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Greasing a classic C8 mount

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7 replies to this topic

#1 ANM

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Posted 18 October 2020 - 01:16 PM

I have another question regarding a C8 classic mount: do the clutch and brake surfaces get greased? It is metal on metal so I thought yes but it will mean that higher pressure is needed for the clutch and brake to work. But without grease it's metal on metal (or nylon on metal). In later C8s there are the three hex-head nylon bolts that press on the side of the aluminum worm wheel, this I think should be greased since the worm wheel rotates (even though it's slow) and the nylon bolts are stationary. But what about the RA lock lever's nylon pad?

 

One mount I have been working on had everything that rubbed on anything else greased, is that really necessary?


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#2 Photo-Dave

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Posted 18 October 2020 - 01:46 PM

I have 2 late 70’s C8’s. The one I’m using now doesn’t always track the object when I lock the slow motion adjustment wheel. So I’ll be following this thread, hoping to learn the finer points of use & maintenance of the dual motor clock drive. When I lock mine in it will sometimes drift in the other direction. Then I’ll turn the knob slightly and it will start tracking correctly. It’s very frustrating, especially when I’m trying to capture a planet on video.

#3 Photo-Dave

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Posted 18 October 2020 - 01:46 PM

I have 2 late 70’s C8’s. The one I’m using now doesn’t always track the object when I lock the slow motion adjustment wheel. So I’ll be following this thread, hoping to learn the finer points of use & maintenance of the dual motor clock drive. When I lock mine in it will sometimes drift in the other direction. Then I’ll turn the knob slightly and it will start tracking correctly. It’s very frustrating, especially when I’m trying to capture a planet on video.

#4 davidmcgo

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Posted 18 October 2020 - 02:43 PM

I would not grease the pressure plate or mating surface of the slow motion gear.  Loosen the clamp completely for large slews but some drag when fine tuning is OK.

 

Dave


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#5 ANM

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Posted 18 October 2020 - 05:27 PM

I have 2 late 70’s C8’s. The one I’m using now doesn’t always track the object when I lock the slow motion adjustment wheel. So I’ll be following this thread, hoping to learn the finer points of use & maintenance of the dual motor clock drive. When I lock mine in it will sometimes drift in the other direction. Then I’ll turn the knob slightly and it will start tracking correctly. It’s very frustrating, especially when I’m trying to capture a planet on video.

Are you sure you don't need to adjust the RA locking lever? With it locked it should track,

 

P.S. the default state, and you shouldn't be able to rotate the mount in RA by hand.


Edited by ANM, 18 October 2020 - 06:31 PM.


#6 Photo-Dave

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Posted Today, 02:01 AM

Are you sure you don't need to adjust the RA locking lever? With it locked it should track,

P.S. the default state, and you shouldn't be able to rotate the mount in RA by hand.


Sorry for the long delay in getting back to you. Thank you for your reply. Could you please explain a bit more on how I can adjust the RA Locking Lever? When it is locked should I be able to rotate the Mount by turning the RA control knob? Thanks again. I look forward to your answer. Dave

#7 Photo-Dave

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Posted Today, 02:12 AM

I have another question regarding a C8 classic mount: do the clutch and brake surfaces get greased? It is metal on metal so I thought yes but it will mean that higher pressure is needed for the clutch and brake to work. But without grease it's metal on metal (or nylon on metal). In later C8s there are the three hex-head nylon bolts that press on the side of the aluminum worm wheel, this I think should be greased since the worm wheel rotates (even though it's slow) and the nylon bolts are stationary. But what about the RA lock lever's nylon pad?

One mount I have been working on had everything that rubbed on anything else greased, is that really necessary?


How do I disassemble the mount to get to this area of the Clutch & Brake? I have 2 early orange tube C8’s that I need to service to track as best as they can for their age. Thanks again, Dave in PA.

#8 ANM

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Posted Today, 08:57 AM

Sorry for the long delay in getting back to you. Thank you for your reply. Could you please explain a bit more on how I can adjust the RA Locking Lever? When it is locked should I be able to rotate the Mount by turning the RA control knob? Thanks again. I look forward to your answer. Dave

Do not use the RA knob to try and force the mount to rotate in RA, you can strip the teeth on the gear.

 

When you are tracking the lever should be turned to the left (locked). To turn to a different celestial object first release the lock, then rotate to the object and lock it again.

 

When the RA is locked: if you can put moderate pressure (not excessive, you're not trying to break it!) on the OTA and turn it either the RA lever is not locked or the lever needs to be adjusted. If the lever needs adjusting:

  1. unlock  the RA lock, loosen the Allen set screw that is normally hidden (don't take the set screws out, just 1 or 2 turns)
  2. turn the lever to lock it
  3. loosen the second set screw (the one you can get to when it is locked) so the lever is free
  4. rotate the lever slightly to the unlocked position
  5. tighten the set screw
  6. test it again and repeat as necessary
  7. tighten the other set screw

When you hang cameras and 2" accessories on the back of the C8 the balance can be thrown off making the RA lock less effective, it will also make it more difficult slewing to an object. If it's out of balance, you may need balance weights, either Celestron's (sometimes available in the classifieds on CN), or some third party system.


Edited by ANM, Today, 09:01 AM.

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