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What damage can cold weather do to mounts?


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I have a lightly used (purchased new) CG-4. I lost tracking capability after the temperature went from 3'c to -7c  which seeming caused the worm gear to tighten up. I ended up taking it out and cleaning it, plus re-lubed prior to re-assembly. I also cleaned the internal main gear and lubed that as well. I then tweaked it until it moved freely but yet lacked any play. But now I cannot track... max amount of exposure time I can get is 15 seconds, prior I was getting 1 1/2 minutes. I tried two motor systems (old Celestron / new go-to), as well as a perfect polar scope alignment. Nothing helped.

Any idea on why this situation completely shut down tracking capability? Is there something I am missing in regards to re-installing the worm gear? It's been really frustrating, and yes I know the CG-4 is far from an optimal mount for AP. But up until now it worked great and still is in pretty new condition.  

Thanks for any tips / help!

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When you regreased the RA main gear teeth, did you grease all the way up to the top? If yes then the axis lock could be slipping. The top area of the RA gear should be left dry to create friction for the Teflon pad at the base of the axis lock. Just a thought.

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1 hour ago, Franklin said:

When you regreased the RA main gear teeth, did you grease all the way up to the top? If yes then the axis lock could be slipping. The top area of the RA gear should be left dry to create friction for the Teflon pad at the base of the axis lock. Just a thought.

Maybe I am confused on what the main gear is. It was the one that the worm gear rides on. I only mention it because I don't understand what "all the way up" means. As the only thing I could see were the teeth, so I lightly applied grease all the way around them. I did notice when I first opened it that there were globs of factory grease randomly. I tried to clean all that off though.

 

32 minutes ago, newbie alert said:

You may need to compromise abit of backlash on your gear mesh, having them too tight can lock the axis up...just one of the many things to stop it from performing 

Would that simply be done with raising the worm housing a bit using the set screw? I did do that a bit until it seemed to turn OK. But I am not sure how tight it still is, or well how loose it can be. I do notice when I turn the axis there is lag between each direction before it starts moving. Is that what is considered backlash in this case?

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2 minutes ago, Trippelforge said:

I did notice when I first opened it

Opened it, as in removed the worm to access the gear teeth? or opened it, as in completely taken the RA axis apart, to clean and regrease the whole shaft and bearings?

From what you've mentioned above, it sounds like you only took the worm off to regrease the teeth on the RA gear, so your problem must be related to the mesh of the worm with the gear. Re-setting this can be quite a frustrating task, very small adjustments make a big difference. The first time I attempted this with an old CG5 it took me hours of trial and error to get it right.

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The mount needs a little bit of backlash to move freely, no way to adjust it to be tight and not effect binding. For the RA axis its not an issue anyway since the gear should be constantly under load when tracking (so no backlash).

That said, which type of grease did you use and how much? You can have too much, there should be just enough to lubricate moving parts but not more than that. For the type you want to use some kind of white PTFE type grease that doesnt get sticky in the cold. Most "regular" type greases are more or less useless in sub zero conditions unless advertised otherwise.

By the way are you guiding? Unguided 90s sounds like a fantasy, 15s sounds much more reasonable.

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1 hour ago, Franklin said:

Opened it, as in removed the worm to access the gear teeth? or opened it, as in completely taken the RA axis apart, to clean and regrease the whole shaft and bearings?

From what you've mentioned above, it sounds like you only took the worm off to regrease the teeth on the RA gear, so your problem must be related to the mesh of the worm with the gear. Re-setting this can be quite a frustrating task, very small adjustments make a big difference. The first time I attempted this with an old CG5 it took me hours of trial and error to get it right.

Ya I took the housing to the worm gear off which also exposed the main axis gear. I cleaned the grease off of the worm gear, and most of the gunk on the main gear. Then lightly applied new grease, put it all back together and started tweaking it. I got it to where it felt smooth and fairly easy to turn (via set screw adjustment), then tightened everything back down snug. 

Considering I did this in 20 minutes total, I am obviously missing something. How did you test it while making the fine adjustments? I am going to assume just twisting the knob isn't accurate enough. Since I am going to obviously have to revisit this, any guidance on what I am looking for as an end result?

