Out of all the parts of the RA axis what is the most susceptible to binding when it gets cold?

[Trippelforge]

I posted about my issues awhile back and since have been getting extremely frustrated. As well as straight depressed as my son gets let down each time we try and shoot. 

I have a lackluster  CG-4. However I have always been happy enough with it, and never ran into any cold weather issues until this year. I will fully setup outside, test the drive system out, as well as how tight it is to turn via 2 fingers. It's buttery smooth and I always think we are ready to go. When I got back outside an hour later or so it's very tight and it takes a lot of effort to turn. I tried adjusting the worm gear (several times) at that point without luck. Once I take it back inside about 30 minutes later it seems to "un stick" (small pop feeling) and go back to normal again. 

I thought maybe then it was the RA axis itself, so I ended up loosening that a bit, and I tried it again last night... same thing, it was very hard to turn. 

Since I have done this a half dozen nights now (and sometimes it happens mid session), so I am pretty sure the drop in temperatures is causing it. So my main question is out of all of the parts which one is doing this? I have taken apart the worm, cleaned it, checked for any play side to side (none). Tried varying levels of recommended grease (told here what to use), AND spent probably a few hours tweaking the worm housing. No luck obviously. 

Any ideas? I think I will be able to use it when it doesn't drop so cold, but between Nov - March it's ALWAYS cold at night here. Not to mention the summers are horrible... mosquitoes, high humidity, burning temperatures etc. And ya I know... I need to get something else... but it's not in the budget, I would love to figure this out.

Thanks!

[Peter Drew]

Vixen Super Polaris and GP mounts are prone to this as they rotate on plain bearings which require a stiff grease for load bearing.  This of course increases stiffness as the grease gets colder.  I think the CG4 is a clone of the Vixen mounts and may have a similar issue.    🙂

Edited March 15, 2023 by Peter Drew

[ONIKKINEN]

Have you completely disassembled the mount yet? I mean completely taken apart and not just the worm and its carrier. Should give some better insight as to what is binding.

[Trippelforge]

22 hours ago, ONIKKINEN said:

Have you completely disassembled the mount yet? I mean completely taken apart and not just the worm and its carrier. Should give some better insight as to what is binding.

I have not, but obviously at that point now. What will be tough is finding out what actually is binding since it won't be freezing. So I don't really know what to look for, although I guess a tear down and rebuild isn't going to hurt. This has been a huge PITA, and as mentioned I had no issues in the past and it doesn't have a lot of hours on it. 

 

[Clarkey]

6 minutes ago, Trippelforge said:

What will be tough is finding out what actually is binding since it won't be freezing

I assume this problem is occurring when it is below freezing? I have found with my mounts (specifically the HEQ5) that occasionally one of axis sticks slightly. I am pretty sure it is because the metal surfaces are very close together and a bit of condensation has got in and frozen. Normally I can just release the clutch and free it by hand - it then works fine. If yours rotates by hand with the clutch off, but still has the problem - the disassembly option may be your only choice.

[ONIKKINEN]

1 hour ago, Trippelforge said:

I have not, but obviously at that point now. What will be tough is finding out what actually is binding since it won't be freezing. So I don't really know what to look for, although I guess a tear down and rebuild isn't going to hurt. This has been a huge PITA, and as mentioned I had no issues in the past and it doesn't have a lot of hours on it. 

 

There could be obvious rust/water damage somewhere in the innards or the lubricant could have thinned out and mixed with water from the outside which would freeze at night. Hard to say by just guessing, youll know more when the mount is in pieces.

[Trippelforge]

3 hours ago, Clarkey said:

I assume this problem is occurring when it is below freezing? I have found with my mounts (specifically the HEQ5) that occasionally one of axis sticks slightly. I am pretty sure it is because the metal surfaces are very close together and a bit of condensation has got in and frozen. Normally I can just release the clutch and free it by hand - it then works fine. If yours rotates by hand with the clutch off, but still has the problem - the disassembly option may be your only choice.

 

At first it was once temps dropped down to around -2'C. I knew if it was going to go that low it was pointless. Now it's seems to be doing it even above freezing, I think the other night it was around 3'C. The last session I actually was able to use the mount it was around 9'C. I actually tried to keep the worm gear housing warm one of the nights with glove warmers taped to it (lol). But they didn't get hot enough to do much.

I can rotate it by hand when it's unlocked. Once locked down it's noticeably hard to turn the axis, even with a knob connected. Ya I think it's becoming obviously I am going to have to do a tear down / re-build now. I have ran out of ideas, and frustrated as hell. 

[Peter Drew]

If it has been metal to metal binding there should be some witness marks on the mating surfaces.    🙂

[mikeDnight]

On 16/03/2023 at 18:02, Trippelforge said:

 

At first it was once temps dropped down to around -2'C. I knew if it was going to go that low it was pointless. Now it's seems to be doing it even above freezing, I think the other night it was around 3'C. The last session I actually was able to use the mount it was around 9'C. I actually tried to keep the worm gear housing warm one of the nights with glove warmers taped to it (lol). But they didn't get hot enough to do much.

I can rotate it by hand when it's unlocked. Once locked down it's noticeably hard to turn the axis, even with a knob connected. Ya I think it's becoming obviously I am going to have to do a tear down / re-build now. I have ran out of ideas, and frustrated as hell. 

 If the RA moves freely when unlocked, I'd suspect it's the worm pressing too tightly against the gear wheel. You can adjust the contact pressure by loosening the grub screws, or by turning the brass bearing slightly through which the worm rod passes to disengage it a little. Too much and you'll get backlash, so it may need a little trial and error, but I doubt you'll need to dismantle the mount.

[jock1958]

And once you’ve sorted any issues with the mechanicals think about re-assembling with a grease that works well in low temperatures.
My Skytee 2 Alt Az mount was originally lubed with that horrible Synta glue which was useless in the cold, since then I’ve stripped it down and used standard grease for wheel bearings which works nicely, next strip down I’ll be using Aeroshell green grease 33 as used in aircraft undercarriage and flying control systems, at 40,000 ft outside temp is approx -50°.