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A bit of trouble with a G11 Any suggestions?

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#26 mdowns

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Posted 24 October 2012 - 09:16 PM

And one more.I feel certain that with some steady air I'll get some good shots with the setup........

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#27 Steven

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Posted 25 October 2012 - 02:09 AM

...I've owned more gems than I can really recall including a gm8 but have never had a mount so extremely sensitive to weight...


I have the same mount as yours (made for Celestron) and it is not that sensitive to imbalance. I suspect the oldham coupling is slipping. Take off the cover to confirm and if that is the case, tightening the set screw will fix it. Hope it helps.

#28 mdowns

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Posted 25 October 2012 - 06:31 AM

Steve,
What is the oldham coupling and under which cover can I find it? thanks!

#29 Startraffic

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Posted 25 October 2012 - 08:46 AM

Steve,
The Oldham coupler is in between the gearbox and the worm. It is under the worm cover. Looking at your mount picture, the RA worm is the rectangular box above the altitude adjustment knob. The cover is held in place by 2 small set screws (1/16th IIRC). Loosen those screws (you don't need to remove them), take the cover off & you'll see the Oldham coupler. Posted Image
IIRC the allen wrench is a 0.5mm and the set screws are easily rounded out. I put a piece of WHITE electrical tape on my wrench so it would be easier to find when it gets dropped . When it does get dropped it immediately changes its' state into dark matter and becomes undetectable to any & all means of locating it, in direction proportion to its' need, raised to the power of the distance from the nearest available replacement as measured in Angstroms. DAMHIKT
FWIW The Oldham coupler is not a great design. It is inexpensive, & fairly durable in low torque situations, but it can slip, bind, or induce a harmonic stiction error if it isn't aligned well. (This stiction can & will drive you nuts if it happens to you. Completely erratic. I happened to notice the HMMV center intermittently skip.) I trimmed off a tiny piece of sprue left on mine & never happened again.
The new OPW uses a different type of coupler that works well, but really needs a solid round shaft to hold onto. The worm is fine but the gearbox has a flat spot milled into the output shaft. I made a piece of aluminum that fit on that spot & put it in. No troubles with slippage since.

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#30 Cotts

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Posted 25 October 2012 - 10:36 AM

he told me that first,the 12V,.500 amp power supply is indeed adequate for the mount.


I'm glad you have solved your difficulty. I am, however surprised by the above. It must be true if Scott says so. If you use a 3 or 5-amp power supply with proper filtration and voltage regulation your mount's motors will be happier and you can run your dew heaters from the same power supply.

I will stand by my comments that those plug into the wall power supplies are often of minimal quality with poor regulation and filtration and that long runs of 12VDC are a poor idea..

Your moon pics are terrific, BTW.

Dave

#31 Steven

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Posted 25 October 2012 - 03:57 PM

Steve,
What is the oldham coupling and under which cover can I find it? thanks!


StarTraffic illustrate and explains it well. In your case, I suspect the oldham is slipping against the motor/worm shaft. After you remove the cover and with the drive on at 16x, press on RA and watch carefully whether the coupler slips.

#32 mdowns

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Posted 25 October 2012 - 04:55 PM

I honestly agree with your comments. Scotts answer simply ruled out one immeadiate concern.In time,I'll definitely upgrade the power supply per yours and others suggestions.Thanks Cotts!

#33 mdowns

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Posted 25 October 2012 - 05:06 PM

Startraffic,
Thanks for all the info,insights and the pic. At least now I have something to target.It's raining here now(first rain on the telegizmo 365) so this will have to wait till tomorrow,Saturday or Sunday. I may pick your brain and Steve's again if you both don't mind.

#34 Steven

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Posted 25 October 2012 - 06:28 PM

Startraffic,
Thanks for all the info,insights and the pic. At least now I have something to target.It's raining here now(first rain on the telegizmo 365) so this will have to wait till tomorrow,Saturday or Sunday. I may pick your brain and Steve's again if you both don't mind.


Better to do it inside. It is more comfort and avoid loosing little parts like set screws in the dark!

#35 Startraffic

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Posted 29 October 2012 - 01:20 PM

Steven,
That illustration is from the Losmandy site so I should've given credit there. Doing it inside is a good thing unless you have a clear floor outside. I have an POD so I do everything outside. The setscrews don't have to be removed, just loosened, 1/2 a turn is plenty. If they loosen on their own, then a tiny dab (I use a blunt toothpick) of the red or blue Locktite will cure that problem.

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