Cleaning a Mirror

[Myrk511]

Hi People Who Know Things,

I’ve acquired my first dobsonian, an old Celestron Starhopper 8.

The primary is borked. I am going to give it a clean to get the most I can for now and wonder how to get it off the cell. I’m not keen on dunking the cast iron back in the water.

Does anyone know how it comes apart?

Cheers! Kevin

[mura_gadi]

Sorry more a message to say "wow", that 's my first conical mirror I've seen on ISS since joining...

I see side real trading did sell the TS cell at one stage, if no-one here helps out, they might be able to suggest something.

I have seen very few articles about them, them normally just have a single center bolt for security and another for collimation.


Steve
https://www.siderealtrading.com.au/product/ts-optics-405-mm-f-4-5-lightweight-conical-newtonian-primary-mirror/

[N1]

Agree, these conicals are a bit of a rarity around here. Definitely worth keeping if the figure isn't complete rubbish. If it won't come apart, you could always turn it upside down and just dunk the mirror while leaving the "cell" high and dry. That's what I'd do. Mark the centre while it's out too.

[floyd_2]

Alternatively, if you want to clean the mirror using just the weight of a cotton swab in lightly soapy water (meaning upside down wouldn't work) you could bag the cell and tape it tight whilst cleaning, and just fill the mirror itself with soapy water rather than dunking it. I've cleaned an Obsession 15" in the rocker box using a similar sort of method in the past to keep everything else dry and it was perfect. Pouring demineralised water over the tilted mirror after cleaning would be fine if you had the cell bagged properly.

[Myrk511]

Thank you all for the tips. I’m planning on resilvering the primary when funds permit. I ended up using a plastic bag and rubber bands to keep the metal bits dry and that worked a treat. Then I put it back together without marking the centre… Doh! Ah well, I can practice cursing more the next time I try to line up the holes in the tube with the threads on the cell in a poorly lit garage.

Now, if we’d just get one clear night…

Cheers!