CLOUDY NIGHTS FORUM ARCHIVES
"Live Forums" can be found here: Live Forums


Equipment Discussions >> Mounts

Pages: 1
Craig Levine
member


Reged: 04/12/09
Posts: 10
SVP RA Clutch Problem: Won't stay Engaged
      #3124361 - 05/24/09 12:09 PM

Hi all,

For the moment I mount an AP 102 on an Orion SVP. Until I can get a Celestron CGEM, this is what I have to work with. The RA motor seems to have a problem with the clutch. I tighten it to engage the gears for tracking and slewing, but instead of staying tight to the gears, it loosens fairly quickly allowing for only a couple of minutes of tracking and a few seconds of slewing. Does anyone have any suggestions for fixing this?

Cheers,

- Craig


Post Extras: Print Post   Remind Me!   Notify Moderator  
Graystar
super member


Reged: 04/19/09
Posts: 119
Loc: Brooklyn, NY
Re: SVP RA Clutch Problem: Won't stay Engaged new [Re: Craig Levine]
      #3124427 - 05/24/09 12:43 PM

I don't have that problem with mine. All I can suggest is that your meshing is too tight.

loosen the RA motor and place a piece of paper between the two gears. Make sure the paper is on the light side, like 20 lbs (typical copy paper.)

Mesh the gears tightly with the paper in between and tighten the RA motor in place. Now operate the RA motor to remove the paper. That should give you ideal meshing.

I also found it helpful to apply a tiny dab of grease to the end of the threads of the RA motor mounting screw (that long screw that comes from behind the mount.) Also, I like to apply a dry lube (grease works too) to the head of that screw (the part that contacts the metal of the mount.) Since there's no washer, I find this helps keep things tight.

--------------------
Warning! I'm a newbie...I don't know anything!


Post Extras: Print Post   Remind Me!   Notify Moderator  
hudson_yak
Carpal Tunnel


Reged: 11/15/07
Posts: 1548
Loc: Hyde Park, NY, USA
Re: SVP RA Clutch Problem: Won't stay Engaged new [Re: Graystar]
      #3124467 - 05/24/09 01:04 PM

I would agree, there must be too much force required to turn the gearing, possibly the worm gear. For northern hemisphere users the clutch will unscrew if the effort is high.

Another possibility, does the clutch still have the rubber ring in between it and the drive gear? And no stray grease in that location?

Mike

--------------------
Tele Vue-85 + Quarter Hitch + Berlebach UNI 24
Meade 12" LightBridge
Orion ED100 + Losmandy GM-8
Orion SVP
Meade 8" LX10


Post Extras: Print Post   Remind Me!   Notify Moderator  
Craig Levine
member


Reged: 04/12/09
Posts: 10
Re: SVP RA Clutch Problem: Won't stay Engaged new [Re: hudson_yak]
      #3124483 - 05/24/09 01:15 PM

Quote:

I would agree, there must be too much force required to turn the gearing, possibly the worm gear. For northern hemisphere users the clutch will unscrew if the effort is high.

Another possibility, does the clutch still have the rubber ring in between it and the drive gear? And no stray grease in that location?

Mike




Thanks for the replies, guys.

Hmmmm. No rubber grip ring in either RA or DEC. I'll clean the clutch to see if that helps. Not much force is required to turn the gears. A light touch is all that's needed to move them manually. I'll give that go to see what happens and then if it doesn't work I'll try Graystar's suggestion. I'll have to re-read it to make sure that I understand it correctly.

Cheers,

- Craig


Post Extras: Print Post   Remind Me!   Notify Moderator  
Craig Levine
member


Reged: 04/12/09
Posts: 10
Re: SVP RA Clutch Problem: Won't stay Engaged new [Re: Craig Levine]
      #3124509 - 05/24/09 01:27 PM

I've also just noticed an issue in the DEC axis with the gears turning but the axis not rotating (hand knobs stop spinning, no motion visible on scope) at a certain point in the rotation. Odd.

- Craig


Post Extras: Print Post   Remind Me!   Notify Moderator  
Graystar
super member


Reged: 04/19/09
Posts: 119
Loc: Brooklyn, NY
Re: SVP RA Clutch Problem: Won't stay Engaged new [Re: Craig Levine]
      #3124661 - 05/24/09 03:02 PM

My clutches don’t have rubber grips either, and I think I have the latest design because my DEC motor has the jack within the motor can, at the rear of the can. The older design has the jack on its own little bracket (which everyone complained about because it's easy to knock into it.)

