Help please! Dec axis stuck!

[ONIKKINEN]

4 minutes ago, oymd said:

When I’m back in London for sure. 
 

Im currently abroad, so no option but to use these. 

Try to clean all of the rollers and all the surfaces they roll on as thoroughly as possible and apply the new grease after that. There should be no feeling of grit or jerkiness in any of the bearings, if there are it means metal or rust has flaked off and is causing friction. Rust specks will act as sandpaper and will destroy the bearing, if it isn't already gone. It does look a bit rusty but i wouldn't call it ruined yet. But if not cleaned it will be ruined in use eventually. I think it can still be used without worry of further damage as long as its well cleaned and greased, but do keep in mind that eventually it should be replaced.

[oymd]

5 minutes ago, david_taurus83 said:

Are you sure that's what's blocking the axis from turning though? Even with a rusty bearing I'd have thought it would still turn albeit be very rough and stiff.

That’s just one part. When I’m done I’ll update 

[oymd]

6 minutes ago, ONIKKINEN said:

Try to clean all of the rollers and all the surfaces they roll on as thoroughly as possible and apply the new grease after that. There should be no feeling of grit or jerkiness in any of the bearings, if there are it means metal or rust has flaked off and is causing friction. Rust specks will act as sandpaper and will destroy the bearing, if it isn't already gone. It does look a bit rusty but i wouldn't call it ruined yet. But if not cleaned it will be ruined in use eventually. I think it can still be used without worry of further damage as long as its well cleaned and greased, but do keep in mind that eventually it should be replaced.

Done. 

[ONIKKINEN]

1 minute ago, oymd said:

Done. 

Does the dark stuff not come off? Difficult to tell without handling the bearing myself but looks slightly oxidized. If it feels slick when rolling then nothing to worry about, but if you can feel the dark stuff with your fingers or when rolling the bearing it should be taken off.

[oymd]

2 minutes ago, ONIKKINEN said:

Does the dark stuff not come off? Difficult to tell without handling the bearing myself but looks slightly oxidized. If it feels slick when rolling then nothing to worry about, but if you can feel the dark stuff with your fingers or when rolling the bearing it should be taken off.

I’ve brushed it well. It’s rolling freely. 
 

What is this ring btw?

is this the encoder ring?

are these markers encoders or rust marks?

[oymd]

1 hour ago, ONIKKINEN said:

Try to clean all of the rollers and all the surfaces they roll on as thoroughly as possible and apply the new grease after that. There should be no feeling of grit or jerkiness in any of the bearings, if there are it means metal or rust has flaked off and is causing friction. Rust specks will act as sandpaper and will destroy the bearing, if it isn't already gone. It does look a bit rusty but i wouldn't call it ruined yet. But if not cleaned it will be ruined in use eventually. I think it can still be used without worry of further damage as long as its well cleaned and greased, but do keep in mind that eventually it should be replaced.

@wimvb

Can I please check. 
 

Is this the final correct sequence at the bottom?

Bearing, then 2 smooth rings then clutch?

[ONIKKINEN]

1 hour ago, oymd said:

I’ve brushed it well. It’s rolling freely. 
 

What is this ring btw?

is this the encoder ring?

are these markers encoders or rust marks?

Looks like rust damage

[david_taurus83]

29 minutes ago, oymd said:

@wimvb

Can I please check. 
 

Is this the final correct sequence at the bottom?

Bearing, then 2 smooth rings then clutch?

I'd imagine the bearing runs between the 2 washers.

[wimvb]

The bearing between the washers, yes.

As per this old post (the second image shows the sandwich configuration of the washers and bearings. All bearings sit between two hardmetal washers, not directly against aluminium. Chemistry 101: two different metals in contact are more sensitive to corrosion. And aluminium is too soft and will eventually wear.

 

Edited January 6, 2022 by wimvb

[wimvb]

Btw, I also suspect that this is not the entire story. Corrosion can cause binding, but in your case there was a full stop. When you reassemble the DEC, before you put the clutch back, test if the DEC axis runs smoothly for one complete rotation. Then check again for each item you put back on.

