Help please! Dec axis stuck!

[ONIKKINEN]

2 minutes ago, wimvb said:

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.

Actually my brand new mount has this issue, the locknut is too tight. Difficult to balance with stiction in RA with the clutch off. What is the proper tool to open this if i may ask?

[wimvb]

10 minutes ago, ONIKKINEN said:

What is the proper tool to open this if i may ask?

On most skywatcher mounts, the RA lock nut is itself locked in place by three small grub screws around its circumference (you'll need to check this on your mount). These grub screws need to be loosened or removed before the lock nut can be loosened, or you'll strip the thread on the RA shaft. The lock nut probably has two holes on either side of the shaft. The video in the beginning of this thread shows this. You need a tool that can grip the lock nut in these holes, and then you can loosen the nut by no more than a quarte of a turn. Just enough that the RA axis moves a little more freely. The nut shouldn't be so loose as to introduce play in the RA axis. There's a reason for it being where it is, so this is a balancing act.

Hope this helps.

[ONIKKINEN]

9 minutes ago, wimvb said:

On most skywatcher mounts, the RA lock nut is itself locked in place by three small grub screws around its circumference (you'll need to check this on your mount). These grub screws need to be loosened or removed before the lock nut can be loosened, or you'll strip the thread on the RA shaft. The lock nut probably has two holes on either side of the shaft. The video in the beginning of this thread shows this. You need a tool that can grip the lock nut in these holes, and then you can loosen the nut by no more than a quarte of a turn. Just enough that the RA axis moves a little more freely. The nut shouldn't be so loose as to introduce play in the RA axis. There's a reason for it being where it is, so this is a balancing act.

Hope this helps.

Thought so, grubscrews are off but still it wont budge with my McGyver'd tools made with what i have (some bolts and leverage, bolts broke off). Probably need to head to the hardware store to buy the proper pliers for this. Its unnecessarily tight for me, but its only an issue with the latitude set to higher than 45, so where gravity no longer helps with the movement. The synta factory at Taiwan latitudes does not have this issue since its at an easier angle where gravity helps with RA movement. At 60 degrees north not so much.

[oymd]

21 minutes ago, ONIKKINEN said:

Thought so, grubscrews are off but still it wont budge with my McGyver'd tools made with what i have (some bolts and leverage, bolts broke off). Probably need to head to the hardware store to buy the proper pliers for this. Its unnecessarily tight for me, but its only an issue with the latitude set to higher than 45, so where gravity no longer helps with the movement. The synta factory at Taiwan latitudes does not have this issue since its at an easier angle where gravity helps with RA movement. At 60 degrees north not so much.

CIRCLIP PLIERS. THE BENT ONES

[oymd]

1 hour ago, ONIKKINEN said:

Actually my brand new mount has this issue, the locknut is too tight. Difficult to balance with stiction in RA with the clutch off. What is the proper tool to open this if i may ask?

 

56 minutes ago, wimvb said:

On most skywatcher mounts, the RA lock nut is itself locked in place by three small grub screws around its circumference (you'll need to check this on your mount). These grub screws need to be loosened or removed before the lock nut can be loosened, or you'll strip the thread on the RA shaft. The lock nut probably has two holes on either side of the shaft. The video in the beginning of this thread shows this. You need a tool that can grip the lock nut in these holes, and then you can loosen the nut by no more than a quarte of a turn. Just enough that the RA axis moves a little more freely. The nut shouldn't be so loose as to introduce play in the RA axis. There's a reason for it being where it is, so this is a balancing act.

Hope this helps.

My problem is the other way around. 
the RA is loose and won’t lock

[wimvb]

 

3 minutes ago, oymd said:

 

My problem is the other way around. 
the RA is loose and won’t lock

Have you checked if the RA assembly sits properly in its housing? If so, then the only thing I can think of is that the nut may need to be tightened a little more. The clutches on the AZ-EQ6 press worm ring to the mount head front to back, unlike other EQ6 mounts (including the EQ6-R) which has small brake blocks that press to one side of a brass cylinder. So, unless you would forget to put a washer or bearing back where it should be, something is preventing the compression.

I think that Haynes should publish mount manuals. If they can make one for the Millenium Falcon, a SkyWatcher mount shouldn't be much of a challenge

[wimvb]

@oymd

Btw, I wouldn't put grease on the surface of the RA worm ring. The whole clutch mechanism depends on that the worm ring gets compressed to the DEC housing and the bearing between the ring and this housing. Grease can prevent enough compression. So, on the RA shaft from DEC housing outwards:

metal washer, greased bearing, metal washer, (no grease), brass worm ring with only grease around its gear teeth NOT on top or bottom, (no grease), clutch plate.

