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AVX backlash adjustment help needed

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#1 exmedia

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Posted 02 September 2013 - 09:52 PM

I've had the AVX mount for 8 months, used with an 8" Newt and a 102mm refractor, and it's been nearly flawless. 'Nearly' because I've never been able to correct the backlash. No matter what settings I make there is still significant backlash. Up till now I've just lived with it, but I'm thinking of trying out AP and would really like to get this under control. Any suggestions would be very welcome.

Thanks,

Richard

#2 frito

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Posted 03 September 2013 - 01:28 AM

well the best way to combat bad backlash is to adjust the mechanical mesh of the worm gear. settings in the HC just try to compensate for it is all, its not really a fix for it. the AVX is quite similar to the CG-5, but is so new i'm not sure anyone has posted how to's on the dissasembly and adjustment of the mounts mechanics. but it should not be hard to figure out where the worm gear is at on each axis and with some careful toying around using other guides for other similar mounts you should be able to figure out how its adjustment works. on most mounts there will be two allens that lock the worm in place and another two usually smaller allens that push the worm away and tword the ring gear on the axis. you will want to manually move the axis you are currently working on adjusting a full rotation via the worm gear manually to insure there is no binding after adjustments, using the motors to move the axis if the binding is bad enough could result in damage.

at the bottom of this page shows the DEC worm gear mount for the CG-5

http://www.astronomy.../cg5/dec2.shtml

to help get a better idea of how to properly adjust a worm gear try this guide made for the HEQ5 mount, the AVX is probably not at all similar to this mount but the advise in it applies to any mount really and will give you a better idea of what to look for when looking for adjustment screws and lock screws.

http://www.astro-bab...ld/heq5-we1.htm


and here is a video i just found where a guy adjusted the gear-mesh going from the drive motor to the worm gear. judging by what i see there the worm drive system is VERY similar to the CG-5.

http://www.youtube.c...h?v=ORGleQBhkLw

hope it helps, if you get stuck somewhere post up some pictures or wait for others with an AVX that have done the job before to respond, I have only adjusted my CG-5 and my Club's Sirius mount (HEQ5)

#3 RTLR 12

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Posted 03 September 2013 - 02:42 AM

Richard,

The worm gear/ring gear adjustment is easily done and very similar to the CG-5 adjustment Dwayne posted. You also need to check the worm gear end play before you adjust the worm gear. This is also shown on the CG-5 site posted. If you have any trouble, give me a pm and I can help walk you through it.

Stan

#4 exmedia

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Posted 03 September 2013 - 08:55 AM

Thanks guys. If I were actually mechanically gifted and actually had tools and a place I could do all that that wasn't my kitchen table it would be great. But, I'm not and I don't. Guess I have to wait until some enterprising soul offers AVX mount 'tuneups' and get him to do it.

Seriously, thanks. I at least now know what's causing the backlash problem. I've had this backlash issue from day one; it sure seems like something that could have been taken car of by Celestron before the sent it out. Or maybe it's just an inherent problem with all goto GEMs.

Richard

#5 frito

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Posted 03 September 2013 - 09:30 AM

its a common issue with many commercial GEMs made in china.

If you buy a higher end mount like an AP, Tak, Losmandy etc. your less likely to see such an issue because they are all made to tighter tolerances and are far less mass produced, in fact many are made by small shops that take their time on them. but you get what you pay for.

it really is not a hard proceedure even for someone not very adept at mechanical things and the only tools you should need are screw drivers and a metric hex key set.

if you wish for someone to do the work for you then these folks can do it for you

http://www.deepspace...ron-advanced...

he lurks around here as well so perhaps you could contact them and see what they would charge just for a mesh adjustment if you don't want them to do the complete overhaul job on the mount.






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