 

20 minutes ago, ONIKKINEN said:

The mount needs a little bit of backlash to move freely, no way to adjust it to be tight and not effect binding. For the RA axis its not an issue anyway since the gear should be constantly under load when tracking (so no backlash).

That said, which type of grease did you use and how much? You can have too much, there should be just enough to lubricate moving parts but not more than that. For the type you want to use some kind of white PTFE type grease that doesnt get sticky in the cold. Most "regular" type greases are more or less useless in sub zero conditions unless advertised otherwise.

By the way are you guiding? Unguided 90s sounds like a fantasy, 15s sounds much more reasonable.

 

The backlash on the RA axis is weird. For instance I can turn the worm gear and advance the mount. When I stop I can rotate the axis slightly with my hands. I can rinse and repeat that process forever, however I "think" it gets harder to move when I fully crank down on the clutch lever. Each time I do it though it bottoms out on something, such as I can't just freely spin the axis around. We are talking like 8mm in movement. There is also "lag" during movement of the worm gear when I change direction, perhaps that is the backlash and the other is something loose?

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1 hour ago, Trippelforge said:

Maybe I am confused on what the main gear is. It was the one that the worm gear rides on. I only mention it because I don't understand what "all the way up" means. As the only thing I could see were the teeth, so I lightly applied grease all the way around them. I did notice when I first opened it that there were globs of factory grease randomly. I tried to clean all that off though.

 

Would that simply be done with raising the worm housing a bit using the set screw? I did do that a bit until it seemed to turn OK. But I am not sure how tight it still is, or well how loose it can be. I do notice when I turn the axis there is lag between each direction before it starts moving. Is that what is considered backlash in this case?

I'm not that familiar with the CG-4 but I'm guessing it's the predecessor to the Avx... As they're all made by synta they all work on the same principle... The motor turns a gear on its shaft that is linked into a gear that's on the end of the worm shaft, the middle of the worm shaft is linked into the main gear( ring gear) which drives the mounts axis

You have two areas of meshing...

1. The cog on the motor to the worm on the worm shaft

2.  The worm mesh setting which sound like the one you done, which as you know needs very little adjustment from having quite abit of slack to fully locking up.. Did you test after tightening the bolts on the worm housing?

Another thing to look at is the locking nut on the bottom of the shaft where the bearing is, only needs to be tight enough not to have lateral play, don't over tighten as that can sandwich the axis up

Hope this helps

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8 minutes ago, Trippelforge said:

I got it to where it felt smooth and fairly easy to turn (via set screw adjustment), then tightened everything back down snug. 

Yes, what I found was that the tension on the bolts that hold the worm housing to the mount actually plays a role in the worm and gear mesh, not just the two worm bolts and grubscrew. Getting the tension right between all of these fixings is key. In the end the best solution for me was to hold the worm and housing square on the gear with my thumb whilst fastening up the housing fixing bolts till just snugged up and holding. Then make the mesh adjustment with the two bolts and grubscrew, I found that none of these bolts should be tight, just snugged up and holding. It's a fine balance to get it right and it took me quite a while. There are YouTube videos showing this done on an EQ5 which I think will be similar to your mount. Good luck 🙂.

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15 minutes ago, Trippelforge said:

Ya I took the housing to the worm gear off which also exposed the main axis gear. I cleaned the grease off of the worm gear, and most of the gunk on the main gear. Then lightly applied new grease, put it all back together and started tweaking it. I got it to where it felt smooth and fairly easy to turn (via set screw adjustment), then tightened everything back down snug. 

Considering I did this in 20 minutes total, I am obviously missing something. How did you test it while making the fine adjustments? I am going to assume just twisting the knob isn't accurate enough. Since I am going to obviously have to revisit this, any guidance on what I am looking for as an end result?

 

 

The backlash on the RA axis is weird. For instance I can turn the worm gear and advance the mount. When I stop I can rotate the axis slightly with my hands. I can rinse and repeat that process forever, however I "think" it gets harder to move when I fully crank down on the clutch lever. Each time I do it though it bottoms out on something, such as I can't just freely spin the axis around. We are talking like 8mm in movement. There is also "lag" during movement of the worm gear when I change direction, perhaps that is the backlash and the other is something loose?