[wimvb]

@ONIKKINEN, I forgot about this; the RA lock nut has a bearing between it and the housing. This means that even if the lock nut is tight, the RA axis should still rotate. But otoh, if you can't remove it even with much force, you can definitely loosen it and then tighten it again (with a smaller tool). But there shouldn't be any play here.

[oymd]

12 hours ago, wimvb said:

@oymd

Btw, I wouldn't put grease on the surface of the RA worm ring. The whole clutch mechanism depends on that the worm ring gets compressed to the DEC housing and the bearing between the ring and this housing. Grease can prevent enough compression. So, on the RA shaft from DEC housing outwards:

metal washer, greased bearing, metal washer, (no grease), brass worm ring with only grease around its gear teeth NOT on top or bottom, (no grease), clutch plate.

I rechecked. Grease is only in the edges and not the surfaces. 
 

I am thinking that I am doing the tightening of the lock nut wrong. 
 

There are THREE ELEMENTS:

1- The silver collar with the holes in it

2- The black lock ring

3- three grub screws. 
 

I am confused about the SILVER COLLAR and where it’s starting position should be?

I think my problem is here. 
 

On reassembly, SHOULD THE SILVER COLLAR be screwed all the way clockwise? Clockwise RELEASES THE CLUTCH  and exposes more of the BLACK LOCK NUT and moves the silver collar up flush with the mount  

 

Or should I assemble with the SILVER COLLAR screwed OUT COUBTERCLOCKWISE? Counterclockwise STIFFENS THE RA and covers more of the black lock nut?

As you can see in the Pic, there is now a SPACE between the silver collar and the mount, which I think is WRONG?

So should I try to redo with the silver collar screwed all the way UP TO THE MOUNT BODY IN THE RELEASE POSITION?

 

Edited January 16, 2022 by oymd

[wimvb]

The ring with the holes is the RA clutch. For me the difference between engaged and not engaged is only 1/4 turn or less. Leave the clutch released when you put the lock nut (black, with 4 holes) back in.

  

So: RA clutch not tightened, but neither removed. Screw lock nut (black) all the way in and locked in position with grub screws. Then tighten the clutch.

I'm not sure that the clutch ring can be completely removed without unscrewing the Phillips screws in the chrome ring on the mount (just visible in my last image behind the clutch ring). At least afaIk, it isn't necessary to remove it completely.

When I engage the clutch to lock the RA and DEC, I can still rotate the RA axis when I push against the counter weight bar, with a few kilograms of force (guesstimate). The same for the DEC clutch if I push against my scope, with about the same force.

[wimvb]

I just went out to check the RA clutch mechanism. The clutch ring can be unscrewed a few mm, but not completely, which makes sense. This mechanism works as a bolt and a nut. The ring with handle that we see is the nut. Hidden inside the mount is its counter part, the bolt. When you loosen the RA clutch, you turn the ring clockwise and pull the hidden bolt half of the mechanism towards you, away from the RA worm ring. The bolt which pressed against the RA worm ring with its clutch plate, is now lifted from that. Here's a sketch that helps to explain.

The mechanism is fixed in place, and you can't remove the chrome clutch ring, unless you loosen the Phillips screws that hold the clutch mechanism in place. There is absolutely no need to do that.

For completeness, the DEC clutch is a little simpler. Here, the part that we see and turn itself presses against the DEC worm gear, locking it. You can't unscrew this clutch completely, because it is held in place by the ring that holds the counter weight bar in position.

I hope this clarifies things a bit.

[oymd]

9 hours ago, wimvb said:

I just went out to check the RA clutch mechanism. The clutch ring can be unscrewed a few mm, but not completely, which makes sense. This mechanism works as a bolt and a nut. The ring with handle that we see is the nut. Hidden inside the mount is its counter part, the bolt. When you loosen the RA clutch, you turn the ring clockwise and pull the hidden bolt half of the mechanism towards you, away from the RA worm ring. The bolt which pressed against the RA worm ring with its clutch plate, is now lifted from that. Here's a sketch that helps to explain.

The mechanism is fixed in place, and you can't remove the chrome clutch ring, unless you loosen the Phillips screws that hold the clutch mechanism in place. There is absolutely no need to do that.

For completeness, the DEC clutch is a little simpler. Here, the part that we see and turn itself presses against the DEC worm gear, locking it. You can't unscrew this clutch completely, because it is held in place by the ring that holds the counter weight bar in position.