Edited January 6, 2022 by wimvb

[wimvb]

1 hour ago, oymd said:

What is this ring btw?

is this the encoder ring?

are these markers encoders or rust marks?

This is just a washer (as you've probably figured out already). I'll post an image of the encoder in a minute.

(Was away from keyboard for a while)

[wimvb]

The encoder ring/disc is on the bottom side of the DEC head, as shown in this image. It is fixed to the DEC head and most likely made from glass, ceramic, or a highly polished metal.

[oymd]

46 minutes ago, wimvb said:

The encoder ring/disc is on the bottom side of the DEC head, as shown in this image. It is fixed to the DEC head and most likely made from glass, ceramic, or a highly polished metal.

 

1 hour ago, david_taurus83 said:

I'd imagine the bearing runs between the 2 washers.

 

1 hour ago, ONIKKINEN said:

Looks like rust damage

I would like to start by thanking everyone on this thread!

You have helped me immensely.

I think I also missed quoting @AstroKeith

So, I disassembled the mount tonight.
 

There was a large amount of RUST and the Dec axis was frozen at the part just above the clutch.
 

There was a fair amount of rust on the OUTSIDE OF THE CW BAR HOUSING and the INSIDE OF THE OPENING WHERE THE CW HOUSING EXITS THE MOUNT.

Now, you might ask, why the heck is there so much rust centered on the most dependant part it the mount?

I now can deduce what exactly happened?

Back in November last year, on my LAST imaging session, I left the mount outside in the garden to complete about 5 hours on the Rosette.

I planned to wake up early BEFORE the sprinklers came on in the garden at about 6am.
 

I did wake up on time, but I just missed the sprinklers by about 30 seconds.
 

There was very light water on the BOTTOM of the mount and tripod, but I managed to carry it back onto the porch away from the water.
 

I used my endoscope then to check inside the mount, and I could not see any water ingress, so did not really bother.
 

On looking on the OUTSIDE of the mount, there was some moist and damp at the area of the clutch.
 

I was travelling back to London in 48 hours, and had no plans to image again.
 

I used a hair blow dryer for about 20 minutes on the clutch area, and also wrapped it with a dew heater band for about 24 hours on maximum setting.
 

I travelled the next day, and COMPLETELY FORGOT ABOUT THE INCIDENT till I saw the rust tonight!!!

There must have been some ingress at the clutch area, and it had a full 40 days or so to rust happily until I tried to balance the Esprit a couple of days ago! 
 

I never gave the sprinklers incident a second thought, and I believed I got away with it!

Anyways, the reason that there was a few degrees of rotation, and then a KNOCK, is that there was rust seizing some kind of bearing on the INSIDE of the opening at the BOTTOM of the mount where the counter weight bar exits the mount. 
 

Tonght I could rotate it with my hand about a 10th of a full rotation either way, and then it would grind to a halt. 
 

I spend a good 4-5 hours brushing all the surfaces showing rust with a scotch brite sponge and a toothbrush with PLENTY of WD40

Everything was smooth and clean at the end  

As advised, I used White Lithium grease on all surfaces, and indeed, everything is smooth as butter now. 
 

Connected the mount in NINA, and slewed in all directions, sorted out the backlash and no binding to report. 
 

Will try an imaging session tomorrow. 
 

THANK YOU EVERYONE

Especially, thanks @wimvb

 

[wimvb]

Glad you got it sorted.

[wimvb]

I noticed I was a bit sloppy in my previous image of the encoder disc/ring. Your image shows it better.

Btw, did you swap the washer and bearing? It was a while since I regreased my mount, but I'm pretty sure that the bearing should be sandwiched between the two washers.

For future reference, here's en excellent write up by Scott Cunnington that I had almost forgotten.

http://reset.cbm8bit.com/uploads/files/magazines/59ae571fe9ecb_AZEQ6 Stripdown guide final.pdf

[ONIKKINEN]

1 hour ago, oymd said:

 

 

I would like to start by thanking everyone on this thread!

