mbalkham

32 minutes ago, rnobleeddy said:

Can anyone with a beltmod on an HEQ5/EQ6 let me know if it improved dither times?

I've gone for RA + DEC dithering. This seems to work well in that the mount is stable, however, dithering takes about 50s to complete. This isn't the end of the world if I'm exposing for 300s as it's a lot faster than darks, but it'd clearly be better not to lose so much time. 

My guess is that the backlash in the DEC axis means it takes a long time to move and settle down, but the only other experience I have was an EQ5 where I set it to dither in RA only.

My belt modded NEQ6 dithers quickly (I haven't measured but I'd guess maybe less than 10 seconds). I'm not sure it's down to the belt though. Sounds like some other setting/issue? I have settle of 1s set after the dither. In the attached image I have taken 6 120s images and 6 dithers in about 12.5 mins so def less than your 50s dithers maybe 5-10s per dither.

Have you changed the amount of dither from the defaults? Mine are just default values (I forget what they are and aren't in front of that computer at the moment). I guess backlash could mean it takes longer to move the required amount of dither but it's moving a number of (or fraction of) a pixel so not like a lot of movement needs to occur. 

Are you running the guiding and dithering over a wifi connection or locally? If it's waiting to confirm receive info to confirm the dither movement it might take a little longer? 

Finally got everything working how it should. Re-tweeked gear meshing, re-distributed weight on OTA and improved balance. Now running the NEQ6 at 0.3-0.5" RMS with over 20kg OTA and 20kg counterweight. ZWO OAG also helping i think. 

Just now, astrosathya said:

the parameters seem to be almost the same. the guiding exposure was 3s to beat the seeing which is usually 1.5".  I am myself finding it hard to digest.

Suggest you look at pixel resolution. Maybe the guidescope focal length is incorrect in one set of guiding. Iwould think this amount of change is unlikely to be down to the belt mod.

12 minutes ago, astrosathya said:

Recently I had belt modded my HEQ5-PRO and last night i gave it a full run and i was absolutely stunned to say the least about the guiding results I achieved. I was left wondering if its even too good to be true! 
Below are Before and After images of guiding.

Something funny going on with these results. Error in pixels about the same top and bottom (0.27-0.24). Looks like something else has changed?

I've belt modded my NEQ6 and seen a slight improvement but I doubt you'll see much if you are already at 0.8"RMS. Maybe 0.1" if you're lucky but seeing, balance, PA etc. will affect things more than that. Belt mod def helps with backlash and runs a bit quieter.

I've also added zero backlash mod also from Rowan but yet to get the best from that (still needs tinkering). And I have replaced bearings, hypertuned, and upgraded other components.

Worth saying I am really pushing the weight on my mount (over 20kg of imaging and 20kg of counterweight) and am seeing typically tracking between 0.6" and 1" RMS.

On 22/08/2020 at 06:22, michael8554 said:

Roughly speaking there are three shapes of stars due to guiding:

Small round stars, fat round stars, and elongated stars.

So if you want small round stars you'll have to work on your guiding.

RA RMS is 50% to 70% higher than Dec, which means elongated stars.

I was in the elongated stars situation.

Best RA I could consistently get with OAG was below 1arcsec at 1280mm focal length, , but Dec was even lower, so I set a small drift in PA and set Dec Min Mo to up the Dec RMS to match RA.

Michael

There's a sneaky trick. Very clever, I might play with this at some point if I can't get RA and Dec closer to one another my some mechanical means.

Just got my OAG and redistributed some weight onboard for better balance either side of the flip. Moved the computer/power etc. on top rather than on the side so much closer to 50/50 weight distribution now.

6 hours ago, blinky said:

I would also say, are you getting nice round stars?  If so, then LEAVE IT ALONE!!!

Good frames are round bad ones are very stretched in RA (maybe twice as long in RA compared to Dec).

Thanks all for the tips. Next clear night I'll give a few a go. 

Looking at OAG which could help me plus save some weight. Failing that might look at new guidescope rings. Prob move the onboard rpi and dew heater for better balance. Going to fiddle with ra meshing again. Try shorter guide lengths. Sort a couple of cables. Check balance with ammeter. Plus a couple of other things!

4hrs of guiding 

Hi All,

Doing some analysis of last nights guiding (the best I've achieved). Around 0.9" RMS over 5 hours and best period under 0.6"RMS with 20kg of OTA (and 20kg of counterweight). Heavily modded NEQ6 mount (wedge, Rowan Belt, Zero Backlash mod, ceramic bearings, hypertune, new SKF bearings throughout (yes they made a difference and yes I know they only rotate once a day!), many Geoptik mount upgrades for stability). 

I know that the 10.2, 122.2 & 478.7 periods relate to stepper gear tooth, stepper gear and worm drive gear (from EQMOD Appendix http://eq-mod.sourceforge.net/docs/PECPrep.pdf). Can anyone point me to information on the effect of the belt mod on these periods? Just looking to see if there is anymore I can do to improve tracking. RA still looks a little erratic. 

Guidelog, frequency analysis and sample guiding attached.

PHD2_GuideLog_2020-08-17_185448.txt

Think I might have sorted it. RA belt needed a bit of tension. I also rebalanced. Guiding back to 0.8-0.9 RMS.

Struggling tonight on RA. Still think this is a setup issue. RA is normally half this error. Any ideas?

10 minutes ago, Mike M said:

Hi all, finally finished the image - here's the results of the upgrade, everything looks good and the mount is behaving perfectly.  Can't complain with how it's all looking now  - https://www.astrobin.com/full/2ttqs5/0/?real=&mod=

Nice work Mike. Clouds for 2 weeks here so haven't been able to test my latest tweeks, maybe this weekend. My Goldfocus has turned up to help tripple check my colimation (also use glatter and catseye!).   

35 minutes ago, Merlin66 said:

Not sure about the “spring” reference. I haven’t seen one on an NEQ6PRO mount.

 

This zero backlash mod mounts the worm gear on a 'spring' to keep contact without east heavy balance. 

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 $$$!

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!

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?

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!

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!

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.

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.

I wish i got down to 0.5-0.7". I'm nearly there now. I did the belt mod, bearings superlube but am still some way off. Any tips?!

1) before belt mod 1.25"RMS

2) After Bet mod ~1"RMS

3) After zero backlash 0.9"RMS

Excuse the crying baby in the background!

Yes mine moves as you describe. I cant adjust it out. I figured it was supposed to have some movement as the spring compresses? Tightening the 5 locking screws that attach the mechansism to the casing did help a little.

I've installed this mod today and preliminary results are showing a slight improvement but not quite what I was hoping for right out the box. Needs a little more tinkering. Well built and install was pretty straightforward. Adjustment not as easy as the instructions would have you believe and still rely on feel. Not sure if I'm expecting too much under the load I have on it (20kgs of OTA and 15kg counterbalance!). Will try under less load another night. 

Also waiting for Geoptik counterweight upgrade to stiffen that connection.