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I am unable to fully tighten the dec axis clutch on my GM811G. There's a quarter-inch play in either direction when the clutch is tightened down. Does anyone have a similar problem and is there a fix?

La G11T es una opcion real no cabe duda que ella si lo podria soportar con eficacia. Cierto es que el telescopio, mas guia y camaras se va de peso para fotografia. Es complicado elegir la montura, lo que tengo claro es que sera losmandy. Lo consulto con la almohada pero no me responde nada claro.

David, et al,

I share your preference for PDF.

But for future reference, it is easy to capture the HTML by copying and pasting into Word (or just about any text editor).

You can then save as a PDF or Word (amongst others) format. Plus in Word you can annotate the material if you wish.

No need to scan, and the result will usually be more compact and can be annotated.

Best regards,

Mark Christensen

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Hi!

Maybe, just maybe, you have the same spikes as I have, Jamie. See the attached guide-log. First run is interestingly enough without spikes, 2nd and 3rd have spikes, all in the same direction (I still have no clue about how to be sure which direction this is....) - and all RA spikes seems to happen when given a small guide pulse in the direction of the spike.

4th run same pattern + some DEC + RA spikes. In these, the RA spike is not simultaneous to a pulse guide. Since these are in both RA and DEC, I guess this is something different. So I do not focus on them now.

So my thinking: the RA-only spikes, seemingly triggered by a guide pulse, could depend on RA backlash and the scope too well balanced - so the small guide pulse sends the scope off an unproportional distance, so to speak across the backlash. Does that seem reasonable? It can be tested by Michael's suggestion of hanging an extra weight on the eastern side and see what happens. Need to wait for clear skies and then try (too bad this can not be tried during the day, and when cloudy).

I'm guiding with a 600 mm guidescope with a Lodestar, piggybacked on a C11, on a G11 with untucked motors, OPW and high precision worm. I have PEC enabled (have tested on and off, seems not to affect these spikes now).

When I run PemPro of guiding assistant in PHD2, there is a very smooth curve and no spikes like this. Which I think would rule out anything like dirt in the needle-bearings or on the worm, etc. These spikes seems only to occur when actively guiding. Again: makes sense?

Maybe this resonates with your situation, Jamie?

Magnus

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David,

Has anyone got a scan of this?

Thanks,
David

Good to know, Michael. The brass worms may wear over time, as they are softer than the ring gears, but at least they won't be corroding as well:).

My original RA brass worm seems to have an slight indentation where it meets the ring, but the threads have been worn smooth which is what we all want. I am wondering how many thousands of hours we can get out of one, before metal loss might be a problem. At least we know we can replace them when the time comes.

Hello David,

You have a pretty big telescope and you must be an astrophotographer considering the specifications. As Brendan said, after adding accessories, you are getting pretty heavy, and might be getting close to the maximum capacity of the G11G. But it should still work out for you.

But if you can afford it, the G11T might be a better choice for you with the larger weight capacity. And with the Titan, you have more room for additional items like a larger guide scope, bigger camera, and any piggyback secondary telescopes too.?

Best Regards,

John

Keith, I think the discussion was regarding time and latitude/longitude settings. These can be set from the driver. Custom site can also be selected from the driver. Either one can be set to update automatically, when the driver connects to the mount.

Regards,

? ? ? -Paul

On Sun, Apr 4, 2021 at 09:00 AM, Davidspain wrote:

Hola, tengo un newton 300mm f/4 y queria preguntar si la G11G lo soportaria adecuadamente, pesa 24 kg el telescopio.?

Hola David, el g11g tiene una capacidad de 27 kg, pero debes tener en cuenta los extras como la cámara, el visor de guía, etc.



Un Newtonion de 300 mm dará mucha flexibilidad diferencial

Sorry....google translate. ;)
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Brendan

Henk,

The bearings are pretty inexpensive, about $10 (US). Since the 76 second error is related to the bearings, new will be best. Old bearings could have wear spots or may have been slightly warped during original installation or removal. If the block seats were too tight, or changed with temperature (as per Michael's explanation), the outer races could be slightly out of round, or bent. This may cause the ball hang ups, as per the white paper. So the same bearings may retain their deformations, even after you change the seating or springs tensions.

As per Michael's advice, it seems the right bearing is the one to float, to allow Belville washer tension, but also to permit some slight flex along the worm axis. The left one should remain as the solid base. I suppose that seating could be loosened as well to prevent some crushing, but I have not heard much discussion about that. But installation of the left is still critical, being careful to evenly tap into place without pinching, so tap or push slightly around the edges gently to wiggle into place.?

I have followed Michael's instructions, and read the whitepaper and discussions, so I am following the instructions of those experts. Figuring this out on one's own would take a quite a bit of study and research. Good luck.

Regards,

John

Note that as per the Gemini.net documentation, one can't configure site info in the driver:

"Note: It is not possible to configure the preprogrammed sites via the driver; this must be done via the physical Gemini hand box (Gemini-1) and using the Web interface for the Gemini-2 and Gemini-2 Mini."

Keith

Perhaps it's worth asking Roland in the AP forum as to from where his recommendation stems - surely he must have done some experimentation or has seen evidence of this?

Keith

There is actually another option, namely to stack every 10 seconds and use no PEC or autoguiding at all.? That way the errors will never exceed the errors in a 10 second interval.? The technology is available, I know someone who does this with his ATIK.? Perhaps the live stacking of Sharpcap can do this for general cameras.? If not now, some time in the near future.? The computing power should be there already, it is just a matter of time until people start wanting this feature.

Thanks Ian, that's good to know.? I think the inner block was misaligned because I had to make the flex couplers of my stepper fit, and those have some stiffness while the motor and worm were not perfectly aligned also.? Let me see if I can do a better job at that.??

Maybe an autoguider can handle it but I started looking into it because I get over 1" RMS and I expect this mount to do better.?

I added the spring loading because the mount had more backlash than I liked.? Tightening the worm would simply lead to the mount binding up, I could feel it manually.? The ring gear is just not round enough to have zero backlash.? Looking at the first graph (spring loaded configuration), it doesn't look much better than the second but at least it keeps the mount from binding up when slewing.

So I can pick my poison.? I can align the blocks as best as I can, tighten them, abandon the spring loading, allow backlash (hardly a problem for RA when tracking) and put up with the 240 second cycle and the backlash for slewing and plate solving.? Or I can keep the spring loading, improve it so the 75 second cycle is more regular than what we see in graph 1, and put up with the 75 second cycle.? Or I can drill out the holes in the blocks, apply Belleville washers and spring loading.? Let me try the non destructive options first.?