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  1. #1
    Starboard's Avatar
    Starboard Guest

    Default Dobsonian mount - azimuth bearing question



    For the most part, the bearings are smooth. But, when using higher
    powers and tracking an object overhead, the azimuth bearing seems
    slightly jerky. It's smooth while you are slewing, but, if all you want
    to do is just nudge it a tad, you must first overcome the friction
    between the nylon (or Teflon, not sure what it is) pads and the black
    Formica underside of the upper platform mount.

    I called Orion a few minutes ago to ask if there is an approved
    lubricant (either wet or dry) that could be used on the Formica
    surface. I was asked to kindly call back in an hour when the "techie"
    comes back. I suspect when I talk to the "techie" that he will
    recommend graphite, Vaseline, or some type of silicon product.

    Any suggestions while I wait to speak to "techie?"


  2. #2
    Jan Owen's Avatar
    Jan Owen Guest

    Default Dobsonian mount - azimuth bearing question


    "Starboard" <errol_winn@yahoo.com> wrote in message
    news:1137197073.968820.86610@o13g2000cwo.googlegro ups.com...

    Auto wax is one substance that has been used a lot...

    True virgin Teflon is better than Nylon, but in either case there is
    *some* stiction to overcome; however, after that, movement should be
    buttery smooth... I've had a number of Dobsonians, and only used wax on
    one of them, and even then, only once. But all of mine had Teflon
    bearings (as did the one I used wax on).

    On the other hand, I know someone else who added Teflon to avoid a similar
    issue, and Teflon didn't solve _his_ problem...

    --
    Jan Owen

    To reach me directly, remove the Z, if one appears in my e-mail address...
    Latitude: 33.6
    Longitude: -112.3




  3. #3
    Phil Wheeler's Avatar
    Phil Wheeler Guest

    Default Dobsonian mount - azimuth bearing question

    Starboard wrote:


    It's not uncommon for folks to fuss with the bearings, az and alt, of a
    Dob. There should be websites on the subject. One tip I saw was to cut
    washers from plastic milk containers and put them over the center bolt
    between the base and the rocker box.

    Others replace the supplied bearings with slicker materials .. example:
    There are stick-on furniture sliders available at hardware stores.

    Do a google search on 'dob az bearing' (and like that) and see what you
    find.

    A Dob is a neverending project :-)

    Phil

  4. #4
    Starboard's Avatar
    Starboard Guest

    Default Dobsonian mount - azimuth bearing question

    FYI,

    Orion techie recommended Pledge furniture polish.

    Errol
    NOLA


  5. #5
    Chris L Peterson's Avatar
    Chris L Peterson Guest

    Default Dobsonian mount - azimuth bearing question

    On 13 Jan 2006 16:04:34 -0800, "Starboard" <errol_winn@yahoo.com> wrote:


    What I did was place a shimmed ring bearing- a lazy susan bearing- in
    the center of the table between the base and the rotating table. This
    lifts a bit of the weight off the teflon bearings and makes for buttery
    smooth rotation with essentially zero stiction.

    _________________________________________________

    Chris L Peterson
    Cloudbait Observatory
    http://www.cloudbait.com

  6. #6
    Edward Erbeck's Avatar
    Edward Erbeck Guest

    Default Dobsonian mount - azimuth bearing question

    "Starboard" wrote:


    Errol, You are fighting leverage (and possibly other things - but first
    let's look at leverage). When a Dob. Style Scope is vertical, rotation
    becomes more difficult because you no longer have a lever working in your
    favor (hence "Dob's Hole"). Simple no cost solution (given it works well at
    all other times) is to just wait until the object moves to a lower position.
    As to lubrication options try to avoid ANYTHING that could collect and
    store dust and/or "grit" as they will slowly both grind away and in doing so
    embed crud into the bearings that will over time make the whole situation
    worse!.
    A simple test to see if your bearings are working properly is to set your
    Scope at say 70 of 80 degrees above horizontal and pull it at a 45 degree
    angle. If the force required is equal in both vertical and horizontal you
    are better off living with it than making one better than the other.


    Crazy Ed


  7. #7
    Starlord's Avatar
    Starlord Guest

    Default Dobsonian mount - azimuth bearing question

    You could use something like Mop & Go, it is fast drying and makes the floor
    very slick.


    --

    The Lone Sidewalk Astronomer of Rosamond
    Telescope Buyers FAQ
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    "Starboard" <errol_winn@yahoo.com> wrote in message
    news:1137197073.968820.86610@o13g2000cwo.googlegro ups.com...



  8. #8
    Starlord's Avatar
    Starlord Guest

    Default Dobsonian mount - azimuth bearing question

    I've tested my 10 inch dob that came to me last month, it has just the
    teflon pads and it works just fine in the dob hole and the design of my B8
    dob makes it dead simple to work the dob hole area.


    --

    The Lone Sidewalk Astronomer of Rosamond
    Telescope Buyers FAQ
    http://home.inreach.com/starlord
    Astronomy Net Online Gift Shop
    http://www.cafepress.com/astronomy_net
    In Garden Online Gift Shop
    http://www.cafepress.com/ingarden
    Blast Off Online Gift Shop
    http://www.cafepress.com/starlords




    "Edward Erbeck" <Ed@CrazyEdOptical.com> wrote in message
    news:BFEDA708.1CDB%Ed@CrazyEdOptical.com...



  9. #9
    Phil Wheeler's Avatar
    Phil Wheeler Guest

    Default Dobsonian mount - azimuth bearing question

    Starboard wrote:

    Lemon or unscented? :-)

  10. #10
    Phil Wheeler's Avatar
    Phil Wheeler Guest

    Default Dobsonian mount - azimuth bearing question

    Starlord wrote:


    This from the guy having a Dob with wood-on-wood bearings, lubricated by
    desert sand .. eh, Dennis?? :-)

 

 
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