zero backlash neq6 worm

[Mike M]

This was last week's guiding in a seeing of 3

 

Edited June 12, 2020 by Mike M

[spillage]

Have you tried running the PEC algorithm in PHD?

[mbalkham]

I'm using a ZWO 290MM Mini on and Orion ST80 (400mm fl). I've played with a range of guide exposure lenghts from 1-5s but it doesnt seem to make much difference.

Imaging at 1250mm on and Orion Optics UK CT10 (10" f5) and with ASI071MC Pro. Resolution of 0.824"/pix so hoping to guide at less than that (half ideally right?).

Pic before latest mount mod and with old guidecam.

[Mike M]

11 minutes ago, mbalkham said:

I'm using a ZWO 290MM Mini on and Orion ST80 (400mm fl). I've played with a range of guide exposure lenghts from 1-5s but it doesnt seem to make much difference.

Imaging at 1250mm on and Orion Optics UK CT10 (10" f5) and with ASI071MC Pro. Resolution of 0.824"/pix so hoping to guide at less than that (half ideally right?).

Pic before latest mount mod and with old guidecam.

Ok cool, yeah I went away from the short tube because I was getting horrible differential flexure, even with the Losmandy Dovetail and rings.  Temp drops where I'm at (-21s latitude in the Tropics) during winter can start out at 17c and quickly drop to single digits.  Your setup is almost the same as mine with the 10" F5 @ 1250mm except I'm GSO.  My image scale is a bit higher at 0.63" with the ASI1600MM Pro so some nights I have horrible stars if seeing is bad.  I'd be looking at the ZWO thin OAG as you'll be saving weight plus not have to worry about differential flexure.

Cheers, Mike

[Mike M]

Here's my setup.

Cheers, Mike

[bottletopburly]

If in doubt with anything ask @1parsec .

[newbie alert]

7 hours ago, mbalkham said:

Excuse the crying baby in the background!

That's play from the locking nut on the worm bearing, you can adjust it out but it means taking the mount apart..basically you have lateral play in the worm spindle..it's a really simple job with a tool like this

[mbalkham]

18 minutes ago, newbie alert said:

That's play from the locking nut on the worm bearing, you can adjust it out but it means taking the mount apart..basically you have lateral play in the worm spindle..it's a really simple job with a tool like this

It's def not play in the worm. It's the spring in the zero backlash moving. It's supposed to do this.

 

[mbalkham]

8 hours ago, Mike M said:

Ahh perfect thank you - that's exactly what mine is doing.  That makes me feel a lot better! I'll put the 10" on it during the weekend, balance it and give it a slew to make sure all is good.  We've got clouds and rain for the next 2 weeks so can't test for a while. 

I did manage a slight improvement tonight but it still 'bounces' under light load. I'm convinced it is the spring taking up the load doing what it is supposed to to eliminate backlash. I did remeasure the shims and adjust them so hoping for improvement next start night. Also paid more attention to tensioning everything up and adjusting the worms.

I also found you can test if it is the springs or a combination of some residual backlash or worm movement with the locking grubs and nuts that the instructions tell you to back off half a turn. If you tighten them up temporarily the play disappears confirming that it is spring movement. If there is any play with them tight then you have backlash or worm issues. remember to back them off though!

Edited June 12, 2020 by mbalkham

[newbie alert]

4 minutes ago, mbalkham said:

It's def not play in the worm. It's the spring in the zero backlash moving. It's supposed to do this.

 

Ok, I've not had any experience with this but if the locking nut isn't tight enough it would do the same thing as your video, which you will never dial out..which leads me to think why introduce play? 

[1parsec]

Hello All,

The movement in the video is completely normal and as expected.  That's the springs allowing the worm to move in and out of mesh.
However the adjustment screws should be adjusted to make this movement much less.
The amount of spring movement needed should be just enough to accommodate the eccentricity of the wheel gear.
The eccentricity of the wheel gear is usually no more then 0.2mm . So the adjustment screws (labelled B, last page in the instructions) should limit the direction of movement shown in the video to this sort of range. 
If any one needs further help or advice setting the ZB assembly, drop me an e-mail. E-mail address on our website.

[Mike M]

I just finished adjusting mine and everything is looking perfect.  It definitely sounds a bit quieter than before as well.  All new super lube on the gears, balanced perfectly and the DEC has next to no backlash.  Now all I need is some clear weather! I don't think we'll be getting anything anytime soon though.  

Here's a vid I uploaded to my page of it in operation - https://www.facebook.com/mackaystorms/videos/700962433812505/

Cheers, Mike

Edited June 13, 2020 by Mike M

[Mike M]

19 hours ago, 1parsec said:

Hello All,

The movement in the video is completely normal and as expected.  That's the springs allowing the worm to move in and out of mesh.
However the adjustment screws should be adjusted to make this movement much less.
The amount of spring movement needed should be just enough to accommodate the eccentricity of the wheel gear.
The eccentricity of the wheel gear is usually no more then 0.2mm . So the adjustment screws (labelled B, last page in the instructions) should limit the direction of movement shown in the video to this sort of range. 
If any one needs further help or advice setting the ZB assembly, drop me an e-mail. E-mail address on our website.

Yeah when I did a complete 360 slew on the RA I could not see a single bit of movement with the worm block.  I have the 2 adjustment screws set to half a turn and when I gently rock it back and forth it comes back to its home position perfectly.  

Cheers, Mike

[Mike M]

Hi all, has anyone had any clear skies to use their modded mount yet? If so how have you found it?