I’d suggest cleaning the brass parts with a solvent to ensure there’s no grease or oil on them. When you reassemble, you can place a small amount of grease (I prefer dry lube) on the brass threads that the chrome lock nut screws onto, and on the face of the chrome nut that presses against the brass gear. That will help get the lock nut tighter.


On your DEC...
If the hand knobs stop spinning (I’m presuming a knob on each side) then the worm gear isn’t turning. If the worm gear isn’t turning, then the clutch gear must be slipping. This has to be the case, because one of your knobs is attached to the clutch assembly. If the entire clutch assembly were slipping, then you’d see one knob turning while the other knob stays put.

It may be that at that particular point there is so much pressure needed to rotate the worm, that the motor just unscrews the chrome lock nut instead. So something needs to be adjusted. Here’s a question...when it stops turning is the motor position 180 degrees from the axis release?

I recently noticed that on my SVP, the DEC motion control is harder to turn if I tighten the DEC axis release more than I need to. So I can see how it’s possible to increase the force needed to turn the worm.

Personally, I’m not crazy about the axis release system. If there’s any play at all between the worm ring and the DEC or RA axle, the worm won’t be centered when you lock the axle release. This will cause binding and will increase the pressure needed to turn the motion control knob on the opposite end of the axis release.

--------------------
Warning! I'm a newbie...I don't know anything!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Craig Levine
member


Reged: 04/12/09
Posts: 10
Re: SVP RA Clutch Problem: Won't stay Engaged new [Re: Graystar]
      #3124664 - 05/24/09 03:10 PM

Thanks Graystar,

I'll stop in to the local hardware store tomorrow and pick up some dry lube. I agree with you on the axis release system. It's not the greatest. Meantime, I'll clean the brass parts this afternoon.

Cheers,

- Craig


Post Extras: Print Post   Remind Me!   Notify Moderator  
hudson_yak
Carpal Tunnel


Reged: 11/15/07
Posts: 1548
Loc: Hyde Park, NY, USA
Re: SVP RA Clutch Problem: Won't stay Engaged new [Re: Craig Levine]
      #3125462 - 05/25/09 12:11 AM

I only bought my SVP about a year and a half ago, so your clutch has no rubber ring for the back side of the gear to grip against the clutch body? If mine didn't have that it would be unscrewing a lot more easily I'd think. Seems like an odd change for them to make. Perhaps you can get an o-ring to work.

That's a good point about the binding caused by the axis lock, hadn't ever considered it. I have always had quite a lot of backlash adjusted into my worm engagements to avoid any binding, and it also has seemed different in different parts of the rotation. Guess that must be why.

Mike

--------------------
Tele Vue-85 + Quarter Hitch + Berlebach UNI 24
Meade 12" LightBridge
Orion ED100 + Losmandy GM-8
Orion SVP
Meade 8" LX10


Post Extras: Print Post   Remind Me!   Notify Moderator  
Graystar
super member


Reged: 04/19/09
Posts: 119
Loc: Brooklyn, NY
Re: SVP RA Clutch Problem: Won't stay Engaged new [Re: hudson_yak]
      #3125974 - 05/25/09 10:16 AM

EDIT - Yes, I have rubber rings on the side opposite the clutch lock nut. The clutch locknut itself does not have a rubber ring, although it looks like there's space for one.

I'm lucky that my worm gear engagement on my RA axis appears to be unaffected by the amount of pressure on the release. I adjusted the engagement to be just a hair on the tight side, so the feel changes from "perfect" to "slight binding" over the course of 360 degrees, and the motor doesn't seem to have a problem with it.

The DEC axis is bad, though. I haven't taken it apart yet but this discussion has me thinking about it again. The pressure needed to turn the motion control depends heavily on how tight the release is. I need to find a way to fix that.

--------------------
Warning! I'm a newbie...I don't know anything!


Edited by Graystar (05/25/09 10:26 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Craig Levine
member


Reged: 04/12/09
Posts: 10
Re: SVP RA Clutch Problem: Won't stay Engaged new [Re: Graystar]
      #3126986 - 05/25/09 08:02 PM

I think I found the solution!

I was digging around in my workshop and I found a rubber washer that was just about the right size. I enlarged the hole with an exacto knife and everything seems to be holding snugly. I'm going to do some slewing and let the the motor run for a few hours to see how things work, but a five minute slewing test had it moving along nicely. Thanks for the suggestions everyone!

Cheers,

- Craig


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1


Extra information
1 registered and 124 anonymous users are browsing this forum.

Moderator:  Charlie Hein, lineman_16735 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 338

Jump to

CN Forums Home



Cloudy Nights Sponsor: Astronomics