Skywatcher HEQ5 Pro RA axis is stiff

[Ishan Mair]

Hi.

Its an one year old little used HEQ5 Pro mounting a Skywatcher 130PDS and Canon 1100D.

The RA axis is stiff to turn by hand even when it is unlocked. So Its difficult to balance as the axis just stays into its position even if it not properly balanced. There's no play in RA axis when it is locked. Mount is tracking okay though.

I've followed Astro-Baby's strip down guide to remove the polar scope, black nut and the tapered bearings. And yet there was no difference at all. The transparent and little sticky grease is there in moderate quantity.

Now I am clueless. Please help.

[StarryEyed]

The obvious question is was it always like that?

Assuming it was not then something has likely got into the bearings. Or between the rotating surfaces of the shaft and housing.

When you stripped the mount down did you

clean and repack the bearings

Debug and polish and bearing surfaces

I guess another question would be has the head been dropped oorhad a blow.

There are in truth many possibilities the cluth could be sticking etc etc.

A good clean and careful inspection should have sorted it out.

As you disassemble you should check to see when the movement frees up and then scrutinise the relevant parts.

Best of luck.

[Alien 13]

I dont know how the HEQ5 differs but on the EQ3/5 the RA setting circle is designed to introduce a lot of drag and unlocking it allows the RA axis to swing free.

Alan

[Thalestris24]

Hi

I had similar concerns however I just think it's a characteristic of the mount. If it slews quite happily and tracks and guides ok then maybe just leave well alone and be happy.

Louise

[StarryEyed]

To much torque will burn the motors out by design it should be free to move with the clutch disengaged.

[Ishan Mair]

When clutch is disengaged, and I try to rotate RA axis by hand, the motors dont move at all. It is only the RA shaft rotating in the base of mount. So I suspect the problem to be in the shaft and base not in the motors or worm wheels or anything.

[1parsec]

To much torque will burn the motors out by design it should be free to move with the clutch disengaged.

The motors in the HEQ5 pro are stepper motors and won't 'burn out' if overloaded,

When stalled they make a loud rattle as the motor misses steps and jumps between the poles.

[Ishan Mair]

Hi everyone.

The RA Axis on Skywatcher HEQ5 Pro was tight to rotate by hand when unclutched. Cant balance on RA Axis. So I took it apart. When i removed the RA shaft from housing, I found black grit formed by rubbing of brass cylinder with its housing.

The attached photos show black grit on cylinder and housing.  The cylinder seems to be out of centre in the third photo.

I removed it all, degreased and regreased it with yellow translucent lithium grease  and assembled it again. But no improvement in RA Axis stiffness. When I try to put brass cylinder back into housing, it stops at a point. It has to be turned around so that it can slip in.

I think that the housing is "undersized". Please help with this.

Ishan.

[Cornelius Varley]

I've merged the two threads together.
It seems that the ra housing has been badly machined or the ra bearing is out of alignment.

[Owmuchonomy]

Did you adjust the the fine adjusters (small Allen screws) to set the worm gear spacing as described on Astrobaby's site? It is a very fine adjustment and makes all the difference. It takes some trial and error to get the play correct but it's an important final fine tuning step.

[Thalestris24]

Hi

Hope you don't mind me butting in again. But FWIW mine doesn't move in RA as easy as it does in DEC with clutches loosened, so it takes more effort to unbalance it in RA. However, it's still possible for me to move the mount in RA (with no scope) using one hand (I'm only little!) and the rotation is smooth, if a little 'heavy' feeling. I can move it in RA with the scope attached using just one finger. Also tracks fine. I think it's really hard to convey what these things are like, or what they should be like, just in text and pictures. Maybe video is the answer to sharing such info! When I next rebalance mine I'll try and make a video of it 

Louise

[Ishan Mair]

Thanks for helping everyone.

I've merged the two threads together.
It seems the that the ra housing has been badly machined or the ra bearing is out of alignment.

Got it !!

Did you adjust the the fine adjusters (small Allen screws) to set the worm gear spacing as described on Astrobaby's site? It is a very fine adjustment and makes all the difference. It takes some trial and error to get the play correct but it's an important final fine tuning step.

