Az -Eq6 strip down

[bottletopburly]

Graham Holmes doing a strip down on an AZ EQ6 , many will know graham may be helpful if your thinking of doing your own mount .

 

[Space Hopper]

Top man is Graham.

Highly recommended 👍🏼

[tich]

With the guiding errors mine is causing I may if I'm brave enough have a go.

[david_taurus83]

Looks completely different to the EQ6R. The AZ has needle bearings inserted into the cast housing. Not sure how easy these would be removed. I would imaging the worm bearings could be replaced easily enough though like the EQ6R. Didn't @Skipper Billy replace bearings on his mount a few years ago?

[Skipper Billy]

Its a pretty straightforward job - just take your time - photograph everything as it comes apart. Clean everything and use good quality lightweight grease.

There is a guide on my website - https://drive.google.com/file/d/1Gepzh1BL1M2oJCHEBoHVaOf-vWocMX7s/view

 

[david_taurus83]

5 minutes ago, Skipper Billy said:

Its a pretty straightforward job - just take your time - photograph everything as it comes apart. Clean everything and use good quality lightweight grease.

There is a guide on my website - https://drive.google.com/file/d/1Gepzh1BL1M2oJCHEBoHVaOf-vWocMX7s/view

 

Did you manage to take out the shaft bearings in the housing?

[Skipper Billy]

2 hours ago, david_taurus83 said:

Did you manage to take out the shaft bearings in the housing?

If I remember correctly - yes I did - it was a few years ago though!

[Ouroboros]

@bottletopburly  That’s a fascinating video. Thanks for posting that.  I watched it from start to finish. I’m not sure it’s scared me off or encouraged me to have a go. I’ve had my AZ-EQ6 for years now and a service probably wouldn’t go amiss. Although it still seems to work as it did at the start. I notice his mount spins freely in the Dec and RA axes. My mount has never been that free even when new, which makes balancing a somewhat hit and miss business. I also wasn’t aware of the backlash adjustment screws until watching the video. 

[bluesilver]

That is a great video on start to finish, wish i had that before i did mine.

I can't say that the nut on mine came undone that easily ( the one behind the polar scope ) I had to make up a long bar with a few pins to get mine to undo.

But after watching that i just remember that i hadn't done the bolts up after adjusting the backlash,  so a very good video just for that.

Something like this should become a permanent post, very helpful.

 

 

 

[Ouroboros]

Is there a similar video or description of how to adjust backlash?  Is that equivalent to the backlash as PhD removes during calibration?

[Bigwings]

Enjoyed watching and learned 1 important thing. I will send mine to a professional 

[wimvb]

Fyi, I just got guiding rms down from just below 1” to 0.5” (and down to 0.44”) by very carefully adjusting dec backlash. Previously I had improved RA by adjusting the belt tension. Just saying that a lot can be done to improve tracking without the need to disassemble the mount. But if you do need to take your mount apart, it’s good to have a guide like this.

[oymd]

On 16/09/2021 at 16:03, wimvb said:

Fyi, I just got guiding rms down from just below 1” to 0.5” (and down to 0.44”) by very carefully adjusting dec backlash. Previously I had improved RA by adjusting the belt tension. Just saying that a lot can be done to improve tracking without the need to disassemble the mount. But if you do need to take your mount apart, it’s good to have a guide like this.

Can you please share the details on what you did to minimise backlash on your mount?

I have a similar mount to the one above in the video. It’s fairly new, just a year old. 
 

I too have significant wobble on the Dec, and minimal wobble on the RA. 

I can’t see myself tearing the mount down as on good nights I average rms of 0.7-0.9. 
 

I read somewhere that the backlash on RA and DEC can be eliminated WITHOUT opening the mount, by just using a 2mm Allen key through the two tiny grub screw holes on either side of the DEC and RA axis on the mount?

is that possible?

[bottletopburly]

4 minutes ago, oymd said:

Can you please share the details on what you did to minimise backlash on your mount?

I have a similar mount to the one above in the video. It’s fairly new, just a year old. 
 

I too have significant wobble on the Dec, and minimal wobble on the RA. 

