Replacing Newt. Secondary

Waxing_Gibbous (Peter) · #1 19-03-2010, 12:45 PM

What's the best way to replace the secondary mirror on a GSO 8" Newt?
Do I remove the whole assembly or can it be done in the tube?
If the former, are there any tips for replacing the spider accurately?
Many Thanks,
Peter

erick (Eric) · #2 19-03-2010, 01:10 PM

Dear Peter

Lay the tube horizontal, reach through the spider with one hand and grip the secondary mirror holder, then undo the central screw (between the three collimating screws) with the other hand. The holder will come off and can be eased out past the spider vanes. A spring and washer may fall off the screw. Just retrieve them for when you replace the secondary.

Only remove the spider if you need to get into the tube with a drill or similar (yes, I've done that!)

erick (Eric) · #3 19-03-2010, 01:13 PM

Next question - do you want to take the actual mirror out of the secondary holder? - EEEEK!

See post #19 in http://www.iceinspace.com.au/forum/s...ad.php?t=31846 for achieving that with a 12" secondary. I imagine it would be similar with the 8" secondary.

Waxing_Gibbous (Peter) · #4 19-03-2010, 10:42 PM

Erick,
Thanks for the tips. Good thread that.
My solution involved an angle-grinder

!
I'm not worried about the existing mirror as it looks like it was cleaned with a 'scotch-brite'. I'm replacing it with a new one.
Ta!
Peter