You have helped me immensely.

I think I also missed quoting @AstroKeith

So, I disassembled the mount tonight.
 

There was a large amount of RUST and the Dec axis was frozen at the part just above the clutch.
 

There was a fair amount of rust on the OUTSIDE OF THE CW BAR HOUSING and the INSIDE OF THE OPENING WHERE THE CW HOUSING EXITS THE MOUNT.

Now, you might ask, why the heck is there so much rust centered on the most dependant part it the mount?

I now can deduce what exactly happened?

Back in November last year, on my LAST imaging session, I left the mount outside in the garden to complete about 5 hours on the Rosette.

I planned to wake up early BEFORE the sprinklers came on in the garden at about 6am.
 

I did wake up on time, but I just missed the sprinklers by about 30 seconds.
 

There was very light water on the BOTTOM of the mount and tripod, but I managed to carry it back onto the porch away from the water.
 

I used my endoscope then to check inside the mount, and I could not see any water ingress, so did not really bother.
 

On looking on the OUTSIDE of the mount, there was some moist and damp at the area of the clutch.
 

I was travelling back to London in 48 hours, and had no plans to image again.
 

I used a hair blow dryer for about 20 minutes on the clutch area, and also wrapped it with a dew heater band for about 24 hours on maximum setting.
 

I travelled the next day, and COMPLETELY FORGOT ABOUT THE INCIDENT till I saw the rust tonight!!!

There must have been some ingress at the clutch area, and it had a full 40 days or so to rust happily until I tried to balance the Esprit a couple of days ago! 
 

I never gave the sprinklers incident a second thought, and I believed I got away with it!

Anyways, the reason that there was a few degrees of rotation, and then a KNOCK, is that there was rust seizing some kind of bearing on the INSIDE of the opening at the BOTTOM of the mount where the counter weight bar exits the mount. 
 

Tonght I could rotate it with my hand about a 10th of a full rotation either way, and then it would grind to a halt. 
 

I spend a good 4-5 hours brushing all the surfaces showing rust with a scotch brite sponge and a toothbrush with PLENTY of WD40

Everything was smooth and clean at the end  

As advised, I used White Lithium grease on all surfaces, and indeed, everything is smooth as butter now. 
 

Connected the mount in NINA, and slewed in all directions, sorted out the backlash and no binding to report. 
 

Will try an imaging session tomorrow. 
 

THANK YOU EVERYONE

Especially, thanks @wimvb

 

Thanks for the recap, it all makes sense now how this happened! The rust markings are only on one spot, presumably the spot that was towards the ground when the mount was sitting for 40 days. I think if it had been in use faster after the water damage, this wouldn't have been nearly as bad or even rusted at all since the water could have had a chance to drain off.

[oymd]

1 hour ago, wimvb said:

I noticed I was a bit sloppy in my previous image of the encoder disc/ring. Your image shows it better.

Btw, did you swap the washer and bearing? It was a while since I regreased my mount, but I'm pretty sure that the bearing should be sandwiched between the two washers.

For future reference, here's en excellent write up by Scott Cunnington that I had almost forgotten.

http://reset.cbm8bit.com/uploads/files/magazines/59ae571fe9ecb_AZEQ6 Stripdown guide final.pdf

Thanks Wim

Yes of course, it was silly of me to even ask that question. 
 

I reassembled with the bearing plate sandwiched between the 2 washer plates!

With regards to the encoder, I do not see any markings at all? Even on my image?

How does it work? I thought the encoder would have some kind of clear markings or grooves to tell whatever is scanning it some kind of positional information. 
 

And since I’ve dismantled and re constructed the mount tonight, do I need to do some kind of reset in software in EQMOD? Or just simply carry on like nothing happened?

[oymd]

38 minutes ago, ONIKKINEN said:

Thanks for the recap, it all makes sense now how this happened! The rust markings are only on one spot, presumably the spot that was towards the ground when the mount was sitting for 40 days. I think if it had been in use faster after the water damage, this wouldn't have been nearly as bad or even rusted at all since the water could have had a chance to drain off.

