How much grease should be on your worm gears and RA axis gear?

[Trippelforge]

I have been struggling for awhile with my mounts RA axis binding up. It seems to always due it as temperatures drop, so I have taken it apart and checked various suggested things a few times. As well as spending a lot of time tweaking the RA worm gears tension. However I ran into ANOTHER binding episode last week, only this time it wasn't very cold (10'C). I was able to shut off the motor and manually spin the crap out of it and once turned back on it worked. I got to wondering this morning due to re-greasing it (superLube) in the beginning. Then cleaning some off after a second tear down on how much should actually be on the worm gear itself? This has been so frustrating, I wish I could afford a new mount.. =(

 

[ONIKKINEN]

If you put too much grease it will just get pushed out as the worm goes through all of the RA gear, so i would not worry about that. Unless you have some absurd mountain of grease in there that jams up everything but i doubt that.

But more importantly why are you trying to set the RA axis backlash to be as tight as possible? The axis is constantly under tension so backlash does not matter. For guiding purposes a guide impulse is really just a speed up or a speed down of the worm, but it never really reverses rotation so backlash shouldnt be an issue (unless your guide rate is above 1.0x, in which case you should lower it).

[Dr_Ju_ju]

Is the grease you are using rated for use at cold temperatures, as not all are ??

[Trippelforge]

1 hour ago, ONIKKINEN said:

If you put too much grease it will just get pushed out as the worm goes through all of the RA gear, so i would not worry about that. Unless you have some absurd mountain of grease in there that jams up everything but i doubt that.

But more importantly why are you trying to set the RA axis backlash to be as tight as possible? The axis is constantly under tension so backlash does not matter. For guiding purposes a guide impulse is really just a speed up or a speed down of the worm, but it never really reverses rotation so backlash shouldnt be an issue (unless your guide rate is above 1.0x, in which case you should lower it).

It was out about 1/2 a turn of the knob and I was getting frustrated with so much lag with my motor engagement. I wasn't sure how much backlash was normal, but when I slew with syncscan I end up no longer tracking correctly for a bit until and I guess the gear finally engaged. I have had to mess with the RA axis SO MUCH over the past month that it's been driving me crazy, as I keep having binding issues when the temps drop. And now for some random reason it did it again last weekend with warmer temps... I had to turn off the motor and manually move the knob around a bit, then re-engage to unbind it... it's been so annoying. 

Ya I think it's happing due to slewing back and forth a bit in order to center an object. And when I stop, it's drifting away, then it finally stops after 10 seconds or, but now I am off center again (during star alignment). 

 

44 minutes ago, Dr_Ju_ju said:

Is the grease you are using rated for use at cold temperatures, as not all are ??

I need to check it, I actually just bought what people told me around here, Superlube. 

[ONIKKINEN]

5 minutes ago, Trippelforge said:

Ya I think it's happing due to slewing back and forth a bit in order to center an object. And when I stop, it's drifting away, then it finally stops after 10 seconds or, but now I am off center again (during star alignment).

This is a bit of a problem. You need to always finish manual movements with the handcontroller by moving up and right. You need to first slew the star so that it sits to the bottom left, or wherever the left and down buttons take you (since the image can be inverted, flipped and all that) and only then center the star with the up and right buttons (and only those buttons, you go too far and you start again). This clears backlash and makes synscan work more accurately.

I take it you have not read the manual, as this is what you would find in it.😉

But also if that 10s length at sidereal rate is actually so long and not a guess its a problem and you are nowhere near a well set worm but then there would not be backlash as its so loose. Are you sure you are adjusting the correct thing here?

[Peter Drew]

Other than no grease I doubt whether grease will cause binding of the worm gear.  Assuming the mount in question is your CG4 and if it is similar to the Vixen Super Polaris mount, the the RA bearings might well be plain metal to metal contact.  Too tight a gear mesh could cause excess pressure between the mating surfaces and produce binding.  Cold will also make the axis harder to turn.   🙂 

[Trippelforge]

16 minutes ago, ONIKKINEN said:

This is a bit of a problem. You need to always finish manual movements with the handcontroller by moving up and right. You need to first slew the star so that it sits to the bottom left, or wherever the left and down buttons take you (since the image can be inverted, flipped and all that) and only then center the star with the up and right buttons (and only those buttons, you go too far and you start again). This clears backlash and makes synscan work more accurately.

I take it you have not read the manual, as this is what you would find in it.😉

But also if that 10s length at sidereal rate is actually so long and not a guess its a problem and you are nowhere near a well set worm but then there would not be backlash as its so loose. Are you sure you are adjusting the correct thing here?

I did not read the manual of course... lol

That makes sense on how to keep everything engaged while centering! I guess manuals are sometimes good for something!

Ya I can get the worm gear better engaged, and cut down the delay to only a few seconds but then it seems to be overly tight. I have been adjusting the set screw a tiny bit, then lightly tightening the other bolts. I keep doing this bit by bit until things feel OK. 

