Cleaning newt mirror?

[iceman]

Hey guys.

My 10" mirror is starting to look a bit dirty.. a few sessions of dew have left it a bit dirty looking, plus there's some dust and marks on it that are just crying to be cleaned off.

Now i've read about using distilled water and just rinsing the water and spotting it with a piece of paper towel to soak up the droplets, so that's fine, i'll do that.

What about actually taking the mirror out?

Do I have to touch the collimation screws at all (and the other 3 that lock it in place)?

Or do I need to undo the phillips head screws that circle the outside of the bottom rim?

What's going to stop it from falling on the ground? :eyepop:

Thanks guys appreciate your advice.

[gbeal]

Ice,
mine is a homebrew so will differ, perhaps. Best idea if in doubt is to remove the mirror completely, but in my case I simply wash it in the laundary tub, complete with cell (University Optics alloy cell).
I partly fill the tub with cool to luke warm water, and a slurp of dishwashing liquid (less not more). Allow the dust/crap to soak for a while then swill it off and lightly/gently swab the surface with cotton wool.
Tip on an angle to drain/dry, and then get the last drops with the tissue/towel.
Care is required, but more so you don't drop it.

[Mick]

To clean or not to clean? A little bit of dust won't hurt, Ice. I don't look down the tube of the dob for fear of getting that cleaning urge. If you are going to clean it set everything up before you start and just take your time. I've only cleaned the corrector plate of my Lx90 once in 4 years and that was to remove pollen. Being relaxed and taking my time made it run smooth. Just my thoughts.
:astron:

[gbeal]

Ice,
I'll echo Mick's comments, and add to them.
I have cleaned the 10" mirror perhaps twice in about 6 - 7 years.
Mostly it is spider webs within the tube (I have a series of ring baffles throughout the length), that I have to chase away. As Mick says a bit of dust isn't bad, unless maybe it contains airborne contaminants?
Gary

[ving]

you could try all the above or just use steel wool like i dohttp://www.click-smilies.de/sammlung0304/cool/cool-smiley-011.gif

JUST KIDDING!
DONT USE STEEL WOOL!!!http://www.click-smilies.de/sammlung0304/aktion/action-smiley-036.gif

there are plenty of sites that tell you how so my sugestion is seek and readhttp://www.click-smilies.de/sammlung0304/aktion/action-smiley-036.gif

[Starkler]

Mike I have taken my mirror out for centre spotting before so I'll run through whats involved.

You WILL have to re-collimate the primary mirror , there is no getting around it.

Unless the mirror is horribly dirty or dusty it should just be left alone. I have had my scope for 1 1/2 years stored in the garage and I'm considering now cleaning mine for the first time.

1: Lay your tube on the floor and undo the four screws which hold the mirror cell to the tube.

2: Carefully ease the mirror cell out of the tube. Mine was tight as all getout and had to be persuaded, yours may be different.
2a: Now is a good time to check the altitude bearing mounting screws. Mine were loose and needed tightening from new.
2b: Now is also a good time to flock the bottom end of the tube.

3: Sitting the mirror cell on a clean towel on your living room table , undo the eight screws that hold the rubber mirror clamp blocks in place and remove.

4: Carefully ease the mirror up and out from the mirror cell. Mine was a very snug fit as the cell is padded with thin cork strips which keeps things snug.

5: If your going to recollimate anyway, you may as well dissassemble the mirror cell and ditch the metal plate. This will aid cooling time for the primary mirror.

6:Give the mirror a good soak in a clean container with just a minute amount of dishwashing detergent.

7:Clean by very gently dragging a cotton ball across its surface, turn it over, do another stroke, then discard for a fresh cotton ball. Do not wipe with an already soiled cotton ball, or press down with any force onto the mirror surface.

8: After cleaning, rinse well with tap water, then rinse again liberally with distilled water and stand the mirror on its side on something absorbant to drain (well away from pets, children or any other potential accidents :D).

9: Carefully blot any water beads with edges of paper towel.

10: After drying, refit mirror to cell and refit the rubber mirror clip blocks so that they only just touch the mirror, without putting any tension on the glass. Clips being too tight are a common cause of astigmatism. Dont worry your mirror cannot fall out :)

11: Refit mirror to cell taking note of the notch in the cell to accomodate the seam of the tube and recollimate.

Good luck !
Really its not hard :D