Cleaning an SCT primary mirror

Anyone tried to clean the primary mirror in an SCT? Mr Lillis?? Is it even recommended to DIY this?

Now why on earth you would want that?Is it that dirty over there?
As far as i heard primary of SCT is machined at factory and its not supposed to be touched under any circumstances as you probably ain't going to get collimation afterwards.
I use to own SCT and after reading several threads about maintenance got a clear impression that its not worth it...

:lol: :lol: hey Kieran
and yip, I've had to do it only once in my 12 years of owning a 12" lx200, only about 2 years ago.
It had a fine layer of dust and a small cobweb on it and didnt want it to stick.
I took off the corrector plate, leaving its cell on the scope, I then turned the focus to move the mirror as near as possible to the front of the scope (easier to reach), I then very very carefully cleaned the mirror using surgical cotton and distilled water, like any other mirror, except you really cant soak it cos its still in the OTA.
You could take the mirror out of the OTA, but it requires the disassembly of the focuser and I wasnt getting into that. SCT primary mirrors are not collimatable, if you take it out, then you must be sure you put it back in the exact same way. There is nothing special about a SCT primary mirror compared to a dob mirror interms of how you treat it.

You need to be careful about the usual no brainer stuff, like been damned carefull about where you put the corrector plate while out (chip it and it's a trip back to meade to get 2 mirrors and a corrector installed), making sure the corrector goes back in exactly the same way it came out (rotation wise), not leaving any cotton floating around inside the tube afterwards.

Mirror is now factory perfect

I just knew that if anyone had attempted this then it would have been yourself Dave :rock: . It pretty much confirms the method I'd heard before and I know that Damian Peach has taken his apart to clean. Mine is now 6 years old and never completely sealed due to the CCD on the back which has a collimating flange and thus an air gap. I happened to shine a torch down the tube last week and YUK!

It's a job for some day when the kids are at granny's house and well out of the way.

Cheers

well good luck with it Kieran, its not a difficult procedure. :scope:

Yea, I've done it before also.
It's amazing how clean the mirror can look after using the powerwasher....