If you fully crank on the clutch lever you push the ring gear sideways causing binding on parts of the axis travel

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15 minutes ago, newbie alert said:

I'm not that familiar with the CG-4 but I'm guessing it's the predecessor to the Avx... As they're all made by synta they all work on the same principle... The motor turns a gear on its shaft that is linked into a gear that's on the end of the worm shaft, the middle of the worm shaft is linked into the main gear( ring gear) which drives the mounts axis

You have two areas of meshing...

1. The cog on the motor to the worm on the worm shaft

2.  The worm mesh setting which sound like the one you done, which as you know needs very little adjustment from having quite abit of slack to fully locking up.. Did you test after tightening the bolts on the worm housing?

Another thing to look at is the locking nut on the bottom of the shaft where the bearing is, only needs to be tight enough not to have lateral play, don't over tighten as that can sandwich the axis up

Hope this helps

It helps, I believe the locking nut needs a special tool to loosen or tighten. At least from what diagrams I found, it has like 2 holes in it, it's weird. But I am going to assume if that needs adjustment the worm gear itself will wiggle back and forth. I did test after I tightened the bolts, I noticed that they had some effect on the movement. I backed off a bit and just made sure they were snug and not overly tight. That seemed to relieve a bit of pressure. It helps! Thank you!

10 minutes ago, Franklin said:

Yes, what I found was that the tension on the bolts that hold the worm housing to the mount actually plays a role in the worm and gear mesh, not just the two worm bolts and grubscrew. Getting the tension right between all of these fixings is key. In the end the best solution for me was to hold the worm and housing square on the gear with my thumb whilst fastening up the housing fixing bolts till just snugged up and holding. Then make the mesh adjustment with the two bolts and grubscrew, I found that none of these bolts should be tight, just snugged up and holding. It's a fine balance to get it right and it took me quite a while. There are YouTube videos showing this done on an EQ5 which I think will be similar to your mount. Good luck 🙂.

How can you tell when it's properly adjusted when tightening everything? Good to know that everything should only be snugged up, I wasn't sure how much torque was supposed to be used. I will look up some videos prior to tearing anything apart again. I should have then but was determined to quickly get it working again so I could drag it back outside. My son was pretty disappointed at that point. Thanks for helping me out!

 

10 minutes ago, newbie alert said:

If you fully crank on the clutch lever you push the ring gear sideways causing binding on parts of the axis travel

So how tight should the clutch lever be when everything is working properly? That kind of makes sense why I got the slipping to be a bit less as I guess the binding was keeping it more in place. 

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6 minutes ago, Trippelforge said:

It helps, I believe the locking nut needs a special tool to loosen or tighten. At least from what diagrams I found, it has like 2 holes in it, it's weird. But I am going to assume if that needs adjustment the worm gear itself will wiggle back and forth. I did test after I tightened the bolts, I noticed that they had some effect on the movement. I backed off a bit and just made sure they were snug and not overly tight. That seemed to relieve a bit of pressure. It helps! Thank you!

Sounds like you're talking about the locking nuts on the worm shaft, the part with the 2 holes is an outer case and the part that needs a special tool is underneath.. you only need to undo those if you want to change the bearings or if you have lateral movement on the worm shaft itself... That only if it's the part you're  talking about...

I try to find some pictures to save some crossed wires

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12 minutes ago, newbie alert said:

Sounds like you're talking about the locking nuts on the worm shaft, the part with the 2 holes is an outer case and the part that needs a special tool is underneath.. you only need to undo those if you want to change the bearings or if you have lateral movement on the worm shaft itself... That only if it's the part you're  talking about...

I try to find some pictures to save some crossed wires

That is what I was talking about, I don't think there is any lateral movement luckily. Now that everyone has helped I can dig into it and start trying to fix it up. 

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10 hours ago, Trippelforge said:

How can you tell when it's properly adjusted when tightening everything?

Being able to just turn the end of the worm with finger and thumb (without slo-mo cable or anything) is about right.

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