[ONIKKINEN]

16 minutes ago, Trippelforge said:

I did not read the manual of course... lol

That makes sense on how to keep everything engaged while centering! I guess manuals are sometimes good for something!

Ya I can get the worm gear better engaged, and cut down the delay to only a few seconds but then it seems to be overly tight. I have been adjusting the set screw a tiny bit, then lightly tightening the other bolts. I keep doing this bit by bit until things feel OK. 

Sounds like you are adjusting it right. Have you loosened the 2 screws holding the worm carrier bit to the mount housing? I mean the 2 in the bottom and not the 2 on both sides of the tiny setscrew. Those should not be overly tight, but also not quite finger loose to allow the worm to move in and out and not be fixed conpletely.

In my EQM35 which is very similarly built (backlash adjustment looks identical) i got RA backlash down to maybe 5 seconds but not much better than that because like yours it starts binding. There needs to be a bit of backlash left as the innards start to bind well before its completely bound if you try to make it perfect. Yours could just be like this. Check the gearbox too? The little gears connecting the worm to the stepper motor can be tilted cause extra friction.

The up and right trick might be enough for the troubles to go away though.

[Trippelforge]

31 minutes ago, ONIKKINEN said:

Sounds like you are adjusting it right. Have you loosened the 2 screws holding the worm carrier bit to the mount housing? I mean the 2 in the bottom and not the 2 on both sides of the tiny setscrew. Those should not be overly tight, but also not quite finger loose to allow the worm to move in and out and not be fixed conpletely.

In my EQM35 which is very similarly built (backlash adjustment looks identical) i got RA backlash down to maybe 5 seconds but not much better than that because like yours it starts binding. There needs to be a bit of backlash left as the innards start to bind well before its completely bound if you try to make it perfect. Yours could just be like this. Check the gearbox too? The little gears connecting the worm to the stepper motor can be tilted cause extra friction.

The up and right trick might be enough for the troubles to go away though.

I did loosen the bottom ones as well, and I also didn't put much torque on them at all when tightening as suggested. I have had two fairly long rounds of adjusting now. After awhile it kind of clicked how it was working, I wasn't sure about the set screw at first.

I did not check the stepper motor connection, that is not something I even considered. I didn't know it could tilt it, at least enough to make any difference. I will check that out tonight, although my belt isn't very tight and slightly squeezes inward when I pinch it. I am for sure going to do the up and right trick during my next session. That really makes sense!

Thanks for the help!

[Franklin]

One other point to check, is that the degree of mesh between the worm and gear may be fine and the grease is ok, but the actual worm may be in need of adjustment within the worm housing. If this is loose it will cause backlash and also binding if continually turned in one direction. Not sure about the CG4 but on the EQ5 and clones there is a nut at the end of the worm housing and when loosened the worm position within the housing can be tightened by using a lens spanner (there is an internal bolt with two small holes), once set retighten the holding bolt. If this is not adjusted correctly the worm can rock back and forth across the face of the gear teeth causing problems similar to yours.

[Trippelforge]

12 minutes ago, Franklin said:

One other point to check, is that the degree of mesh between the worm and gear may be fine and the grease is ok, but the actual worm may be in need of adjustment within the worm housing. If this is loose it will cause backlash and also binding if continually turned in one direction. Not sure about the CG4 but on the EQ5 and clones there is a nut at the end of the worm housing and when loosened the worm position within the housing can be tightened by using a lens spanner (there is an internal bolt with two small holes), once set retighten the holding bolt. If this is not adjusted correctly the worm can rock back and forth across the face of the gear teeth causing problems similar to yours.

Ya my mounts worm gear is the same, I noticed in a break down guide that the nut needed a special tool. Would I be able to feel it by wiggling it back and forth? It doesn't seem to have any play in it when I do. 

[Franklin]

If it wiggles then it's far too loose, but even if it doesn't wiggle it could still have play in it, which will take effect from the gear resistance and cause the worm to move across the gear teeth causing binding.

Setting up the worm and gear after a regrease is an exercise in frustration which is not pointed out in YouTube videos. Success is in finding a very fine balance between the worm lateral fixing, the worm/gear mesh and the tension on the housing holding bolts. It took me many hours to get it right but it is doable. One thing I found was to hold the worm housing square on the gear with my thumb whilst gradually tightening up the holding bolts, which should be just nipped up, then adjust the mesh, again don't overtighten anything. The worm needs to be held in the correct place, not forced into the gear and once in the correct place it can't be allowed to move. Persevere and I'm sure you'll triumph! (it's definitely nothing to do with the grease).

[Trippelforge]

12 minutes ago, Franklin said:

If it wiggles then it's far too loose, but even if it doesn't wiggle it could still have play in it, which will take effect from the gear resistance and cause the worm to move across the gear teeth causing binding.

