Revelation 12" Dobsonian

[abberation]

I have just purhased a used 12" Dodsonian which doesn't have a manual.

There are a couple of things I would appreciate some guidance with.

The springs which tension the trunion access to the stand have a loop at bottom end. Are the loops used as an aid to attach the springs or are the loops themselves hooked on to the posts protruding from the stand?

I have noticed that when the scope is pointing near the vertical it actually moves freely of its own accord and rests in the vertical position. I was wondering if I haven't connected the springs mentioned above correctly or if the trunnion axis pads that the scope sits on need some attention.

Finally I am not sure if the craford focusser needs some attention or if I am not doing it right. If anyone could point me in the direction of some information on this I would really appreciate it.

[David Smith]

I use the loops to aid getting the spring end hooked over the posts. generally in use I only need one of the two attached as with both attached the altitude bearing is too tight.

Pointing any scope at the zenith (straight up) always makes life difficult but you should still encounter the same level of resistance. It can be disorientating though to know which way to move the scope at high altitude.

If you post more details of the focuser issue would be glad to try and help.

[knobby]

Might be useful reading

Review of Revelation 12

not the same scope but maybe useful as it has a similar 'sprung tensioner'

http://www.astronomics.com/main/documents/orion/orion%2012-inch%20dobsonian%20manual.pdf

or try contacting Telescope house they were the importer a few years ago, they may still have some contacts

Also, bit of a long shot but in this post http://www.popastro.com/phpBB2/viewtopic.php?p=81304&sid=64d433bcc032bd8698d4459402068391 chap that bought a new / boxed Revelation posted his mobile no. / email address. Worth a try ?

Enjoy your scope !

[abberation]

Hi and many thanks for the replies. I think I am understanding the focusser/eyepeice a bit more. I have had some time to see how it appears to work.

With regards to the tensioners, I am not sure if they are only connected up when observing. If this is the case I think this scope may have had them permantly connected (?) and possibly the springs have lost some of their strength, or over time the teflon pads or bearings may have picked up some "contamination" making less friction on the bearings. Only a guess. Thought of giving them a clean with some spirit, but again I would appreciate any advice. It is only the last couple of inches prior to reaching the zentih that the scope has a mind of its own. I even wondered if the springs had lost some of their strength and I could lower the lugs the tensioners sit on.

I have contacted the original importer with regards to teflon pads but they haven't been involved with the manufacturer for some time.

Thanks again for the replies.

[David Smith]

I cleaned the alt bearings on my 10" revelation recently. Just used some Mr Sheen and a duster on the advice of someone on this forum

http://stargazerslounge.com/diy-astronomer/164309-revelation-10-dob-mods.html#post2033538

I found that the bearings had increased friction when they needed cleaning.

On the spring issue, I leave my scope in the horizontal position when I am not using it and have both springs attached to keep it in that position. When I am using the scope I disconnect one of the springs so that it moves more smoothly. My scope is 6 years old now and the springs don't seem to have suffered for being extended most of there life.

Hope this helps.

[abberation]

OK thanks again David. Taking it all in - have even thought about reducing the size of the teflon pads.

However will try cleaning and will let you know how things progress.