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AT12RCT RC Primary Mirror Rough Beveling/Chips

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#1 Monkeybird747

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Posted 19 January 2020 - 11:57 AM

Second owner of this scope. Original owner shared an email from Astro-Tech stating that these GSO RC mirrors typically have this rough beveling on the edge. I also have what looks like a very tiny chip on the extreme edge. Is the “rough beveling” or tiny chip of any concern? I’ve seen where you can use a sharpie over a mirror chip to minimize it’s impact. Should this rough spot at the edge be blackened, or are extreme edge defects of no concern for imaging? The clips (see other post) were visible to the secondary, so my concern is the rough edge will be also. Trying to squeeze out the best performance I can from this RC.

 

 

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#2 charlesgeiger

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Posted 20 January 2020 - 02:04 AM

Yes, the edge was apparently not bevelled properly when ground.  I would certainly felt tip the edge with a black permanent sharpie.  I would also make sure that the mirror clips are felt backed so that they do not add to sparing off of glass.  Be very careful when you clean the mirror that you #1, don't cut yourself or #2, further chip or spar of the edge.  A further remedy (would be to lightly go around the edge of the mirror very lightly and slowly with a knife sharpening stone using water).  Immediately wash off or spray off any grit or glass that should come off.  Of course you would have the mirror completely out of the cell and resting on a solid surface with optical side up and using the stone at the same angle (about 45 degrees) and always pushing lightly from the direction of the center of the mirror outwards again just on the bevel.  

Good luck and let us know what you will do.

charlie


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#3 Monkeybird747

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Posted 20 January 2020 - 02:16 AM

Thanks Charlie, I may start with the sharpie.


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