I hope this clarifies things a bit.

Job done!

Third strip down in three days!!

So, it turns out the issue was with the BLACK SCREW LOCK NUT. 

While disassembled, I threaded the three grub screws into it, and observed, on the inner circumference, how far they went. 
 

Turns out that TWO of the three grub screws were not screwing in all the way. They would stop about 2/3 the way, so they would not lock onto the inner barrel. 
 

Using a 2mm Allen key, I cleaned out the three holes. There was some brown muck in there. A touch of grease on the inner threads of the three holes, and reassembled the whole mount. 
 

This time I noticed that the grub screws required MANY more rotations. 
 

And VOILA!

Job done. It’s now about 1/4 of a turn on the RA clutch from disengaged to locked. 
 

Sadly, I have one causality. 
 

The thumb screw has stripped, as I must have used in in anger and haste a thousand times over the past three days!

 

Using an M6 socket cap screw instead!

Happy days!!

I’m taking a break, then will address the inevitable HORRIFIC BACKLASH both in RA and DEC!

Thanks you all for your great help and contribution! Much appreciated!

Especially @wimvb

👏

Edited January 17, 2022 by oymd

[oymd]

On 16/01/2022 at 17:23, wimvb said:

I just went out to check the RA clutch mechanism. The clutch ring can be unscrewed a few mm, but not completely, which makes sense. This mechanism works as a bolt and a nut. The ring with handle that we see is the nut. Hidden inside the mount is its counter part, the bolt. When you loosen the RA clutch, you turn the ring clockwise and pull the hidden bolt half of the mechanism towards you, away from the RA worm ring. The bolt which pressed against the RA worm ring with its clutch plate, is now lifted from that. Here's a sketch that helps to explain.

The mechanism is fixed in place, and you can't remove the chrome clutch ring, unless you loosen the Phillips screws that hold the clutch mechanism in place. There is absolutely no need to do that.

For completeness, the DEC clutch is a little simpler. Here, the part that we see and turn itself presses against the DEC worm gear, locking it. You can't unscrew this clutch completely, because it is held in place by the ring that holds the counter weight bar in position.

I hope this clarifies things a bit.

Update.

Tonight I fine tuned BACKLASH on both RA and DEC.

There is no play now whatsoever in both axis.

I connected the mount in NINA, and slewed to all extremes in all 4 directions to make sure there is no stiction or issues.

Everything seems perfect.

Its a clear night, so I thought I might take the mount out for a CALIBRATION first in PHD2, and see what guiding might be like on a short imaging run.

The issue is: The mount will NOT PARK to the home position? DEC parks just fine, but RA does not park?

In EQMOD, I clicked the RESYNC EQMOD encoder button to tell EQMOD of the home position, but still no parking in RA?

Do the issues ever end?

[wimvb]

Just turn the encoders off. They are only needed if you intend to manually move the mount after you’ve done a star alignment. If you use eqmod, you don’t do that anyway. Also reset any mount model in eqmod. What you do want to test now is guiding.

You also don’t need the auxilary encoder on RA. This is only used if you use the mount’s PPEC. And PPEC is incompatible with guiding.

[oymd]

55 minutes ago, wimvb said:

Just turn the encoders off. They are only needed if you intend to manually move the mount after you’ve done a star alignment. If you use eqmod, you don’t do that anyway. Also reset any mount model in eqmod. What you do want to test now is guiding.

You also don’t need the auxilary encoder on RA. This is only used if you use the mount’s PPEC. And PPEC is incompatible with guiding.

Thanks WIM. I have turned off all the encoders, but the mount does not respond at all in RA to the Park command. Both in NINA and EQMOD.

Say I manually put the mount in the home position. Both RA and Dec are at the ZERO point on the setting circle.

I slew E, W, N & S etc, then click PARK.

The DEC axis returns to home position, but the RA does not respond. It stays wherever I slewed to?

Can I try imaging in spite of this? I am worried this is indicative of a problem?

You mentioned: Also reset any mount model in eqmod

What do you mean by that, and where can I do that?

[wimvb]

If the mount slews to any target and tracks that target, then there is nothing mechanically wrong, and any issue is in software. I am not that familiar with eqmod, but I know that you can have several options to set park position. As regarding pointing model, I assumed that this is similar to the eqmod driver in INDI. But you may want to check this.

