Skywatcher EQ6-R Mechanical Backlash Questions?

[TheButcher]

Hey all,

I have a 2 month old EQ6-R that seems to act up half the time with elongated stars and sometimes really trailed. Now these are all Guided with the Orion 50mm Delux and a 290mm. It happens with both my RC 8" and ED80. And I also hear some noises when it slews every now and then. And occasionally a crack or pop sound. My RMS numbers in PHD2 are not bad at all when I get these elongated stars, The RMS usually is around .75 on the average. And the highest is usually around 1. I also correct the elongated stars when I repark it or adjust the counterweights a little. So all this leads me to believe that something internal needs adjustment. Also to mention It started doing 10-12 minute exposure with out a problem when I first got it.

Here is my current config
AT8 8" RC
ZWO1600mm-p
ZWO EFW 8 Pos
Otion MIni Guide Cam (to center mounted) with 290mm(non mini version)

I checked balances and I tried with near perfect balance on all axis included the dec balancing each side.

Anyway to make a long story short.

What is the correct method of mechanically checking and adjsuting the backlash? Also the worm Gear And What do those Black circle covers do and what should I look for inside ect… I am pretty mechanicly inclined so not afraid of taking things apart. But with this mount I searched online and have not seen much of the EQ6-R partialy disassembled and necessary/recommended steps to do.

I took apart my AVX and did the old regrease with Superlube and adjusted the gears and that went well, so I want to go about opening this baby up and check the belt tension and such kind of like I did with the AVX.

I am open to all suggestions.

[TheButcher]

Here is an update on my progress if this helps anyone, but do it at your own risk. This post will just be one of the short videos that I did showing one of the issues I had. And the issue was the DEC belt tension. I had to take the front plate off of the Skywatcher EQ6-R pro first and gently loosen the DEC and RA Motor allen screws. Then went to the other side of the scope and opened up the belt drive lids.

I made 3 videos as I was doing this. I will explain more in detail as I also found a way on how to fix my other issues which was worm backlash on both the DEC and RA. This involved a different approach and I did not have to open anything up, just adjust some screws but I will explain that another day as I am getting ready for bed.

And remember to try this at your own risk, I am just showing what I did.

https://www.youtube.com/watch?v=Cr6tlgELf_8 Part 1

https://www.youtube.com/watch?v=bC153MpyNqU Part 2


https://www.youtube.com/watch?v=PIpQVjOkyLQ&t=2s Part 3

[yobbo89]

To you realy make the most of your mount one really needs to understand how to tune it, eccentric gears from machining is a problem on mass production. So usually you'll find one or few spots where the system binds due to this, to compensate this most mounts should come shiped a bit loose, yours might of not been adjusted enough and possible your climate conditions has effected it.

I typically i put the tight spot of the gear on the underside so it will never get used or depending where the worm is then lock down the clutch to never be used again then I tune the heck out of it.

I also use a indicator (used for machining lathes, mills ectt) and prob the end of the worm then wiggle the Ra or Dec axis.

Finding better tolerance bearings for the worm helps a bit too. Ideally manufactures should be using a conical shape bearing for the worm but they don't, they use the standard bearing seen in skateboard, Rollerblade wheels

[TheButcher]

Thanks Yobbo

When you mention "i put the tight spot of the gear on the underside so it will never get used or depending where the worm is then lock down the clutch to never be used again then I tune the heck out of it." Is that refering to the tiny allen screws on the outside of the mount and one set for the RA & DEC are on the top and the other on the bottom?

Here is a photo of the top with the tiny allen screws that I mentioned above.


Thanks,



Also here is a link I found on how I adjusted my worm gear backlash it is a PDF file from another forum. I did not know how to attach the PDF here so I just copied the link address.
https://stargazerslounge.com/applicatio ... ?id=321017

[yobbo89]

The worm belt isn't too hard to adjust ,just has to be firm and not sloppy, there's not much meshing in it due to it hugging the gear.even getting it a bit too tight shouldn't cause much of a problem . just yanking on it finger tight is enough, i think there is a rule of thumb, generally i would push on the middle of the belt and if it moves in 2-3 mm then that's enough slack .

[yobbo89]

those grub screws in your pic should be the back stop screws for the "worm'', the worm should be fixed so it just moves the head assembly backwards and forwards onto the shaft with the main gear cog

[yobbo89]

could you upload some audio or video of your mount slewing ? specifically at that spot that makes the noise you mentioned

[TheButcher]

Thanks again for the help

Sure no Problem, I wll take some video of it slewing with out a load and with a load of the OTA on it along with the weights. I'll post it when done on here, just got to move things around.

