Ovision on G11

[sadia]

Hi Guys, I believe few of you are using Ovision block on G11. I am quite happy with overall PE with my newly installed ovision but getting about .48 arc sec error in fundamental B. This is much better than original worm but i thought Ovision would remove the fundamental B completely. So question is do you guys get any bump in fundamental B with ovision? May be my meshing is bit too tight and needs to be adjusted!

[netwolf]

I think your refering there to the famous 76second error.

I hope Ranier comes in on this because IMHO he knows more about the issues on the G-11 and how to fix them. Indeed long before anyone else even thought of a solution Ranier had made his own, its unfortunate that he has no drawings of the modification he did. But there are plenty of pictures and his mesages are there in the yahoo groups as a matter of record. There were some critical things he suggested like a Thrust bearing but no one has adopted this in there replacement designs.
Inital post by Ranier
http://tech.groups.yahoo.com/group/Losmandy_users/message/25559
and Pic
http://www.rainerehlert.com/astro/worm/RS-Wormblock.jpg
More pics here in the index page.
http://www.rainerehlert.com/astro/worm/

Edit: this was all done some 5 years ago. I really wish he had kept drawings.

There are many current discussions running on this in the yahoo group and CN forums.

Here is one users report on the Losmandy replacement showing how it has moved to the 80second period post install. Fortunately the 80sec one is easier to remove with PEC for this user.

http://helixgate.net/G11opw8.html

PS: one of these days I will install my Ovision, and that will be right after I setup my mount for the first time in over a year. I wish there was a way to make more time.

[sadia]

Thanks Fahim for those links. I went through some of the articles and decided to give the meshing another go. I allowed a bit more backlash and used a feeler gauge to allow equivalent spacing on both end of the block. Fundamental B (76 sec error) is almost gone (.26 arc sec) and recorded PE is < 1.5 arc sec over 10 cycle @ 800mm FL. Probably I can fine tune it further but I think for my focal length this should be good enough.

[netwolf]

Sadia, thats great news I hope that with some more tuning it can be removed. Have you contacted Ovision about it? See what they have to say about it. Maybe they can make changes to there product to improve it.