot find any options on the website to rotate it back.
    Fritz Laun
    University of Missouri

    LX90 8" GPS
    Orion 80ED Refractor
    DSI Pro I and II
    LPI

  •  04-11-2009, 6:21 PM

    Re: Is my guidescope hurting my LX90 GPS? What to do?

    Hi Fritz,

    Glad to see that the new batteries fixed it! Personally, I rig up an 18AH battery to my rig. It takes a long time to go flat and it means that there is a constant power source when it comes to things like gotos, training etc...

     


    Alex
  •  04-11-2009, 9:36 PM

    Re: Is my guidescope hurting my LX90 GPS? What to do?

    That looks right - you should be good to go!

    You rotated the camera (as any good photographer would, to fill the frame). The website doesn't know that, it assumes you held the camera right-side up in landscape mode.

    Good luck tonight!

    Chuck

    Chuck Reese
    CDIP Certified: Nebula, Galaxy, Solar System, Stars & Clusters Imager
    CDIP Mentor: Nebulae & Solar System Categories
    For information on the Certified DSI Imager Program, see:
    http://autostarsuite.net/forums/1427/ShowForum.aspx
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