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Uneven mirror cell.

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#1 Universe observer

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Posted 17 April 2024 - 12:38 AM

Is it unusual to have a seemingly asymmetrical mirror cell? I'm unsure as to whether I have knocked the bottom of the tube, or if it came like that from the factory.

I notice I sometimes lightly bang the tube against the dobsonian mount when pointed up overhead. Any ideas what I can attach to the mount to soften the knocks and stop the primary from potentially being knocked out of collimation?

 

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Edited by Universe observer, 17 April 2024 - 12:39 AM.


#2 JohnTMN

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Posted 17 April 2024 - 12:50 AM

 I'm unsure as to whether I have knocked the bottom of the tube,

Friend,

Your shared photo is undefinable,?

Please help us help you,,

Gee, a quarter section of something is touching  it's mount,,

And then? A little help here?
 



#3 Universe observer

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Posted 17 April 2024 - 01:00 AM

Friend,

Your shared photo is undefinable,?

Please help us help you,,

Gee, a quarter section of something is touching  it's mount,,

And then? A little help here?
 

There is a small looking dent roughly at 7 o'clock. I believe that could be caused by the knocking against the mount. I was wondering if I should apply some padding to soften the blows.



#4 Universe observer

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Posted 17 April 2024 - 01:02 AM

It is on the lip of the mirror cell and admittedly pretty minor.



#5 shohin

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Posted 17 April 2024 - 02:01 AM

So I think we're looking at the bottom end of the OTA, where the cell attaches to the tube. I see the seam line in the tube and a couple of the screws that hold the cell in place.

 

The tube goes slightly out of round when the screws are tightened down. The cell assembly isn't a perfect fit into the tube so there's no way to avoid that. But that shouldn't be affecting the mirror inside. The mirror inside sits on a platter suspended by springs. I think you're OK.

 

If you want to prevent the cell from bumping into the inside of the rocker base you can get one of those stick on rubber pads from the hardware store.



#6 Astro_In_Tampa

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Posted 17 April 2024 - 02:09 AM

That's exactly how the base of my AD12 looks too. Cosmetically ugly, but functionally irrelevant. 



#7 Universe observer

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Posted 17 April 2024 - 02:17 AM

So I think we're looking at the bottom end of the OTA, where the cell attaches to the tube. I see the seam line in the tube and a couple of the screws that hold the cell in place.

 

The tube goes slightly out of round when the screws are tightened down. The cell assembly isn't a perfect fit into the tube so there's no way to avoid that. But that shouldn't be affecting the mirror inside. The mirror inside sits on a platter suspended by springs. I think you're OK.

 

If you want to prevent the cell from bumping into the inside of the rocker base you can get one of those stick on rubber pads from the hardware store.

Yea. It's warped over the edge of the mirror cell. I'll be sure to grab some rubber pads. Thanks for the reassurance.



#8 Universe observer

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Posted 17 April 2024 - 02:40 AM

That's exactly how the base of my AD12 looks too. Cosmetically ugly, but functionally irrelevant. 

That's good to know. I only realized the other day, and it looked kinda bizzare to me as most of the bottom edge is pretty uniform.

 

Btw nice scope,  I would have grabbed one that size too if I had the room for storage.



#9 phottomatt

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Posted 17 April 2024 - 03:59 AM

I put a piece of 1" thick weather stripping there that I had laying around, works like a charm for light bumps.

#10 Astro_In_Tampa

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Posted 17 April 2024 - 04:46 AM

That's good to know. I only realized the other day, and it looked kinda bizzare to me as most of the bottom edge is pretty uniform.

 

Btw nice scope,  I would have grabbed one that size too if I had the room for storage.

Thanks. If you ask my wife, we don't have room for it either. Interestingly enough, every time I ask her which toys from her daycare I can throw out to make room, all I hear is crickets. I'll admit it's not attractive as a living room coffee table, but c'mon... I don't think 4 sq ft of floor space out of 2500 is too much to ask. 

 

As for your scope... I put a shower cap on the primary mirror end of mine to keep out the critters. Works really well and I recommend it. 




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