[oymd]

1 hour ago, wimvb said:

If the mount slews to any target and tracks that target, then there is nothing mechanically wrong, and any issue is in software. I am not that familiar with eqmod, but I know that you can have several options to set park position. As regarding pointing model, I assumed that this is similar to the eqmod driver in INDI. But you may want to check this.

Perfect.

Yes, I missed the tickbox for DISABLE ENCODERS. Once I unticked that, everything went well.

Many thanks

P.S. It seems my the GODS will never allow me to take this out for a night of imaging!!

I loaded the Esprit and imaging train on the freshyly assembled mount. As I was tightening the two knobs on the VERY poor stock saddle, one of the knobs gave way, and would simply not tighten!!

Why is EVERYTHING going wrong for me...?

Anyways, I am very worried of leaving the Esprit on the mount with just ONE knob tightened. It seems the inner threads of the saddle stripped!!!

Are they M10 bolts?

[wimvb]

It seems to me that you need to make an offering to the astro gods. (Or buy a quality saddle from FLO.) I wouldn’t rely on just one bolt either, and if the saddle thread is stripped, replacing the bolt won’t help. I know that most astronomy dealers have saddles. Just make sure that it fits your mount. Btw, does your Esprit have a vixen or a losmandy dovetail bar? For a larger scope, a Losmandy seems more stable. On my 190MN I have replaced the standard vixen for a Losmandy

[oymd]

4 hours ago, wimvb said:

It seems to me that you need to make an offering to the astro gods. (Or buy a quality saddle from FLO.) I wouldn’t rely on just one bolt either, and if the saddle thread is stripped, replacing the bolt won’t help. I know that most astronomy dealers have saddles. Just make sure that it fits your mount. Btw, does your Esprit have a vixen or a losmandy dovetail bar? For a larger scope, a Losmandy seems more stable. On my 190MN I have replaced the standard vixen for a Losmandy

Hi Wim

Yes, I contacted FLO today. They do not have the ADM saddle in stock. The problem is, I am abroad!

I could not resist. I used the second bolt, and it give an OK grasp, but week. I zip tied the heck of the Esprit and its rings and clamps to the saddle, just for reassurance!

I am having a NIGHTMARE now with guiding.

Ran calibration. It was not happy! Says I have SEVERE DEC backlash.

This is confusing. If I have SEVERE DEC baclash, why is my DEC RMS 0.09 in PHD2, and the RA is almost 3.5RMS??!!

So, it seems RA issues continue.

I am now running Guiding Assistant, and will post results.

I am very confused about PHD2's interpratation.

BTW, I fine tuned the grub screws, and both DEC and RA are SOLID. No play at all? Why is there still significant backlash?

In the current setup, I am using the Esprit, with a 290MM Mini fitted to the 9x50 Skywatcher guidescope, at 181mm focal length.

Just before all of these issues started, I was regularly guiding with a TOTAL RMS of about 0.7RMS, but that was with the WO Star 71 fitted with the Sky Watcher Evoguide 50mmED and the smaller 120MM Mini.

I think I have grown a few years older this past week!!

[wimvb]

1 hour ago, oymd said:

Yes, I contacted FLO today. They do not have the ADM saddle in stock.

Teleskop Service in Germany may have Geoptik or Farpoint saddles in stock. Mind you, they’re not cheap.

If you can feel backlash, you’ve got way too much of it. When I tuned backlash on my mount, I spent an entire night with it. I started by measuring backlash with PHD guiding assistant. (I started with just less than 5000 ms.) Then I adjusted the grub screws less than 1/8 of a turn. Measured backlash; adjusted 1/16 of a turn, etc . This got it down to about 500ms, which is fine. With each adjustment I checked for binding. When binding occured, I backed off and started from the beginning, because there’s backlash in the backlash adjustment.

2 hours ago, oymd said:

think I have grown a few years older this past week!!

I know it’s frustrating. But you’ll get there.

[wimvb]

2 hours ago, oymd said:

This is confusing. If I have SEVERE DEC baclash, why is my DEC RMS 0.09 in PHD2, and the RA is almost 3.5RMS??!!

One more thought on this: tension in the belt. Run guiding with short (1 s) guide exposures. Analyse the guide graph in phd log viewer and do a frequency analysis. A 10 s period is an indication of a belt that is too loose. (You need short guide exposures to see the 10 s period.)

Unfortunately I can’t do the analysis, because I too am abroad atm. But only this week.

Btw, zip ties can possibly secure the scope, but they can’t fix it in place. And with a scope that isn’t rock solid fixed to the mount, troubleshooting will be almost impossible.

Edited January 18, 2022 by wimvb