The RA axis was stiff when the mount arrived. Have I misunderstood here? Does "worm gear spacing" have any role if RA clutch is off and I'm trying to rotate it by hand? Does "play" mean "With RA axis clutched there's any movement in the axis"? Sorry for noob questions.

so it takes more effort to unbalance it in RA. I can move it in RA with the scope attached using just one finger.

Louise,

but seems like mine takes almost a hand push with Skywatcher 130 PDS scope (3.6 kg)  and one counterweight. But it is not "free" by any means. It stays in almost any position I keep it in. A video will be helpful.

Can I use sandpaper on the housing? Or is there a way to correct the misalignment of the cylinder? Anyone tried it before?

Ishan.

[Cornelius Varley]

I would advise not to try and repair this yourself. If the mount is still under warranty you should return it to where you bought it for repair / replacement.

[Owmuchonomy]

As Peter says don't try and fix a major fault yourself. If the housing is badly machined that's a major fault, and a bit surprising. My point is to make sure you have done all the DIY adjustments correctly before assuming there is a major fault. Absolutely the worm gear adjustment will make a difference to rotation by hand or with the motors. If you can rotate the mount in RA with the motors without the motor clutch screaming at you then I doubt this adjustment is the issue. When my mount arrived for example the RA worm drive shaft lock nut was so loose it was rattling in the housing. It was a quick adjustment to fix it.

[StarryEyed]

The motors in the HEQ5 pro are stepper motors and won't 'burn out' if overloaded,

Yeah thats right.

[Ishan Mair]

Absolutely the worm gear adjustment will make a difference to rotation by hand or with the motors. If you can rotate the mount in RA with the motors without the motor clutch screaming at you then I doubt this adjustment is the issue.

The mount works okay with the motors. I have not noticed any binding or noise when rotating with motors. When I unlock the RA clutch and rotate RA axis, I see that the brass cylinder and the RA shaft at its center rotate together. Correct me if I am wrong. The motor drives the worm and that drives the RA shaft inside the clutched brass cylinder. So I dont understand how can worm be involved when the whole RA assembly is just turning in its housing.

Meanwhile, I have put in a lot of lithium grease and there was a little improvement.

Here's the video I've shot showing the problem. http://youtu.be/aqczPuRghEw

There was also a slight movement in RA axis when clutched.

Ishan.

[Dan13]

On 22/07/2014 at 10:06, Ishan Mair said:

The mount works okay with the motors. I have not noticed any binding or noise when rotating with motors. When I unlock the RA clutch and rotate RA axis, I see that the brass cylinder and the RA shaft at its center rotate together. Correct me if I am wrong. The motor drives the worm and that drives the RA shaft inside the clutched brass cylinder. So I dont understand how can worm be involved when the whole RA assembly is just turning in its housing.

Meanwhile, I have put in a lot of lithium grease and there was a little improvement.

Here's the video I've shot showing the problem. http://youtu.be/aqczPuRghEw

There was also a slight movement in RA axis when clutched.

Ishan.

Hi did you ever figure this out? I have the exact same issue...

[Ishan Mair]

 

6 hours ago, Dan13 said:

Hi did you ever figure this out? I have the exact same issue...

If the mount is under warranty, contact the seller.
I've tried something. I wouldn't say I its sorted. Frankly, I know almost nothing about how the mechanism works. So I wouldn't like to suggest anything. I'm sorry I can not help. You could try starting a similar topic. Others with knowledge will give good advice.

 

[newbie alert]

On 22/07/2014 at 10:06, Ishan Mair said:

The mount works okay with the motors. I have not noticed any binding or noise when rotating with motors. When I unlock the RA clutch and rotate RA axis, I see that the brass cylinder and the RA shaft at its center rotate together. Correct me if I am wrong. The motor drives the worm and that drives the RA shaft inside the clutched brass cylinder. So I dont understand how can worm be involved when the whole RA assembly is just turning in its housing.

Meanwhile, I have put in a lot of lithium grease and there was a little improvement.

Here's the video I've shot showing the problem. http://youtu.be/aqczPuRghEw

There was also a slight movement in RA axis when clutched.

Ishan.