I can’t see myself tearing the mount down as on good nights I average rms of 0.7-0.9. 
 

I read somewhere that the backlash on RA and DEC can be eliminated WITHOUT opening the mount, by just using a 2mm Allen key through the two tiny grub screw holes on either side of the DEC and RA axis on the mount?

is that possible?

1.11 into video shows graham tweaking these grub screws , drop graham a message I’m sure he can explain more.

[wimvb]

1 hour ago, oymd said:

Can you please share the details on what you did to minimise backlash on your mount?

I have a similar mount to the one above in the video. It’s fairly new, just a year old. 
 

I too have significant wobble on the Dec, and minimal wobble on the RA. 

I can’t see myself tearing the mount down as on good nights I average rms of 0.7-0.9. 
 

I read somewhere that the backlash on RA and DEC can be eliminated WITHOUT opening the mount, by just using a 2mm Allen key through the two tiny grub screw holes on either side of the DEC and RA axis on the mount?

is that possible?

This is what I wrote on the Facebook group for EQ6 owners:

 I managed to get the backlash down  from 4000+ ms to about 1300 ms. As it may be of interest to others, here's a description of what I did:

1. Point the telescope just east of the meridian and just north of the celestial equator.

2. Calibrate guiding, guide for about a minute just to stabelise the tracking, apply guiding assistant and measured backlash.

3. Park the scope (pointing north) and loosen the South grub screw. Tighten the North grubscrew about 1/32 of a turn.

Repeat steps 1 - 3.

When I tried to get backlash below 1000 ms, the gears started to bind. Just backing off a tiny bit, didn't really improve things. I also found that it's important to tighten everything in the right order. Tightening the South grub screw before tightening the allen screws that keep the DEC in place, changes the gear meshing just a tiny bit. Enough to change backlash. So I always tightened the allen screws first, before I tightened the South grub screw. I think there's also some hysteresis in the mechanics, and when the gears start to bind, it may be easier to loosen everything and start over, rather than trying to go back in small adjustments.

 

 

And some time later:

A final update:

Tonight is a clear night after several days of rain, but with poor seeing. I opened my observatory to continue tuning backlash. Last time I tuned backlash too far and the mount started to bind. So I backed off a bit before closing up, expecting to have to repeat the entire exercise. But, lo and behold, without any adjustments, guiding assistant measured 248 ms (!). I let it guide for a while and ran guiding assistant again: 314 ms. I'm very happy with that. I will check backlash again when the air is more stable, but for now I'm very happy with this result.

 

Note: the 248 ms and 314 ms backlash was measured at a guiding rate of 0.8 x sidereal. when I measured backlash a few days after I wrote this post, I did so at my normal guiding rate of 0.5 x sidereal, and it was 700 ms.

This image is from during the first night of adjustments

This image is after the last adjustments

 

Btw, if you can feel a wobble in DEC or RA, your backlash is way off. At 4000 ms backlash, I couldn't feel it when I tried to move the axis by hand.

 

Edit:

One more thing you can do: Guide for at least half an hour. Don't change any settings. After that, download the guide log from PHD and look at it in PHD log viewer. Do a frequency analysis of the RA errors. 

This is the kind of graph I mean:

The peak at 480 s is the main period of the worm gear. The 120 s peak is from the RA pulley on the worm side. The very small peak at 10 s is from the RA motor pulley. If you have a high peak here, it will be very difficult to guide out, and you will need to adjust the pulley. All the other peaks will be guided out without any problem. I had this problem two years ago and had to tighten the RA belt. That solved it.

Edited September 19, 2021 by wimvb

[david_taurus83]

10 minutes ago, oymd said:

Can you please share the details on what you did to minimise backlash on your mount?

I have a similar mount to the one above in the video. It’s fairly new, just a year old. 
 

I too have significant wobble on the Dec, and minimal wobble on the RA. 

I can’t see myself tearing the mount down as on good nights I average rms of 0.7-0.9. 
 

I read somewhere that the backlash on RA and DEC can be eliminated WITHOUT opening the mount, by just using a 2mm Allen key through the two tiny grub screw holes on either side of the DEC and RA axis on the mount?

is that possible?