[yobbo89]

Thanks Yobbo

When you mention "i put the tight spot of the gear on the underside so it will never get used or depending where the worm is then lock down the clutch to never be used again then I tune the heck out of it." Is that refering to the tiny allen screws on the outside of the mount and one set for the RA & DEC are on the top and the other on the bottom?

Here is a photo of the top with the tiny allen screws that I mentioned above.


Thanks,



Also here is a link I found on how I adjusted my worm gear backlash it is a PDF file from another forum. I did not know how to attach the PDF here so I just copied the link address.
https://stargazerslounge.com/applicatio ... ?id=321017

just onto what i mean about the when i mention "the gear tight spot " . the main gear cog is a free floating brass piece that gets locked down with a clutch, the motor turns the worm via a belt and the worm turns this brass larger cog when the clutch is disengaged . so it is possible to find the high spot on the cog and then slew your mount and use your scope as reference to mark it, then slew the cog to a spot where your sky viewing doesn't need any location on that spot . if you get my drift, typical i would view/image 30 degrees above horizon ,so you can see that there is fair amount of the ra of the cog that doesn't get used , and it make sense to put this bad spot of the cog in a location that doesn't get used.

over the years i've really nailed down my tuning , it might be a bit difficult to understand without some diagrams ectt, this is something i've figured out and i don't think there any documentations online either.

i would probably skip this process i've mentioned and work only on the main gear cog and relieve some of that binding if you have any, i would only touch the worm to main gear adjustments for now .


here is a guide for the old eq6,i've linked it to just give you an idea on the push pull system on that grub screw, which i'm pretty sure is still the design for the new eq6 .

down the page with the gear brass gear cog

http://www.astro-baby.com/EQ6%20rebuild ... gnment.htm

[yobbo89]

My very very crude diagram, the cd is the Ra gear, the pen is the scope which I've made to look east and west, you can see if you put the bad spot of the gear cog on the opposite side of the worm that it dosn't get used. I don't know if it is Worth doing a guide on how to do this adjustmsnt, I don't think most astronomers are too obsessed with tuning there mount as I am

[TheButcher]

Thanks yobbo,
I took the videos and listed them below. And I will check out your diagrams and other info you just wrote now. And Thanks for helping

https://youtu.be/fCmIzCMijlU No Equipment

https://youtu.be/Jc8IFXnW0hM WIth All Equipment

[yobbo89]

it sounds like it is almost just right, when you stop the slew you get a chutter noise,this is an indication that it's tight but not binding tight. incorrect balance can upset a tight tuned mount to the point where it can stall . your mount sounds very healthy,and tuned , there is a tight spot i can hear in first video and it's most likely due to the balance, you shouldn't run a mount unbalanced .

can you send a video with the gear on the mount and wiggling the counter weight bar backwards and forwards by hand showing the end of the counterweight bar , this will show how much play you have on the axis, don't touch anything yet ! , your mount might be optimally adjusted and balance and poor skys might actually be your problem .

[TheButcher]

Yup no problem. I have been reading up on that info you sent too. I am understanding a lot better now. I gona go take the video and try to balance everything perfectly.

Thanks again

[TheButcher]

Here you go Yobbo,

Yo will notice my makeshift weight knob, I dropped one of the weights when carrying 2 on top of one another. They are slippery and I learned my lesson. Luckily the screw just bent slightly and the black knob cracked off so. I found a wing nut and dremeled it to make wider and epoxied it lol


There both the videos of the same thing just different angles and such.


https://www.youtube.com/watch?v=v3akVhtyETA

https://www.youtube.com/watch?v=KAMJwte38Qg


Thanks,

[yobbo89]

Very nice, your mount seems to be well adjusted from factory.

I would give it another go in tracking when sky's are good. Get a good balance and maybe try an offset on the weight to one side to load the mesh.



I've got a few busted eq6 knobs too, I'm going to find a set of these local

[TheButcher]

Thanks for all your help Yobbo

I can't wait to give it another go, next night looks to be this weekend.
And thanks for the link for those knobs, I need to get some as I don't see the black plastic they put on will last very long with me. I am just lucky that it got bent right after I am able to tighten it, if not I would of had to replace the screw bolt too.