Yes, agreed. 
 

It was unfortunate that I left the mount overnight in the garden, and even more unfortunate that the water incident was followed by a 40 day period of non use. 
 

A perfect recipe for rust!

Very careless and silly on my part. 

[wimvb]

24 minutes ago, oymd said:

With regards to the encoder, I do not see any markings at all? Even on my image?

You can't see it in the image. There are very fine straight, dark lines radially. They are so narrow, you will need a magnifying glass to see the individual lines. When the axis rotates, these lines will pass a small sensor on the encoder pcb. This sensor consists of an led and a small light sensor. If a dark line passes the light sensor, no light is reflected back, whereas if a polished bright section between dark lines passes the sensor, light is reflected back into the sensor. The motor board software just keeps track of how many lines pass. Depending on the direction of rotation, a counter simply counts up or down. When you dis-/reassemble the mount, you have to make sure you keep this disc or ring clean and free of grease, otherwise the reflection is messed up.

[wimvb]

38 minutes ago, oymd said:

And since I’ve dismantled and re constructed the mount tonight, do I need to do some kind of reset in software in EQMOD? Or just simply carry on like nothing happened?

You don't have to do anything in EQMOD, as long as you don't use the encoders. The encoders are mainly used in SkyWatcher's Freedom Find function, where you can release the clutches to move the mount by hand, and the mount knows how far it moved. EQMOD doesn't use this functionality afaIk. But you need of course adjust any backlash setting if you use that in EQMOD. (PHD recommends against setting dec backlash in EQMOD.)

And of course, don't forget to turn off any sprinklers next time you set up. (At least now we can laugh about it.)

[oymd]

On 06/01/2022 at 20:45, ONIKKINEN said:

Does the dark stuff not come off? Difficult to tell without handling the bearing myself but looks slightly oxidized. If it feels slick when rolling then nothing to worry about, but if you can feel the dark stuff with your fingers or when rolling the bearing it should be taken off.

 

On 06/01/2022 at 22:01, ONIKKINEN said:

Looks like rust damage

 

On 06/01/2022 at 22:21, david_taurus83 said:

I'd imagine the bearing runs between the 2 washers.

 

On 06/01/2022 at 22:32, wimvb said:

The bearing between the washers, yes.

As per this old post (the second image shows the sandwich configuration of the washers and bearings. All bearings sit between two hardmetal washers, not directly against aluminium. Chemistry 101: two different metals in contact are more sensitive to corrosion. And aluminium is too soft and will eventually wear.

 

Sorry to resurrect this thread. 
 

Yesterday I had strange behaviour in RA, so I decided to completely strip the mount. DEC and RA. 

I followed the video to the letter, and it was actually easy, but I am STUCK AT A PROBLEM  

The RA axis is pristine, no rust at all. I replaced ALL the grease everywhere with the thick brown grease. 
 

I am faced with just one problem. 
 

And it’s not on the RA. It’s on the DEC. 

Last time when I dismantled the DEC, I did not touch the golden brass worm gear. 
 

This time I followed the video in detail, and tried to remove the golden brass worm gear on the DEC. 

It’s completely stuck!!

I had to go circumferentially very carefully and gently with a flat head screw driver to lift it off, and it took plenty of WD40 to get it done.
 

THERE IS NO RUST, but it was clearly stuck. In the video I can see it’s a VERY TIGHT FIT, but he removes it with ease, and puts it back with some pressure. 
 

In my case, I tried to put it back, but it will simply not go back in place without considerable force, and still gets stuck?!

Should I gently use a metal file and smooth the inner surface of the brass worm gear??

Or is it normal for it to be a VERY VERY tight fit so that it grabs the axis and forces it to rotate when the gear is rotating?

Edited January 15, 2022 by oymd

[ONIKKINEN]

16 minutes ago, oymd said:

 

 

 

Sorry to resurrect this thread. 
 

Yesterday I had strange behaviour in RA, so I decided to completely strip the mount. DEC and RA. 

