Jump to content


Photo

Cleaning CG-5 ASGT internal gears

  • Please log in to reply
29 replies to this topic

#1 sneutrino

sneutrino

    Vostok 1

  • -----
  • Posts: 119
  • Joined: 08 Aug 2009
  • Loc: San Francisco, CA

Posted 06 August 2013 - 09:30 PM

My poor CG-5 sat through a dust storm and is making some small sandy crunching noises when I use the motors. Incidentally, there is no sand noise when I rotate the RA or DEC after loosening the black levers/locks and rotate those axes manually (without the motors/hand control).

At least as a first try, I just want to remove and clean the copper colored gears on the inside. My understanding is that I should apply a degreaser, then re-grease them with a synthetic grease. I'm not mechanically inclined so I have questions:
1) Is there a particular kind of 'degreaser' I should buy or is this just a generic product?
2) Is there a particular kind of (synthetic) grease I should buy?

Attached Files



#2 frito

frito

    Apollo

  • -----
  • Posts: 1183
  • Joined: 05 Oct 2012
  • Loc: Fremont, CA

Posted 06 August 2013 - 09:37 PM

yeah sounds like your worm gear is what is crunching, not good and if you used it that way you could have damaged the teeth, if you only use the mount for visual its probably not a big deal, for AP it could give you problems.

degreaser, use whatever, the point is to clean it. its metal as long as you use something normal and not say acid you won't hurt it.

for re-greasing, a typical lithum grease would work fine. if you want it to be as smooth as possible i believe many recommend superlube, but grease is grease, you want something that stays in place well but is not so thick that it causes unnessisary stiction etc.

#3 frito

frito

    Apollo

  • -----
  • Posts: 1183
  • Joined: 05 Oct 2012
  • Loc: Fremont, CA

Posted 06 August 2013 - 09:39 PM

ah now your picture works. that is the reduction gear that connects the motor (the motor has a gearbox on it as well) to the worm gear. the motor's gearboxes are pretty well sealed so you can leave them alone but the worm gears are not very well sealed, if its still crunching after cleaning that reduction gear set you need to tear the mount completely apart to get at the worm gear systems. if you go that far you might just want to look at getting a hypertune kit that will replace various teflon bearings etc.

#4 pogobbler

pogobbler

    Viking 1

  • -----
  • Posts: 527
  • Joined: 30 Sep 2008
  • Loc: Central Indiana, USA

Posted 07 August 2013 - 12:58 AM

I recently tore down, cleaned, degreased and re-lubed my ASGT mount. It wasn't really a hard job, just keep track of where the parts go and you shouldn't have a problem. You can easily find step by step instructions with photos to tear down this and similar mounts just by doing a quick search. I used mineral spirits to degrease all the parts and used Super Lube to relubricate everything and it works like a charm. I found it to work much better than the lithium grease I used on an older CG5 mount. In fact, I ended up cleaning up and regreasing the old mount after I did the ASGT. I hadn't used the mount in a while and the axes were very stiff-- not quite frozen, but it wouldn't have been useable like it was before I cleaned and regreased it. Now, with the Super Lube, it works great and I anticipate it lasting a lot longer then the lithium grease did.

#5 sneutrino

sneutrino

    Vostok 1

  • -----
  • Posts: 119
  • Joined: 08 Aug 2009
  • Loc: San Francisco, CA

Posted 07 August 2013 - 06:06 PM

One of the two black hex screws in that small copper gear appears to be totally stuck so I'm going to try to clean it in place.

Does anyone know how to remove the larger of those pictured gears? I removed two hex set screws from it but it is still stuck.

I messaged Michael Harrison about fixing the pictures on his blog post - http://dragonseye.co...ron-CG-5-mount/ - that may be useful.

#6 sneutrino

sneutrino

    Vostok 1

  • -----
  • Posts: 119
  • Joined: 08 Aug 2009
  • Loc: San Francisco, CA

Posted 07 August 2013 - 06:08 PM

I may have to clean and grease both of them 'in place'.

