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#1 erminigilde

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Posted 03 December 2012 - 06:19 PM

Any ideas why my lx200ACE sticks and grabs at the beginning of its movement in dec.I`ve noticed it only occurs at colder temps 32f or less.Ive cleaned and regreased the the ring and worm gears with Pete`s red grease.Called Meade and all they said was send it back.Ìt`s outside in the observatory where I set up a heat lamp and sure enough when warmed up no problem.The noise reminds me of anti-lock brakes. thanks Walt in Québec

#2 Christopher Erickson

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Posted 03 December 2012 - 07:59 PM

It is called stiction and can be common in mounts with spring-loaded worm blocks.

It is when the worm gear spiral teeth ride up on one side of the worm wheel tooth grooves and suddenly pop back down to the bottom of the grooves when it hits the range-of-motion limits set in the spring loading mechanism. This process repeats rapidly and creates a chattering sound.

I doubt that Meade understands cold temperature issues with their spring-loaded worm drives on the LX200 scopes well enough to properly deal with it.

Replacing the worm drive tension-spring with a slightly-stronger spring and then adjusting the worm block spring range-of-play down to a minimum will help, as will making sure that the OTA is fairly-balanced in DEC motion.

This problem can also manifest in the RA worm drive and has the same solution.

If the problem still exists to some point after these adjustments then I would suggest removing ALL traces of the current grease and replace with a 3:1 blend of Lubriplate-105 and Nye Fluorocarbon Gel 868H damping grease. This is very similar to the type of grease formula used by Astro-Physics in their mounts. The Lubriplate-105 gives smooth tracking over a very-wide temperature range and the 868H damping grease is for smooth slewing without stiction and chattering.

I hope this helps.

#3 nitegeezer

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Posted 03 December 2012 - 08:06 PM

When it is cold, with the power off and the dec clutch tight, can you feel anything sticking with the manual dec knob? If I remember correctly, the knob turns the motor, so this would help determine a mechanical problem versus an electrical one.

It looks like Chris answered while I was typing, he has helped many here before, and welcome to CN.

#4 erminigilde

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Posted 04 December 2012 - 11:39 AM

Hi Chris: Thanks for the quick reply.I had a look at the dec ensemble and found the parts you mentioned.Before I replaced the spring I tried adjusting it in and out w/o any results.Cleaned the gears and tried lithium grease jsut to see.Same result.Tried to manually vary spring pressure by jiggling block.Niet.By now it,s +10 deg C and it runs fine.So much for short cuts.This is my 5th Meade sct but the first time I`ve had this problem.nOne question though:where does one get these exotic greases you suggested´.You`re in Hawaii.I feel you`re pain LOL.Walter in the middle of a heat wave.

#5 davebl

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Posted 04 December 2012 - 12:58 PM

Buck's scope tune up addresses the worm block spring as well as it's adjustment. Here's a link for 12" and under scopes.

http://www.petersone...buckstuneup.htm

There's also a study of this product as well as the Buck's gears.

http://www.petersone...ngham_study.htm

It might be worth looking into. I've installed both on my older 14" LX200 GPS and my scope runs great. Good Luck,

Dave

#6 Christopher Erickson

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Posted 04 December 2012 - 01:48 PM

Hi Chris: Thanks for the quick reply.I had a look at the dec ensemble and found the parts you mentioned.Before I replaced the spring I tried adjusting it in and out w/o any results.Cleaned the gears and tried lithium grease jsut to see.Same result.Tried to manually vary spring pressure by jiggling block.Niet.By now it,s +10 deg C and it runs fine.So much for short cuts.This is my 5th Meade sct but the first time I`ve had this problem.nOne question though:where does one get these exotic greases you suggested´.You`re in Hawaii.I feel you`re pain LOL.Walter in the middle of a heat wave.


White Lithium grease is quite possibly one of the worst greases you can use in a worm drive and usually makes stiction worse instead of better. White Lithium should only ever be considered as an absolute last resort if you have to regularly work around or below -40 C/F. White Lithium also can do bad things if mixed with other greases. It can break down into corrosive compounds that can eat metals and metaloids, like aluminum. So if you choose to try White Lithium, you would be well-ahead to use an ultrasonic cleaner to get every last speck of the old greases out of the components.

Lubriplate-105 is fairly-common and can be found in a number of automotive supply stores as an engine assembly grease and comes in small tubes as well as five gallon buckets.

https://wbcindustria...-assembly-gr...

Nye Fluorocabon Gel 868H is harder to come by and is the more expensive of the two greases.

http://www.newgateon...0gram-tube.html

I hope this helps.

#7 erminigilde

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Posted 04 December 2012 - 07:43 PM

Thanks for the tip.Went out and immediately removed lithium and replaced with Petes red grease until the next step.I might ship it to khans scope in TO. Really appreciate all nthe help from you and others on site. Walter

#8 erminigilde

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Posted 05 December 2012 - 03:08 PM

Just tried exerting some hand pressure on the OTA while slewing in dec and the movement became smooth.A stronger spring might just be the solution,as Chris has suggested.






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