I followed the video to the letter, and it was actually easy, but I am STUCK AT A PROBLEM  

The RA axis is pristine, no rust at all. I replaced ALL the grease everywhere with the thick brown grease. 
 

I am faced with just one problem. 
 

And it’s not on the RA. It’s on the DEC. 

Last time when I dismantled the DEC, I did not touch the golden brass worm gear. 
 

This time I followed the video in detail, and tried to remove the golden brass worm gear on the DEC. 

It’s completely stuck!!

I had to go circumferentially very carefully and gently with a flat head screw driver to lift it off, and it took plenty of WD40 to get it done.
 

THERE IS NO RUST, but it was clearly stuck. In the video I can see it’s a VERY TIGHT FIT, but he removes it with ease, and puts it back with some pressure. 
 

In my case, I tried to put it back, but it will simply not go back in place without considerable force, and still gets stuck?!

Should I gently use a metal file and smooth the inner surface of the brass worm gear??

Or is it normal for it to be a VERY VERY tight fit so that it grabs the axis and forces it to rotate when the gear is rotating?

I dont know if this gear is supposed to be able to move or not so wont comment on that, but definitely dont file anything off it.

You can heat fit it back in pretty easily. Its not rare for gears and fittings made of different materials to be stuck, and especially once they have been used. Heat the brass gear and cool down the inner axle and it will go in with less use of force. Maybe throw the axle in the fridge for a while and the brass gear into an oven at low heat. Dont heat it so hot that you cant touch it with gloves, so just a while in the oven. This way you can fit it back in pretty easily, but i dont know if its supposed to be able to move on its own so maybe dont do that until you know.

[oymd]

1 hour ago, ONIKKINEN said:

I dont know if this gear is supposed to be able to move or not so wont comment on that, but definitely dont file anything off it.

You can heat fit it back in pretty easily. Its not rare for gears and fittings made of different materials to be stuck, and especially once they have been used. Heat the brass gear and cool down the inner axle and it will go in with less use of force. Maybe throw the axle in the fridge for a while and the brass gear into an oven at low heat. Dont heat it so hot that you cant touch it with gloves, so just a while in the oven. This way you can fit it back in pretty easily, but i dont know if its supposed to be able to move on its own so maybe dont do that until you know.

Well, I spent the past hour using steel wool from the kitchen and copper paste to smooth the inner surface. 
Still would not fit. 
finally put the worm gear in boiling water for about 30 seconds, burnt my hands, and finally it fit!!

Strange. Once it’s in place, rotates smoothly as butter. 

[oymd]

1 hour ago, ONIKKINEN said:

I dont know if this gear is supposed to be able to move or not so wont comment on that, but definitely dont file anything off it.

You can heat fit it back in pretty easily. Its not rare for gears and fittings made of different materials to be stuck, and especially once they have been used. Heat the brass gear and cool down the inner axle and it will go in with less use of force. Maybe throw the axle in the fridge for a while and the brass gear into an oven at low heat. Dont heat it so hot that you cant touch it with gloves, so just a while in the oven. This way you can fit it back in pretty easily, but i dont know if its supposed to be able to move on its own so maybe dont do that until you know.

Ok. I’m ready to put everything back. 
 

I assembled the RA. IT ROTATES VERY VERY SMOOTHLY. 

ONLY PROBLEM IS: NO MATTER HOW TIGHT I PULL THE RA CLUTCH, it still moves with minimal force?

Is that normal, since I have not assembled the DEC yet?

I made sure that there was no grease on the black cardboard clutch plate? 
 

And tightened the black bottom ring and 3 grub screws VERY TIGHT?

[wimvb]

1 hour ago, oymd said:

And tightened the black bottom ring and 3 grub screws VERY TIGHT?

If you mean the RA lock nut, then this shouldn't be very tight. If it is to tight, it will make balancing more difficult, and the mount won't go very smooth with the clutch off. The three grub screws that hold the lock nut in place should pinch the RA shaft thread so the nut won't come loose.