Cheers, Mike

[mbalkham]

I've had another go with it since the re-adjustment but didnt see much improvement (around 0.9"RMS). Polar Alignment was a little off and afterwards I found that I didnt tighten the counterweight arm locking nut (oops!). Hoping to get down towards 0.5-0.6"RMS with a little tinkering, good PA, balance and seeing! Rubbish weather for the foreseable so not much chance to try again.

Still waiting for this upgrade https://www.teleskop-express.de/shop/product_info.php/language/en/info/p3025_Counter-weight-bar-for-EQ6--chrome-plated--with-5-kgs-counter-weight.html to arrive (at least 4 weks away). That will stop me from leaving the locking nut undone!

Edited June 17, 2020 by mbalkham

[Mike M]

23 hours ago, mbalkham said:

I've had another go with it since the re-adjustment but didnt see much improvement (around 0.9"RMS). Polar Alignment was a little off and afterwards I found that I didnt tighten the counterweight arm locking nut (oops!). Hoping to get down towards 0.5-0.6"RMS with a little tinkering, good PA, balance and seeing! Rubbish weather for the foreseable so not much chance to try again.

Still waiting for this upgrade https://www.teleskop-express.de/shop/product_info.php/language/en/info/p3025_Counter-weight-bar-for-EQ6--chrome-plated--with-5-kgs-counter-weight.html to arrive (at least 4 weks away). That will stop me from leaving the locking nut undone!

Oh nice! something I might have to look at - the biggest issue I find with my counterweight bar is that because I use 4x5kg weights, the 4 grub screws are literally gouging out the soft aluminium from the weight and I am constantly doing them back up every few weeks.. We're finally due for clear skies Monday next week so will be able to get some imaging in then - I think tax time I might look at getting that counterweight bar if you have good success with it.

Cheers, Mike

[Mike M]

Got the first clear night in 2 weeks and just went to try it out - got a 4km/hr breeze and I'm not impressed, it's moving all over the place by around 10 pixels every time the breeze happens.  I could easily image with up to a 15km/hr breeze before hand, is there some more adjustments I need to do? I can't even take a 5s autofocus frame without it smearing the stars.  When there's no breeze at all it's perfect. My scope is in an observatory and only the top is sticking out as it's near the Meridian my target.  

Cheers, Mike

[bottletopburly]

1 hour ago, Mike M said:

Got the first clear night in 2 weeks and just went to try it out - got a 4km/hr breeze and I'm not impressed, it's moving all over the place by around 10 pixels every time the breeze happens.  I could easily image with up to a 15km/hr breeze before hand, is there some more adjustments I need to do? I can't even take a 5s autofocus frame without it smearing the stars.  When there's no breeze at all it's perfect. My scope is in an observatory and only the top is sticking out as it's near the Meridian my target.  

Cheers, Mike

Take @1parsec aka mr Rowan astronomy , advice  email him with your problem I’m sure he will be able to help and advise accordingly.

[Mike M]

16 hours ago, bottletopburly said:

Take @1parsec aka mr Rowan astronomy , advice  email him with your problem I’m sure he will be able to help and advise accordingly.

I ended up re adjusting the grub screws again, it seems a bit better now and not as easy to push with my finger so will give it another run tonight. I think I just gotta keep adjusting it until I get it 

Cheers, Mike

[Mike M]

Hi all here's an update - this is a 5 min luminance sub at 0 gain showing perfect circles. The only thing I have to fix now is sensor tilt, but looking good!

Cheers, Mike

[mbalkham]

Nice work Mike. I'll have another play with mine at some point. I tried last night but we had fog/low cloud so I gave up after a few hours. Feels like it should be better. What was your guiding looking like?

Edited June 22, 2020 by mbalkham

[mbalkham]

On your tilt question someone told me about the CCD inspector function in ASTAP. It looks at FWHM values across the frame and gives a value for tilt (and it plate solves really quickly). Might help you out. Plus it's free!

[Mike M]

1 hour ago, mbalkham said:

Nice work Mike. I'll have another play with mine at some point. I tried last night but we had fog/low cloud so I gave up after a few hours. Feels like it should be better. What was your guiding looking like?

Thanks mate! I was only getting a total of around 1" total because seeing was a whopping 4 arc seconds! Crazy.. tonight should be a lot better though. Here's my graph, I think I need to tweak phd's settings still because it's still oscillating a bit. I gotta remember too that I'm carrying a 1250mm scope which is still way too heavy for the neq6 Pro.

Cheers, Mike

[Mike M]

1 hour ago, mbalkham said:

On your tilt question someone told me about the CCD inspector function in ASTAP. It looks at FWHM values across the frame and gives a value for tilt (and it plate solves really quickly). Might help you out. Plus it's free!

Yeah I purchased CCD Inspector a few years back but only used it a handful of times.  What happened recently for my tilt though is I didn't have the brass compression ring in my moonlite focuser, so put it in and looks like my MPCC MKIII Coma Corrector doesn't sit squarely in the tube now. The MPCC's are renowned for not sitting nicely in the focuser tube. 

Cheers, Mike

[mbalkham]

39 minutes ago, Mike M said:

Thanks mate! I was only getting a total of around 1" total because seeing was a whopping 4 arc seconds! Crazy.. tonight should be a lot better though. Here's my graph, I think I need to tweak phd's settings still because it's still oscillating a bit. I gotta remember too that I'm carrying a 1250mm scope which is still way too heavy for the neq6 Pro.

Cheers, Mike

You've got to change your scale to 4" or even 2"! Looks super smooth though. I think the weight on mine is pushing me to look at a mount upgrade. Better start saving the $$$!