For G11 owners

[multiweb (Marc)]

Been doing a lot of mount cleaning over the long week-end and a bit more reading. I don't know if this has been posted before but I found it a real good quantitative article. Although it is geared towards the new single block worm there's a lot of info and measurements about the whole standard set-up too so it gives you a good understanding of what's going on and what to look for, even with a two blocks arrangement.

[Hagar (Doug)]

Thanks Marc, I had a look at this site last night. My guiding has turned to crap after installing new gearboxes to the mount. The old ones were stuffed totally.
This is another very interesting site about tunning a G11. http://www.wilmslowastro.com/tips/mclennan_gbox.html

[multiweb (Marc)]

There is a chapter about the change of gearboxes. Apparently the McLennan models didn't improve anything dramatically. Same goes for the ceramic bearings. I think a lot of the noise and spikes come from the weakest link: the user setting up the worm meshing and end blocks. Obviously the biggest advantage of the Losmandy one block is that the gearbox, couple, worm and end blocks are all inline. Using an oldham coupler is pretty forgiving but using a semi rigid model means your gearbox has to be spot on. I still believe that with a bit of shimming and tweaking you stil can get a good result. I got mine down to +/- 2.1 arcsec without PEC so it's possible.

[JohnH]

Thanks for the link Marc, very interesting read....

Is that +/- 2.1 " with a one piece or the older two piece worm setup? I am tempted again (was with the ovision) but my DIY mechanical skills are not the best and would need this fitted/tuned....

[multiweb (Marc)]

Originally Posted by JohnH

Thanks for the link Marc, very interesting read....

Is that +/- 2.1 " with a one piece or the older two piece worm setup? I am tempted again (was with the ovision) but my DIY mechanical skills are not the best and would need this fitted/tuned....

No ovision or one block. Just the standard worms with the two end blocks and a bit of shimming /adjusting. Once you get used to it you can get it right no problem.