#7 frito

frito

    Apollo

  • -----
  • Posts: 1183
  • Joined: 05 Oct 2012
  • Loc: Fremont, CA

Posted 07 August 2013 - 07:57 PM

its a brass gear and yea there are two in each one. it is metric, make sure to use the correct size. do not use standard hex keys on metric it WILL result in stripping if you strip it you will need to either drill it out carefully (very as its a brass gear, its soft metal) or probably a better idea find a small easy out that will fit into the hole to remove it. if care is taken it will come out with the right tools and some elbow grease.

I recently had to remove some extremely torqued down 3mm and 4mm hex set screws on one of our machines at my work, the 3mm came out with some effort and a T handle hex wrench, the 4mm set screws on the thing were torqued so good i had to use a 4mm T handle with a very LAEGE channel lock used to turn the T handle while the part was held in a vice! I really though it was a bad idea but I was careful and both broke free with a snap and were good to go!

#8 sneutrino

sneutrino

    Vostok 1

  • -----
  • Posts: 119
  • Joined: 08 Aug 2009
  • Loc: San Francisco, CA

Posted 09 August 2013 - 03:42 PM

I ran the motors for less than 5 seconds so it should be pretty OK.

No idea how to get the brass gears off so I am leaving them on, but it is easy enough to take a lot of things apart and get to the worm gear so I cleaned those. Super lube multipurpose grease isn't arriving until Tuesday so I will update then.

#9 mclewis1

mclewis1

    Thread Killer

  • ****-
  • Posts: 11069
  • Joined: 25 Feb 2006
  • Loc: New Brunswick, Canada

Posted 09 August 2013 - 05:20 PM

So the accepted plan is ... careful dissassembly (paying particular attention to the thin spacers which are usually present, they are often overlooked because of being "glued" in place with the old lube), good cleaning to remove the existing lube and any dirt, and then only small amounts of new lube during re assembly. The worm gear adjustment is checked by manually moving it through the ring gear's entire travel.

#10 sneutrino

sneutrino

    Vostok 1

  • -----
  • Posts: 119
  • Joined: 08 Aug 2009
  • Loc: San Francisco, CA

Posted 12 August 2013 - 05:37 PM

The super lube arrived early and I finished the DEC section, but there is a point of concern. You know how the DEC should look like the 4th picture in this link http://astronomer.pr...ion=display&... ? For example, the metal ridge on the shaft that you can see in the DEC sections polar scope window, this ridge is centered in the window. When I put mine back together and lined up the two index marks, it is 10 to 15 degrees off. Is this a problem? It might be because I was rotating the DEC via the worm gear while it was partially assembled.

#11 RTLR 12

RTLR 12

    Aurora

  • *****
  • Posts: 4577
  • Joined: 04 Dec 2008
  • Loc: The Great Pacific NorthWest

Posted 12 August 2013 - 06:13 PM

There is nothing that you could have done that would have change the alignment marks. They are in the same place now as when you started. They are just an arbitrary starting position anyway. I removed the factory marks on my CG-5's and add my own marks in the proper locations.

Stan

#12 sneutrino

sneutrino

    Vostok 1

  • -----
  • Posts: 119
  • Joined: 08 Aug 2009
  • Loc: San Francisco, CA

Posted 12 August 2013 - 06:59 PM

I didn't move the marks, but I must have moved some mechanical axis away from the default position.

So the index marks are truly irrelevant if I'm going to do a Goto alignment procedure anyway? Good.

#13 RTLR 12

RTLR 12

    Aurora

  • *****
  • Posts: 4577
  • Joined: 04 Dec 2008
  • Loc: The Great Pacific NorthWest

Posted 12 August 2013 - 07:41 PM

They just give you a reference point to start your alignments from. I try to get the RA axis, using the CW bar, as vertical as possible and the dovetail parallel to the polar axis. Then I place my marks where I don't have to contort to see them. Then, because I use so many different scopes with my mounts, I just use them as a reference. They don't need to be exact.

Stan

#14 EFT

EFT

    Vendor - Deep Space Products

  • *****
  • Vendors
  • Posts: 2564
  • Joined: 07 May 2007
  • Loc: Phoenix, AZ

Posted 13 August 2013 - 10:10 AM

I didn't move the marks, but I must have moved some mechanical axis away from the default position.

So the index marks are truly irrelevant if I'm going to do a Goto alignment procedure anyway? Good.