My first AZEQ6 developed play in the RA axis after about 6 months or so. I used the astrobaby guide to adjust out the backlash. The guide shows an EQ6 but its essentially the same process. I didn't need to touch the end float. Only the grub screws. It's important to check for binding after each adjustment.

https://www.astro-baby.com/EQ6 rebuild guide/EQ6 worm alignment.htm

[oymd]

Thank you for your rep[lies.

I will proceed with the above advice, but need to check a few points in my mount's anatomy, just to avoid messing up things:

 

@wimvb 

1- You mentioned: TWO different screws: Grub & Allen. By grub screws, are we talking about the tiny black holes on North & South sides of both DEC & RA axis? FOUR in total? If yes, then what are you referring to when you say: ALLEN screws? You did not reference the ALLEN screws in your steps 1-3? You only mentioned playing with the GRUB screws?

2- In step 2 you mentioned "apply guiding assistant and measured backlash"? What is that? Never did it? Is that in PHD2?

3- By calibrate in PHD2, I suppose you mean clicking SHIFT calibrate? I struggle always with calibration in PHD2 as it wants me to point somewhere at or below 20 degrees DEC, which is practically my horizon or even below!

 

@david_taurus83

You mentioned that the EQ6 strip down guides apply to my AZ-EQ6 Pro, but I recall seeing that the AZ mount has the freedom encoders, which make a significant difference in the strip down? Not sure.

 

I have attached a pic of my mount showing MY understanding of the GRUB screws and POSSIBLY the ALLEN screws you meant, but not sure??

There are 4 Allen screws on my RA body, but which Allen screws should I look at on my DEC?

Many thanks

 

 

 

[david_taurus83]

6 minutes ago, oymd said:

@david_taurus83

You mentioned that the EQ6 strip down guides apply to my AZ-EQ6 Pro, but I recall seeing that the AZ mount has the freedom encoders, which make a significant difference in the strip down? Not sure.

 

I have attached a pic of my mount showing MY understanding of the GRUB screws and POSSIBLY the ALLEN screws you meant, but not sure??

There are 4 Allen screws on my RA body, but which Allen screws should I look at on my DEC?

Many thanks

 

 

 

The guide I linked to is only to reference how to adjust the mesh between the worm and main gear. Also to check if the end float on the worm isn't loose. You don't need to strip the mount down to do this. Thats why the grub screws are there, to adjust externally. 

[david_taurus83]

You loosen the 4 allen bolts circled below, adjust the grub screws (arrowed) as per the guide, retighten the allen bolts and check for play. If your happy that removed the free play, start the check for binding. Readjust if necessary. As wim says though, you can only do so much by feeling by hand but it should improve things a lot.

[wimvb]

52 minutes ago, oymd said:

By grub screws, are we talking about the tiny black holes on North & South sides of both DEC & RA axis? FOUR in total?

Correct. These screws push the RA and DEC blocks where the worm gear is housed.

54 minutes ago, oymd said:

If yes, then what are you referring to when you say: ALLEN screws?

These lock the RA and DEC block in place. They are much larger and you see them clearly (4 per axis).

[wimvb]

55 minutes ago, oymd said:

In step 2 you mentioned "apply guiding assistant and measured backlash"? What is that? Never did it? Is that in PHD2?

Guiding Assistant is under the Tools menu in PHD2. You should run it at least once when you start a new profile,and every time you make a mechanical change in your setup. It will show you polar alignment error, settings for minimum movement (minmo) and measure backlash. MinMo is a setting that will depend on mount mechanics as well as seeing conditions.

 

[wimvb]

1 hour ago, oymd said:

By calibrate in PHD2, I suppose you mean clicking SHIFT calibrate? I struggle always with calibration in PHD2 as it wants me to point somewhere at or below 20 degrees DEC, which is practically my horizon or even below!