The mount seems more fluid when you remove the scope to me... if it's new and still within warrenty then send it back.. the axis should be like what your DEC axis is

If it's not then the first thing id check is the locking ring on that axis, if it's too tight it can lock things up, if it's too loose then there's some lateral play.. hand tight is plenty..

[Ishan Mair]

2 hours ago, newbie alert said:

The mount seems more fluid when you remove the scope to me... if it's new and still within warrenty then send it back.. the axis should be like what your DEC axis is

If it's not then the first thing id check is the locking ring on that axis, if it's too tight it can lock things up, if it's too loose then there's some lateral play.. hand tight is plenty..

Of course, its not new anymore as that post was in 2014 🤣

My observation with my mount has been slightly different from almost everyone on this planet. I

I notice that when I hand tighten the RA nut, the axis is way too smooth for clutch to hold it. With clutch locked with enough force (confirmed that it does not touch the stop), I can just pull a cable little bit and it would slip. Balancing is a nightmare.

Now the interesting part. As I would gradually loosen the RA nut, the axis rotation becomes more and more dragged. Ultimately, when its too loose, lateral play shows up.

I have tried setting the RA lock nut up in between too smooth and too dragged, but have been not been successful.

Edited July 17, 2020 by Ishan Mair

[AstroMuni]

On 22/07/2014 at 10:06, Ishan Mair said:

Here's the video I've shot showing the problem. http://youtu.be/aqczPuRghEw

Hi Ishan,

From your video it looks as if having an unbalanced axis is pushing the bearing to one side and causing the slower movement. Whereas when you have nothing attached it moves freely.

 

[newbie alert]

13 minutes ago, AstroMuni said:

Hi Ishan,

From your video it looks as if having an unbalanced axis is pushing the bearing to one side and causing the slower movement. Whereas when you have nothing attached it moves freely.

 

Having the clutch too tight can force things to one side too

[Starflyer]

On 17/07/2020 at 10:57, Ishan Mair said:

Of course, its not new anymore as that post was in 2014 🤣

My observation with my mount has been slightly different from almost everyone on this planet. I

I notice that when I hand tighten the RA nut, the axis is way too smooth for clutch to hold it. With clutch locked with enough force (confirmed that it does not touch the stop), I can just pull a cable little bit and it would slip. Balancing is a nightmare.

Now the interesting part. As I would gradually loosen the RA nut, the axis rotation becomes more and more dragged. Ultimately, when its too loose, lateral play shows up.

I have tried setting the RA lock nut up in between too smooth and too dragged, but have been not been successful.

When you lubricated the brass worm wheel with lithium grease did you also put it onto the undercut / recess that the clutch tightens against?

This area should be completely free of grease / oil, as should the face of the brass button on the clutch.  The clutch relies on a brass to brass contact without lubrication, any grease will make the clutch less effective, even to the point where it slips easily. 

You should never have to tighten clutches really tight, in fact doing so can give you worse guiding as it's easy to distort things. The lightest clutch pressure needed to lock the axis against accidental slight knocks is all that's required. If you have to overtighten a clutch then it's not working properly.

[Ishan Mair]

23 hours ago, Starflyer said:

When you lubricated the brass worm wheel with lithium grease did you also put it onto the undercut / recess that the clutch tightens against?

This area should be completely free of grease / oil, as should the face of the brass button on the clutch.  The clutch relies on a brass to brass contact without lubrication, any grease will make the clutch less effective, even to the point where it slips easily. 

You should never have to tighten clutches really tight, in fact doing so can give you worse guiding as it's easy to distort things. The lightest clutch pressure needed to lock the axis against accidental slight knocks is all that's required. If you have to overtighten a clutch then it's not working properly.

There is not undercut in HEQ5 brass worm wheel. I think I didn't put grease on the worm wheel. But it could be that I polished the worm wheel too smooth while cleaning it. So now the clutch doesn't hold it.

On 17/07/2020 at 15:58, newbie alert said:

Having the clutch too tight can force things to one side too

But I was swinging the axis freely so clutch was unlocked. So it can't force the axis.

[newbie alert]

On 19/07/2020 at 15:19, Ishan Mair said:

 

But I was swinging the axis freely so clutch was unlocked. So it can't force the axis.

So adding weight forces it to lock up more... must be the locking nut, or you're missing a plastic washer or something? Have you taken the mount apart?