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    BillVitez's Avatar
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    Default Help Regarding 6-Inch Refractor Objective & Dew Cover Removal



    Hi All,

    I have a request for advice regarding disassembly of a "home Built" 6-inch f8 refractor I purchased used (a real bargain). I bought it from a close friend of the original builder (built c2011). The builder is now deceased and the owner was a novice. There is no documentation on the build, however the parts used are of high quality. I have just finished restoration of the mount and clock drive (again all top quality parts) and have moved on to the OTA. There are some changes I would like to make to the hardware that is inside the tube near the objective which was not blackened and dent removal on the metal dew shield but have run into an unexpected issue. Although, the OTA seems to have been assembled with various off-the-shelf parts (nothing seems to be fabricated or home machined) I cannot find any screws, fasteners or other indications of mechanical attachment for the dew shield and the collar (hammered metal finish in pewter color) that holds the objective to the main tube ~6 inches OD. The collar OD is ~8 inches at the dew shield end and quickly reduces in size to meet the main tube but there seems to be no mechanical attachment. On the focuser end there are 3 sheet metal screws which hold the end ring to the main tube and 3 machine screws (8-32 suggesting domestic parts) holding the 2 inch Scope Stuff Crayford 10:1 focuser to the end ring. Other screws are apparent for the finder dovetail mount (there are 2) but nothing at the objective end of the scope. I admit that I'm not as familiar with refractor assemblies as mirrored scopes (Newtonians and Cassegrains) and this has me really scratching my head. I enjoy a good "puzzle" but have reached a dead end and need input.

    Experience has taught me not to use force (especially when the method of assembly is unknown and a fragile piece of glass is present) so I need some advice. I've tried to find refractor making parts on the Internet to possibly identify my parts and potentially learn of their attachment method but have not been successful in finding anything at the objective end of refractor OTAs (only focuser end hardware). I could provide pictures (it would be my first time).

    Any assistance and/or suggestions are welcome and appreciated.

    Thank you for reading this.
    Bill

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    Gabby76's Avatar
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    Default Re: Help Regarding 6-Inch Refractor Objective & Dew Cover Removal

    A picture of the lens cell would help considerably, some refractors in this size have the lens cell screwed to the tube so I would try turning the entire cell.
    If it looks like the dewshield is press fit into place it may be glued in place.
    Refractors: Antares 105 f/15, Celestron 150 f/8, Stellarvue NHNG 80 f/6.9, TAL 100RS f/10, TS 102 f/11, UR 70 f/10, Vixen SD115s f/7.7
    Mounts: Celestron SLT w/ pier mod & EQ-3 tripod, Celestron hypertuned CG-5 w/ tracking motor & Argo Navis, Manfrotto 028B w/ Stellarvue M2C, Manfrotto 055PRO w/ 128RC, TAL-1 HD EQ, Vixen SXP w/ HAL-130 SXG & half pier
    Diagonals: 2" Astro-Physics MaxBright, 2" Zeiss/ Baader prism, 2" Baader Herschel Wedge (Photo Version), 2"
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    Amici prism, 2" Stellarvue Dielectric, 2" TeleVue Everbrite
    Eyepieces: A-Z

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    The weakest link in the optical chain is the large nut located directly behind the
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    / camera. - Gabrielle

    Ya gotta keep this Apo/
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    thing in some balance of perspective. Apos are awesome, but long focus Achros aren't that far behind them - Siriusandthepup (CN)

    Refractors kick arse precisely because they don't hide behind excuses. That is, they have no obstructions to hide behind. - Jon Isaacs (CN)

 

 

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