Setting up the worm and gear after a regrease is an exercise in frustration which is not pointed out in YouTube videos. Success is in finding a very fine balance between the worm lateral fixing, the worm/gear mesh and the tension on the housing holding bolts. It took me many hours to get it right but it is doable. One thing I found was to hold the worm housing square on the gear with my thumb whilst gradually tightening up the holding bolts, which should be just nipped up, then adjust the mesh, again don't overtighten anything. The worm needs to be held in the correct place, not forced into the gear and once in the correct place it can't be allowed to move. Persevere and I'm sure you'll triumph! (it's definitely nothing to do with the grease).

I will go through it again with patience and a beer! I really am determined to get this damn thing figured out. The mount hasn't been too bad overall, so it's worth it to me to deal with the frustrations!

Thanks for the help!

[Franklin]

I'm no expert, but I've cleaned/ regreased and replaced bearings on a couple of mounts (CG5/EQ5) in the past and like you I found setting up the worms the most challenging part. I eventually found success, after several frustrating hours, by carrying out the reassembly in the following steps.

Step 1

With the worm and its housing off the mount adjust the lateral play of the worm. It doesn't need to spin freely, it just needs to turn smoothly with finger and thumb.

Step 2

Offer up the worm to the gear and whilst holding it square, close up the housing bolts symmetrically, just nipped up, not tightened. (if these are tightened down then the mesh adjustment will fail as the housing needs to move to allow the mesh adjustments).

Step 3

Adjust the worm/gear mesh using the single push set-screw and the two pull bolts. The set-screw pushes the worm away from the gear and the two bolts pull the worm on to the gear. Finding this balance is the tricky part but adjusting the two bolts symmetrically is key. If one is screwed in more than the other then the worm will be forced out of square with the gear.

Step 4

Once the mesh adjustment has been made you can test it by turning the end of the worm with just finger and thumb (no slo-mo knob) and if it turns smoothly but with some resistance, that is about right. Once you're happy with the adjustments give the two housing fixing bolts a slight tightening to hold your adjustments in place.

Good luck.

 

Edited February 8, 2023 by Franklin

[Trippelforge]

15 hours ago, Franklin said:

I'm no expert, but I've cleaned/ regreased and replaced bearings on a couple of mounts (CG5/EQ5) in the past and like you I found setting up the worms the most challenging part. I eventually found success, after several frustrating hours, by carrying out the reassembly in the following steps.

Step 1

With the worm and its housing off the mount adjust the lateral play of the worm. It doesn't need to spin freely, it just needs to turn smoothly with finger and thumb.

Step 2

Offer up the worm to the gear and whilst holding it square, close up the housing bolts symmetrically, just nipped up, not tightened. (if these are tightened down then the mesh adjustment will fail as the housing needs to move to allow the mesh adjustments).

Step 3

Adjust the worm/gear mesh using the single push set-screw and the two pull bolts. The set-screw pushes the worm away from the gear and the two bolts pull the worm on to the gear. Finding this balance is the tricky part but adjusting the two bolts symmetrically is key. If one is screwed in more than the other then the worm will be forced out of square with the gear.

Step 4

Once the mesh adjustment has been made you can test it by turning the end of the worm with just finger and thumb (no slo-mo knob) and if it turns smoothly but with some resistance, that is about right. Once you're happy with the adjustments give the two housing fixing bolts a slight tightening to hold your adjustments in place. 

Good luck.

 

Thank you very much for breaking it down for me! The one thing I did notice on there was in relation to the pull bolts. I didn't tighten anything down that much and was fairly careful. But I didn't really think that I went into full on precision mode to make sure the housing was perfectly squared. I did alternate between each, but still didn't pay much attention to it. If I did not have it squared up perfectly I assume that might be why it was tightening up during usage, which also is why turning the knob back and forth with a bit of irritation had fixed it... as I suppose it reseated it?

Ya this is for sure a PITA, but I am glad to hear I am not the only one who has gotten frustrated by it. 

I appreciate your (and everyones) help! It looks like clear skies will be here Saturday, although... the damn temperature is going to drop to -6C which means the cold will probably lock it up again on it's own... /sigh

 

[newbie alert]

On opening the mount back up did the grease get built up in a certain area of the worm? If so then you can reduce it by this amount that you put in next time, no need to fill up all the threads ... 

Lots of areas within the mount can cause it to bind but let's say it is from the worm adjustments, if you set it unloaded from inside the house and presume it's 15-20 degrees, then trying to run it at -2,-5 as it has been lately that adjustment could be way out..

Things to check..

Lateral play on the worm spindle

Bearings on the worm spindle

Locking nut on the  Ra shaft not overtightened

  Also factory set I've never found the worm central to the ring gear 

[Franklin]

11 minutes ago, Trippelforge said:

The one thing I did notice on there was in relation to the pull bolts. I didn't tighten anything down that much and was fairly careful.

Yes, even if the mesh of the worm/gear was ok before regrease, thinking that to just leave them as they were and put them back as they were is not viable. The tension of the worm/gear mesh is dependent on the placing and tightness of the housing fixing bolts and getting them back to where they were is easier said than done. Once dismantled for regrease it all needs setting up from scratch again I'm afraid.