Scary Task Ahead

[pbyrne]

Hi there

I recently purchased an 8" Newtonian on a CG-5 mount with a RA drive for a ridiculously low price, the scope is fine, the mount is another matter. The tripod legs won't extend and the motor won't drive the RA axis, the motor does work.

I managed to fix the legs, but I have decided to strip down the EQ head and clean it out, I believe that the problem is the treacle the manufacturers use for grease:icon_rolleyes:, I logged onto astronomyboy.com for detailed instructions.

I admit that this is a task that fills me with a little trepidation as I am not the most mechanically minded person on the planet and the fear of losing some of the plastic washers is real.

I'm going to devote my Saturday to the job, unless the wife has other plans for me.

I'd like everyone to keep their fingers crossed for me and I'll report on how I got on.

Paul

[Psychobilly]

Dissasemble the mechanism inside a bowl or baby bath or over a towel that way small bits don't disappear...

Billy...

[beamish]

Follow all the steps, keep a list handy if you think that will help and tick off as you go along. Make sure you have ALL the tools etc you're likely to need.

Ensure you have no interruptions and not too much coffee

Best o' luck, Karlo

[Jarndyce]

If you have a digital camera, it's useful for keeping track of exactly how things looked before you took them apart...

[pbyrne]

I had thought about using the camera and I think I'll go with that, making sure I don't get grease all over it of course.

No distractions Beamish? Throw the wife and kids out the door and lock it, will that work?

Paul

[beamish]

YUP ! Exactly what you don't need is the kids pestering you for something at a critical point

[merlinxlm]

I think that this link will interest you, it describes in detail the whole procedure. http://www.astronomyboy.com/cg5/

[philsail1]

Good luck with the job Paul!

Another tip is to have some jam jar lids, or margerine tubs to put the different sized screws/bolts etc in. Label the lids or tubs with where the screws etc come from.

Regards,

philsail1

[pbyrne]

Well, I got aorund to doing the job today and it was an unqualified 50% success. Following the instructions posted on Astronomyboy.com I separated the mount into the dec. and RA axis and began to work on the dec. axis. The stuff inside wasn't grease, it was thick and yellow, ever see a baby with a bad cold? I managed to separate the dec shaft from the housing and spent the next hour removing the disgusting goo, I used Holt's multi spray, it acts as a degreaser and ripped it off nicely. Applying lithium grease I reassembled the unit, tested the movement, beautiful.

Then I moved onto the RA axis, and now the trouble arose. I tried to remove the ring nut that would allow me to separate the RA shaft from the housing to clean it, and it wouldn't budge. No matter what I tried the thing remained stubbornly in place. I applied some of the degreaser, thinking it might loosen it, no joy, I got rhe wife's hairdryer and heated up the ring nut, hoping that it might melt the grease, again, no luck. I spent the best part of an hour trying to free it with no success. :BangHead:I suspect that maybe the ring nut was threaded on incorrectly and jammed it, there's nothing else I can think off.

Because I was unable to gain access to the worm gear to clean the teeth I attempted something else. Again I used the hairdryer and heated the area around the casing next to the worm gear, then I applied degreaser through the small gap in the housing. I rotated the RA back and forth vigourously to work the degreaser in, it wasn't going to clean the teeth too much, but it might loosen some of the glup. When I was satisfied I squirted some lithium grease through the same gap and rotated the unit again to work it in. The RA axis was a little looser, but not much and I confess myself semi pleased.

I was a little tremelous about the task, but when I completed the dec. axis smmothly my confidence grew, a stuck ring nut prevented me from completing the task:angry:, but, that's life.

If anyone else is considering dismantling their CG-5 and is feeling a little aprehensive, don't, the instructions printed by astronomyboy are clear cut and easy to follow, so give it a go.

Paul

[philsail1]

Paul,

Excuse me saying this but did you know that the "ring" at end of RA shaft is "locked" to shaft by three very small "allen" headed bolts. You need to slacked them off before the ring nut will screw off. The "Asronomy Boy" site shows you on the "CG5" stripdown part.

I apologise if you already knew this.

REgards,

philsail1

[pbyrne]

The small screws weren't the problem as they were loosened.

I managed to get to the RA gear shaft when I removed the RA worm, I cleaned it as best I could, not as well as I would like, but the majority of the glue was removed and new grease applied.

If you've never seen this stuff it's unbelievable, it's thick and lumpy and awful. I'm only guessing that it's cheap to manufacture.

Paul