Stan is correct. You probably never noticed the alignment of the hole before you dug into the mount. You will now notice things that you hadn't before since you are now more familiar with the mount. The marks are arbitrary, but it is most helpful if they are set so that the RA is vertical and the DEC is pointed straight forward because that is the general position that the mount assumes it is starting from. If you don't have the mount pointing that way to start, then the first alignment star will be further off, but after that it won't matter.

#15 obin robinson

obin robinson

    Mercury-Atlas

  • *****
  • Posts: 2667
  • Joined: 25 Oct 2012
  • Loc: League City, TX

Posted 13 August 2013 - 12:00 PM

1) Is there a particular kind of 'degreaser' I should buy or is this just a generic product?
2) Is there a particular kind of (synthetic) grease I should buy?


1) The best degreaser I've ever used is pure isopropyl alcohol mixed with distilled water. It works great with multi million dollar aircraft and it works great with telescope mounts.

2) The best grease I've ever used is Militec-1:
http://www.militec1.com/grease11.html

It works great in everything from automatic weapons in the desert to heavy equipment in sub zero temperatures. It works awesome for telescope mounts too. It's what I use on all mount tuning operations.

obin :cool:

#16 sneutrino

sneutrino

    Vostok 1

  • -----
  • Posts: 119
  • Joined: 08 Aug 2009
  • Loc: San Francisco, CA

Posted 13 August 2013 - 04:09 PM

The RA axis is very sticky when unlocked. What could be the problem?
- No motor or worm gear attached yet.
- Made no change (no cleaning) to the ring of bearings near the polar scope end except for adding a tiny amount of super lube.
- Tried with a moderate amount of grease on the teflon ring, and with very very little grease on teflon ring.
- Tried with both orientations of the bearing ring thing (see 9th picture at http://astronomer.pr...ion=display&... , the object with two concentric metal rings and black plastic between them). Everything on this item is rotating very smoothly though.

#17 RTLR 12

RTLR 12

    Aurora

  • *****
  • Posts: 4577
  • Joined: 04 Dec 2008
  • Loc: The Great Pacific NorthWest

Posted 13 August 2013 - 04:34 PM

Are you sure the clutch is not causing trouble? You may want to pull it apart and see where the interference is. Look for indications of gauldng. Are you just turning the shaft inside the ring gear or are you turning the ring gear and shaft together when it binds?

Stan

#18 sneutrino

sneutrino

    Vostok 1

  • -----
  • Posts: 119
  • Joined: 08 Aug 2009
  • Loc: San Francisco, CA

Posted 13 August 2013 - 05:46 PM

Ok, so I can prescribe any level of stickiness that I want by tightening that stack of rings on the bottom near the polar scope. I guess that it isn't supposed to be tightened all the way, since that binds everything. The rings ought to be a little loose, then locked down onto the axis by tightening the 3 small set screws that bite into the lower threaded part of the axis.

But, I can't get the RA lock knob to have any effect as I play with different tightness levels via rings...

#19 sneutrino

sneutrino

    Vostok 1

  • -----
  • Posts: 119
  • Joined: 08 Aug 2009
  • Loc: San Francisco, CA

Posted 13 August 2013 - 05:46 PM

Is the clutch the thing that the lock knob controls?

#20 sneutrino

sneutrino

    Vostok 1

  • -----
  • Posts: 119
  • Joined: 08 Aug 2009
  • Loc: San Francisco, CA

Posted 13 August 2013 - 06:32 PM

Oh, I get it now.

When the worm gear is in place, it holds onto the aluminum/geared part of the RA axis, which allows the two parts of the RA axis to move independently of each other when the lock knob is unlocked.

#21 RTLR 12

RTLR 12

    Aurora

  • *****
  • Posts: 4577
  • Joined: 04 Dec 2008
  • Loc: The Great Pacific NorthWest

Posted 13 August 2013 - 06:37 PM

:waytogo:.

#22 sneutrino

sneutrino

    Vostok 1

  • -----
  • Posts: 119
  • Joined: 08 Aug 2009
  • Loc: San Francisco, CA

Posted 13 August 2013 - 10:14 PM

Does anyone know what, if any, lubricant/grease is supposed to goes on the large aluminum cylinder (see 6th picture in http://astronomer.pr...ion=display&... ) ? I'm having trouble with this on the DEC axis. I never actually removed the one on the RA axis so I had no problem.