Yes. You can apply calibration at any declination, but PHD doesn't like it to be too high. There is a difference between DEC and Altitude. DEC is a number of degrees north of the celestial equator. Altitude is the number or degrees above the horizon. For me at 60 degrees latitude, the celestial equator is at an altitude of 30 degrees above the horizon (due south). This is also DEC 0 degrees. You can safely do your calibration some 10 - 15 degrees north of the celestial equator (for me this is an altitude of 40 - 45 degrees, when looking South). This may even be better, because if you calibrate too low (above your local Southern horizon), you well get a larger effect of the atmosphere and more seeing related problems.

Below your horizon sounds strange. in the Northern hemisphere, the altitude (degrees above the horizon) is always

(90 - your Latitude) + DEC

As I wrote before: for me an object is at altitude 30 + DEC, because I live at a Latitude of 60 degrees. If you live at a Latitude of 50 degrees, the altitude of an object is 40 + DEC. Normally you calibrate at or close to DEC = 0 (the celestial equator), which is at a local altitude of 90 - your Latitude.

Objects with a Declination (DEC) that is higher than your Altitude, are always North. Zenith (pointing straight up) has a declination which is equal to your local Latitude.

According to your Avatar information, you are located in or near London, which is at a latitude of 51 - 52 degrees. So, you would do your PHD calibration at an altitude of 38 - 39 degrees above the horizon. If you have bad local atmospheric conditions, you can calibrate at 45 - 50 degrees altitude, which is at a declination of 6 - 12 degrees.

Edited September 19, 2021 by wimvb

[oymd]

6 hours ago, david_taurus83 said:

You loosen the 4 allen bolts circled below, adjust the grub screws (arrowed) as per the guide, retighten the allen bolts and check for play. If your happy that removed the free play, start the check for binding. Readjust if necessary. As wim says though, you can only do so much by feeling by hand but it should improve things a lot.

Thank you so much for that. RA is clear. 
 

Sorry to be an absolute pain, but can you point out the 4 DEC Allen screws as well? 
 

And should I start with DEC then RA, or it doesn’t matter?

Lastly, when adjusting the grub screws and checking for binding, should I remove the scope etc from the mount, or do everything with the mount LOADED with the gear?

Many many thanks

 🙏 

 

 

[wimvb]

1 minute ago, oymd said:

Sorry to be an absolute pain, but can you point out the 4 DEC Allen screws as well? 

They are the top screws in your own image, and indicated in @david_taurus83 first image

[oymd]

5 hours ago, wimvb said:

Yes. You can apply calibration at any declination, but PHD doesn't like it to be too high. There is a difference between DEC and Altitude. DEC is a number of degrees north of the celestial equator. Altitude is the number or degrees above the horizon. For me at 60 degrees latitude, the celestial equator is at an altitude of 30 degrees above the horizon (due south). This is also DEC 0 degrees. You can safely do your calibration some 10 - 15 degrees north of the celestial equator (for me this is an altitude of 40 - 45 degrees, when looking South). This may even be better, because if you calibrate too low (above your local Southern horizon), you well get a larger effect of the atmosphere and more seeing related problems.

Below your horizon sounds strange. in the Northern hemisphere, the altitude (degrees above the horizon) is always

(90 - your Latitude) + DEC

As I wrote before: for me an object is at altitude 30 + DEC, because I live at a Latitude of 60 degrees. If you live at a Latitude of 50 degrees, the altitude of an object is 40 + DEC. Normally you calibrate at or close to DEC = 0 (the celestial equator), which is at a local altitude of 90 - your Latitude.

Objects with a Declination (DEC) that is higher than your Altitude, are always North. Zenith (pointing straight up) has a declination which is equal to your local Latitude.

According to your Avatar information, you are located in or near London, which is at a latitude of 51 - 52 degrees. So, you would do your PHD calibration at an altitude of 38 - 39 degrees above the horizon. If you have bad local atmospheric conditions, you can calibrate at 45 - 50 degrees altitude, which is at a declination of 6 - 12 degrees.

wow, what a super informative post. 
 

The way I check for DEC is by reading the numbers when I am pointing at an object in Stellarium. Even when I am pointing the scope really low, just above the hedge in my back garden, the DEC reading on Stellarium of whatever object I am pointing at is around 50 or so. 
 

I must admit I think I don’t get DEC reading right. Stellarium shows many DEC reading and I think I’m confused about it.