Hello, I am interested in a G11, (there is one in the classifieds with a Onstep, or I would get a gemini version but it is more expensive. However I have been told that these mounts are very complicated to use and require a lot of tinkering. Can you tell me if that is true?? ?I have a IEQ45 Pro and these types of mounts I am very familiar with. I could buy like a CEM70 and use it out of the box. But from what I read, well. again the G11 is hard to use at first.?

Would appreciate your comments to the above. and anything about the Onstep version.

THANK YOU!

Nicholas A. DiSabatino

Hi everybody. I received my new G11T mount this week from Losmandy. I had it out to one of my favorite dark sites a few days ago but the many fires in California and in my own state
made finding stars really difficult. I have gone through a few too many mount issues in the last year and I am hoping I have found a reliable mount for the next decade or so. I have always
been undermounted, but I now have a mount that should be good enough, even for my C14. The price tag for the G11T was almost the max I could afford, but I would have taken out a
loan to get a new Titan, if there were still being made. With my C14 the G11T seems pretty stable, and it should be really good for imaging with my smaller SCT’s. A very kind guy in the
Cloudy Nights forum helped me out with some setup issues and I should be good to go. His name is Jeff also, so thanks, Jeff.

Jeff Marston

Losmandy G11 colleagues,
I recently acquired a "vintage Celestron by Losmandy G11 mount with the Gemini System computer".? Mechanically, the mount needed some TLC.? I decided for a complete end to end take apart and rebuild to fully understand how it was built.? This email is to highlight and share how I solved an interesting problem.? This was that the unloaded motion of the Declination shaft when rotated liked to slowly cork-screw either up or down depending upon clockwise or counter-clockwise shaft rotation.? Additionally the level of hand applied torque was also somewhat uneven when rotated, fully free at times and then "binding", then free again, this was even when the end clutch was removed and the shaft flipped 180 for general checkout, something was just not OK with the behavior of the shaft and bearings.? Eliminating possible causes included a close visual inspection of the shaft and bearings for dings, nicks, dents, etc.? Then I verified the shaft was acceptably straight using a granite surface plate and two Starrett # 278B V-Blocks and and a ~0.00005 resolution dial indicator.? I rotated and measured shaft at bearing point areas and in the center (either side of the shaft hole) and satisfied myself the shaft mechanical run-out was OK.? I then checked the overall state of the shaft diameter using a 1 to 2 inch carbide tipped micrometer with vernier (good for no better than 0.00005 (visual interpolation)), multiple locations of the bearing tracks, in general this shaft measured 1.2500 +/-, did not pick up any signal requiring intervention.??

Next for a more sensitive diagnostic test, I realized I needed to see what was going on between the shaft bearings and the shaft interface while the shaft was rotated.? For this I cleaned all the residual grease off the shaft, and used a black indelible marker (Sharpie) and made a continuous thin uniform band of ink around the perimeter of the shaft, slightly in excess of the track of each of the two shaft bearings.? I then inserted the shaft back into the bearings, and rotated it by hand about 50 turns, pulled out the shaft and visually inspected the wear pattern results.?

One end of the shaft was tracking reasonably perfectly with the bearing surface, evenly, continuously around the full diameter of the shaft, ink was uniformly removed. The other end (clutch end) had three "high" visual wear points on the shaft where the ink was worn away, one wear area was about 1/4 inch diameter, the other two wear areas were about 3/8 inch ellipse with long axis of ellipse parallel to the length of the shaft.? The wear points shown by Black Sharpie ink worn away and surrounding shaft remained black.? Using the micrometer I checked the overall diameter at these locations.? The diameter was about 0.00027 larger than adjacent shaft area, this was the source of the shaft binding.? I used 4,000 silicon wet and dry cut paper into a 1/2 inch strip, about 10 inch long with a slight amount of WD-40 oil on the surface and lapped the shaft at these high points.? This was initially done as a spot polish application about 10 strokes (measured after 5) using a very flat piece of highly polish tool steel ~0.4 x 3 inch as a backing to the paper, this was followed with a total of about 20 lapping strokes (measured after 10) holding the strip tight with thumb and forefinger of each hand and moving back and forth keeping the polishing paper tight.? I cleaned up the residue and placed the shaft back into the bearings.? I have had success, the shaft now tracks very smoothly and uniformly now with even application of torque.? I hope that this helps others who may be experiencing this type of defective behavior.? It also shows that 4,000 grit silicon carbide paper (3-M) is helpful to the level of precision needed.? Time to enjoy the G-11? Cheers John

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When my G11 has had either bad goto or bad tracking, here are the problems I have found:

1. Bad polar alignment.? This is by far the most likely culprit, IMO.? Unless you’ve done a good drift alignment, or correctly used an electronic aid like PoleMaster, that would be top of the list of things to check.? Aside from the physical hassles of dealing with the polar scope, a polar scope gives ?a rough alignment even if you did it perfectly, and if you made a mistake, it’s not polar alignment at all, just a recipe for frustration .

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2. Poorly balanced axes.? This can cause slipping in the clutches, which will throw your goto off, and kill your tracking.

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I am sure there are other possible causes, but these are the simple ones.

?

Mark

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From: [email protected] <[email protected]> On Behalf Of dougwheeler90@...
Sent: Monday, August 17, 2020 8:06 PM
To: [email protected]
Subject: [Losmandy_users_io] G11 Mount Not Tracking Correctly

?

Hey everyone, first post here.

I have used the G11 mount before and had success with it, but this past weekend, it seems like no matter what I tried, I could not get the alignment correct.? I purchased the GPS attachment thinking that would make things more accurate and simple, but that didn't seem to help.? After setting up my mount, I aligned it due north with a compass and waited for sunset to align with Polaris using the polar scope.? The app I have on my phone to match the reticle never seems to be in the same position when looking through the reticle of the polar scope, but I've never had difficulty aligning before.? So after aligning Polaris between the correct lines in the reticle, I fired up the mount and used quick start.? I verified the GPS data with another source and verified the time zone UTC -5, or Central Daylight Time, and ensured the time was also correct, and it was.? However when using the two bright stars to perfect the alignment, (typically I use Vega and Deneb), the GoTo was way off.? It would slew but point in totally different directions for either star.? After using the buttons to slew to the correct position, it still would not go back to the correct spot and then trying to slew back to Polaris did not even work.? I put everything back in the correct position with CWD and all that, all my cameras pointing at Polaris and tried again using Vega and Arcturus, and then Arcturus and Dubhe and never got good results.? All my images ended up with trailing and I was using short focal lengths with relatively short shutter times of 3-4 minutes.? I have previously done 8 minute exposures and had no trailing whatsoever at 24mm focal length on a 35mm full frame.? For this past weekend I had three cameras mounted and balanced, with an 85mm lens, a 24mm lens, and a medium format camera with 23mm lens (18mm full frame equivalent).
I wanted to also do a series of Andromeda with my 600mm lens, but that would have been out of the question since I was getting trails at short focal lengths.
Any recommendations for how to fix this?? Honestly, even if the GoTo doesn't take me to the exact position, I'm fine with using the buttons to slew to where I want to go, but I at least need it to track properly.