With super lube synthetic grease on it, it is difficult to put on, and very resistant to movement when it's on. This is still true but to a lesser extent when I remove most of the super lube from it.

I wonder if it's supposed to have no lube , or a different kind of lube.

I also have Super Lube Dri-Film lubricant which is a WD-40 like solution, I might try that, but am interested to know if anyone has insight on this...

edit: I might use regular WD-40, I am not so sure about this dri-film stuff, as it leaves a fine teflon powder which has some not so nice properties.

edit2: Certainly the geared part of the cylinder should have grease. I'm asking about the rest of it.

#23 EFT

EFT

    Vendor - Deep Space Products

  • *****
  • Vendors
  • Posts: 2564
  • Joined: 07 May 2007
  • Loc: Phoenix, AZ

Posted 13 August 2013 - 10:54 PM

Does anyone know what, if any, lubricant/grease is supposed to goes on the large aluminum cylinder (see 6th picture in http://astronomer.pr...ion=display&... ) ? I'm having trouble with this on the DEC axis. I never actually removed the one on the RA axis so I had no problem.

With super lube synthetic grease on it, it is difficult to put on, and very resistant to movement when it's on. This is still true but to a lesser extent when I remove most of the super lube from it.

I wonder if it's supposed to have no lube , or a different kind of lube.

I also have Super Lube Dri-Film lubricant which is a WD-40 like solution, I might try that, but am interested to know if anyone has insight on this...

edit: I might use regular WD-40, I am not so sure about this dri-film stuff, as it leaves a fine teflon powder which has some not so nice properties.

edit2: Certainly the geared part of the cylinder should have grease. I'm asking about the rest of it.


There are two problems here. First and foremost is the fit of the ring gear. The metal to metal surfaces on the gear and the axis casting must be sanded and polished to fit better and smoothly. Once that is done, then you can move on to lubing things and should use SuperLube for this. The Dri-Film might work if you already have it, but normal SuperLube all-purpose grease works just fine. The key is to use a very small amount. The best way to do that is to put some lube on the inside of the ring gear, slide it into place and turn it around a bit, then remove the gear and wipe the inside surface of the gear off. When you replace the gear again, as long as you didn't use too much lube in the first place, the remaining thin coating of lube is all you will need.

If you are having problems either getting things back together or having them be too stiff to turn, then there is a good chance you are not doing these things correctly. In addition, The metal to metal surface between the axis casting and the axis housing must be treated the same way. They need to be sanded a bit and polished and then a very thin coating of lube applied.

The DEC axis of the CG-5 is consistently one of the most difficult things that I tune up. There are so many metal to metal contact surfaces and no bearings that it is a constant struggle to get things moving and they rarely end up moving as freely as I would like. All the contact surfaces must be properly fit and move easily before any lube is applied and then after the lube it applied (even a thin layer) you may find that you need to go back and do more work.

#24 sneutrino

sneutrino

    Vostok 1

  • -----
  • Posts: 119
  • Joined: 08 Aug 2009
  • Loc: San Francisco, CA

Posted 13 August 2013 - 11:41 PM

I want to sand and polish it since it got nearly stuck twice with super lube grease, and then with the dri-film, which was stressful.

Should I use a silicon carbide sandpaper at 600 grit, then move to 1000 and 2500 grit?
http://home.howstuff...l-sandpaper.htm

#25 EFT

EFT

    Vendor - Deep Space Products

  • *****
  • Vendors
  • Posts: 2564
  • Joined: 07 May 2007
  • Loc: Phoenix, AZ

Posted 13 August 2013 - 11:47 PM

I want to sand and polish it since it got nearly stuck twice with super lube grease, and then with the dri-film, which was stressful.

Should I use a silicon carbide sandpaper at 600 grit, then move to 1000 and 2500 grit?
http://home.howstuff...l-sandpaper.htm


That's a good plan. You can even start with 400 but you probably don't need to go further than 1000 or 1200. Finish up with some aluminum polish when you are done sanding.






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics