EQ6 dec axis 'tight'

[tooth_dr]

Looking some advice for this evening please, when I hope to finish this saga that was stripping and regreasing my EQ6.

 

The DEC AXIS was always tight feeling even before I messed around.  By tight I mean that it can be turned ok by hand but there is some resistance; it certainly doesnt spin freely.  I stripped it all down, cleaned and regreased, and replaced all the washers etc as previous, and it's still tight.

If I loosen the CW shaft collar so that it's not holding the dec shaft - its the same tightness.

If I loosen the worm gear, out of contact - it's the same tightness.  If I gradually tighten the worn gear, there is say 2mm of rotational movement in the axix (clutches locked) which gradually goes to no movement - this is my interpretation of the dec axis adjusted properly.  It is still the same tightness to rotate.  This stiffness is consistent throughout the whole 360o rotation.

All the bearings appear fine upon inspection and all are turning ok.  But they are all sealed anyway so should be ok.

I've checked the motor gear mesh and adjusted this too.

 

I would be very grateful if anyone could suggest a list of things to check, unless of course this is totally fine.

I've connected it to the 12v and it turns fine through 360o.

 

I'm just worried that if too tight it will burn out the motors or what not.

 

Thanks in advance

Adam.

[LightBucket]

Hi,

it does sound like it’s the worm gear is too tight, as you say it is the same even with the counterweight shaft locking collar loosened...

the CW bar locking collar should not be too tight, just enough to take the play out of the bottom bearing, and then maybe another 1/8 of a turn, mine was done like that, but it actually still tighten another 1/4 to 1/2 turn if I wanted, but it’s only there to take out the play and hold the bearings in position. If I spin mine with clutch off and just the saddle attached it will spin maybe 1/4 of a rev and come to a stop, so I would say it’s nice and free, but not loose at all...but I guess that a matter of interpretation really....be interested to know how others fair with this. But one thing I do notice with mine, is there is a spot when turning the Dec axis that is very slightly tighter than the rest when rotating...

also if you power up with nothing mounted and slew the scope, if you can see the amps being used while slewing, if it is binding anywhere you will see the power go up and then back down...., mine uses approx 0.8 AMPS when stationary, when slewing on full speed it goes to approx 1.7 Amps, and stays around this for a full 360 degree rev, on both axis, so that tells me it is not binding at all, or at least not enough to need more power to move, it’s a good test...

 

[LightBucket]

One other thing to check, if the CW shaft collar has been tightened to tight in the past, and forced the bottom chamfered bearing into the mount too much, to check loosen the CW shaft collar and the bearing should just drop out quite easily...if it doesn’t, then it would be a good idea to get that out and re seat...and re set the CW shaft collar..

[tooth_dr]

12 minutes ago, LightBucket said:

Hi,

it does sound like it’s the worm gear is too tight, as you say it is the same even with the counterweight shaft locking collar loosened...

the CW bar locking collar should not be too tight, just enough to take the play out of the bottom bearing, and then maybe another 1/8 of a turn, mine was done like that, but it actually still tighten another 1/4 to 1/2 turn if I wanted, but it’s only there to take out the play and hold the bearings in position. If I spin mine with clutch off and just the saddle attached it will spin maybe 1/4 of a rev and come to a stop, so I would say it’s nice and free, but not loose at all...but I guess that a matter of interpretation really....be interested to know how others fair with this. But one thing I do notice with mine, is there is a spot when turning the Dec axis that is very slightly tighter than the rest when rotating...

also if you power up with nothing mounted and slew the scope, if you can see the amps being used while slewing, if it is binding anywhere you will see the power go up and then back down...., mine uses approx 0.8 AMPS when stationary, when slewing on full speed it goes to approx 1.7 Amps, and stays around this for a full 360 degree rev, on both axis, so that tells me it is not binding at all, or at least not enough to need more power to move, it’s a good test...

 

How do I go about testing amps being drawn?  Connect a multimeter across the terminals when its slewing?  Also the axis appears to be stiff when the worm gear is not in contact as far as I can see, but will double check later.

[tooth_dr]

10 minutes ago, LightBucket said:

One other thing to check, if the CW shaft collar has been tightened to tight in the past, and forced the bottom chamfered bearing into the mount too much, to check loosen the CW shaft collar and the bearing should just drop out quite easily...if it doesn’t, then it would be a good idea to get that out and re seat...and re set the CW shaft collar..

The chamfered bearing just drops out when I remove the dec axis, does not appear to be tight.  The sloped collar doesnt come out (it did come out of the RA axis).

[LightBucket]

Well my bench power supply has a read out on the front, so it’s easy for me, so not really sure how you would do it...do t think a multi metre across the terminal will work, but electronics is not my strong point so maybe someone else will have some input there...

I just found it a really good way of checking, I would check all else first and make sure it’s not a mechanical issue somewhere...bad clutch, binding bearing or something to tight...sorry if I am stating the obvious....  But if it was tight before you started, then it’s nothing you have done during your re grease...

My money is on the bottom bearing being too tight...

[spillage]

I would remove the bottom bearing and give it a good clean and regrease. When you tighten it back up wind up the collar do not just tighten it up in one go. Wind it in and then fully rotate the axis and keep doing this till the dec feels tight then back it off a bit. If this bearing is not sitting correctly then it can cause the dec to be tight. That is what I have found.

Edit: if the clutch is released I am sure they worm will not be rotated so that would not be your issue.

[LightBucket]

Yes that is correct, if the clutch is released it will NOT be the worm, as said above.

When you say the sloped collar, what do you mean there, if you take the bottom chamfered bearing out, and then Re fit as suggested above see how it feel then, when tightening the collar, put your ear to the mount, and you other hand on the saddle and gently rock the saddle while tightening the collar slowly you will hear the play in the bearing and shaft slowly disappear, when gone just tighten 1/8 more of a turn, and leave at that..

[spillage]

It may also help if once you have the collar on the thread tilt the RA so the mount is as vertical as you can get it. This should help the bearing sit as central as possible. If you tighten this up more do you get more resistance.

Sorry another thought. Have you had the mount from new. It could be that a spacer is missing so it might be worth looking at the hypertune instructions on astrobaby's site. This would show if that was the case.

[tooth_dr]

7 minutes ago, spillage said:

I would remove the bottom bearing and give it a good clean and regrease. When you tighten it back up wind up the collar do not just tighten it up in one go. Wind it in and then fully rotate the axis and keep doing this till the dec feels tight then back it off a bit. If this bearing is not sitting correctly then it can cause the dec to be tight. That is what I have found.

Edit: if the clutch is released I am sure they worm will not be rotated so that would not be your issue.

Just to clarify - the bottom bearing as in the sloped one that goes at the end of where the CW would go.  I've it filled with synthetic + PTFE grease, I find it hard to turn with my fingers.  This could be the reason for my problems?

[LightBucket]

Yes I have always done mine in the vertical position, as you say it will keep the bearing flat and should seat correctly..

[tooth_dr]

2 minutes ago, spillage said:

It may also help if once you have the collar on the thread tilt the RA so the mount is as vertical as you can get it. This should help the bearing sit as central as possible. If you tighten this up more do you get more resistance.

Sorry another thought. Have you had the mount from new. It could be that a spacer is missing so it might be worth looking at the hypertune instructions on astrobaby's site. This would show if that was the case.

I bought the mount new.  There were two teflon washers on the big brass wheel, but AB guide only shows one.

[LightBucket]

1 minute ago, tooth_dr said:

Just to clarify - the bottom bearing as in the sloped one that goes at the end of where the CW would go.  I've it filled with synthetic + PTFE grease, I find it hard to turn with my fingers.  This could be the reason for my problems?

Yes that is correct, just wondered what you meant when you said the bearing came out, but the sloped collar did not..? What is the sloped collar...

Sounds like you have too much grease in there, mine had a light covering on the outside of the bearing...!

[tooth_dr]

5 minutes ago, LightBucket said:

Yes that is correct, if the clutch is released it will NOT be the worm, as said above.

When you say the sloped collar, what do you mean there, if you take the bottom chamfered bearing out, and then Re fit as suggested above see how it feel then, when tightening the collar, put your ear to the mount, and you other hand on the saddle and gently rock the saddle while tightening the collar slowly you will hear the play in the bearing and shaft slowly disappear, when gone just tighten 1/8 more of a turn, and leave at that..

 

I'll attached a few photos here in a minute and hopefuly get to the bottom of all this!  I appreciate all your help.

[LightBucket]

2 minutes ago, tooth_dr said:

 

I'll attached a few photos here in a minute and hopefuly get to the bottom of all this!  I appreciate all your help.

No problem, that what we are all here for..

[spillage]

The number and thickness can vary. It may be that at the factory the wrong size shim was used. I must admit to smothering my bottom bearing in tf2 grease and it seem fine. Initially it had a tight spot at about 11o'clock but a little slack removed it.

It might be that if you can balance your scope then it's just one of those niggles you learn to live with.

[spillage]

No worries...its better than doing what I am supposed to be doing...WORK..

[tooth_dr]

@LightBucket @spillage

I've attached photos of the parts as I stripped them out, and after cleaned.  There arent any of the tapered bit where the tapered bearing seats into on the dec axis, but I'll have a look at it later, cant see it being too far in as it can only go so far.  Maybe I've too much thick grease packed into it and it's making it feel stiff.  I'll soak it later and remove all the grease, just to see that is the problem.

Photo 1 - taperered dec bearing on removal

Photo 2 - dec gear and bearing on removal

Photo 3 - parts cleaned before assembly

Photo 4 - RA axis on removal of tapered bearing - corrosion noted

Photo 5 - tapered bearing from RA axis - with corrosion.

Photo 6 - paint or glue on sloped collar - this is the sloped collar that I was referring to earlier - it simply fell out of the RA axis here, so I caefully removed the glue and set it back in.

[spillage]

The rust on the RA looks bad but sure it will clean up okay and I guess the RA is not the issue here.

If all the dec bearing feel okay then I would put a bit of grease around the brass worm gear just in case its binding on clutch. Put it back together going easy on tightening the dec up and try it with your scope attached to give you a better feel.

[tooth_dr]

5 hours ago, spillage said:

The rust on the RA looks bad but sure it will clean up okay and I guess the RA is not the issue here.

If all the dec bearing feel okay then I would put a bit of grease around the brass worm gear just in case its binding on clutch. Put it back together going easy on tightening the dec up and try it with your scope attached to give you a better feel.

So this might help you to help me - I've removed the lower nut and bearing and it's still exactly the same tightness to turn the DEC axis. 

[tooth_dr]

The gold gear turns freely below when set onto the mount. 

[tooth_dr]

Photos of DEC axis parts:

 

[spillage]

I am sure this must be a tight bearing but I really think you need to measure the spacing as per here and reading here proves that the mounts can come from the factory with spacer issues.

The brass gear and worm is connected mechanically and only effect the dec axis once the clutch is applied and locked (sorry kinda thinking out loud).

If the clutch is released then the shaft rotates within the bearings.

How do the bearing feel when out of the mount.

 

edit:

29 minutes ago, tooth_dr said:

So this might help you to help me - I've removed the lower nut and bearing and it's still exactly the same tightness to turn the DEC axis. 

Have you wound the clutch right out?

[tooth_dr]

22 minutes ago, spillage said:

I am sure this must be a tight bearing but I really think you need to measure the spacing as per here and reading here proves that the mounts can come from the factory with spacer issues.

The brass gear and worm is connected mechanically and only effect the dec axis once the clutch is applied and locked (sorry kinda thinking out loud).

If the clutch is released then the shaft rotates within the bearings.

How do the bearing feel when out of the mount.

 

edit:

Have you wound the clutch right out?

Bearings are smooth.  All the 4 bearings feel the same on all axes so I'm going to assume that they are ok. 

 

My digital callipers only measure to 0.1mm but I'll take them anyway and see what the result is.

 

thanks for you patience. 

[newbie alert]

What's the red grease please?