EQ6-R Pro Teardown

[bluesilver]

Sounds very odd indeed, as they shouldn't be tight at all.

Maybe put up a phot of what you have there,  sounds like either a very bad damaged thread or the casing itself could possibly be slightly damaged making the hole not so round,  but think both of these would be unlikely.

But if a hot air gun doesn't do the trick another option,  and might not be the best option,  but if you have a large container that it will fit in,  you could put it in there and then cover it completely with diesel, and leave it overnight. ( first remove the circuit board though )

Sounds odd i know,  but diesel is a great lubricant and have done this on other things that require freeing up.

But that little tool i made in the photo works well,  at the most you might bend the tabs on the tool to get it free,  but mainly it should only really be figure tight.

The first one it did was hard, but then with the second one i just gently eased the pressure on it and away it went.

 

 

Edited September 9, 2021 by bluesilver

[discardedastro]

11 hours ago, bluesilver said:

Sounds very odd indeed, as they shouldn't be tight at all.

Maybe put up a phot of what you have there,  sounds like either a very bad damaged thread or the casing itself could possibly be slightly damaged making the hole not so round,  but think both of these would be unlikely.

But if a hot air gun doesn't do the trick another option,  and might not be the best option,  but if you have a large container that it will fit in,  you could put it in there and then cover it completely with diesel, and leave it overnight. ( first remove the circuit board though )

Sounds odd i know,  but diesel is a great lubricant and have done this on other things that require freeing up.

But that little tool i made in the photo works well,  at the most you might bend the tabs on the tool to get it free,  but mainly it should only really be figure tight.

The first one it did was hard, but then with the second one i just gently eased the pressure on it and away it went.

 

 

Yep - sounds like I got very unlucky with assembly on this! There's always something.

I'm soaking everything in good penetrating lubricant. I suspect the answer is it was overtightened on assembly and the thread was damaged - so am hoping that once I get them out 3-4mm they'll come out the rest of the way without issue. I'll do some measurements once I get it all apart. If the threads were damaged I'll go ahead and re-grind them. Worst case, given there isn't much load on any of this, if I can get the old part out - by hook or by crook, and my "last resort" will be carefully cutting out a 1-2mm section with a Dremel through the port or taking it to a local machine shop to remove the old nut - then I can use the existing threads, a metal washer, and a 3D printed nut to adjust tension. Dimensional tolerances on professional 3D printing are plenty good enough for the coarse thread, and will accommodate a bit of play with damaged threads, and a spot of adhesive will hold it in place well enough once it's set without ruling out adjustment in future.

A good friend pointed out that Lucas used a similar slotted nut size for ignition switches for a while and so there are tools: https://www.holden.co.uk/p/lucas_switch_bezel_tools - exactly how similar we shall find out...

[bluesilver]

It will good to hear how you go with this,  can be frustrating i know.

But it will be worth the effort in the end,  Mine is back together and just waiting on clear nights,  You might have to play around a bit with the drive sprocket on the worm gears to get the belt to track correctly, but apart from that it should all go fairly smoothly form there on for you.

 

 

[discardedastro]

So the answer is - Rowan make a tool, just buy it! For £15 and next-day shipping, really can't fault it. Snug and perfectly fitting in the nut, felt completely secure even when leaning on it all.

https://www.rowanastronomy.com/productsa2.htm#neq6beltkit

It does exactly what you'd expect and worked a treat. I'd naturally been soaking everything in lube so once they got moving - which took a fair bit of force - they came out good as gold and the threads look fine.

Onwards!

[discardedastro]

So the mystery is revealed - after properly getting in and cleaning up the worm holders, there was an overabundance of pale blue threadlocking compound sat in the threads previously occupied by the slotted nut. Maybe Skywatcher went through a threadlock phase for worm end float adjustment nuts? I was planing to put a tiny amount in just to stop anything wandering but not quite that much!

Anyway, rest of the teardown has gone precisely as all the existing guides suggest it should - no surprises and nice and easy. The worms, bearings, and carriers are all out. I've cleaned up the carriers and deburred a whole bunch of edges, degreased everything thoroughly, took the rough edges off the flat surfaces with 1200 grit wet on a surface plate (barely ground anything off, but enough to give a nice finish), and everything now looks OK.

There's still quite a bit of dirt in the worms, so I'm going to drop them in the ultrasonic cleaner at work tomorrow along with the worm carriers and the pinions for good measure; I've also got a good stereomicroscope in the lab so will have a quick look at the worm and pinion surfaces for fun.

Then it's back on to reassembly! I've completely failed to find 0.5mm Teflon washers of the right size so the originals are going back in; I've opted for steel shims if I do need to adjust anything and have some 0.1, 0.2 and 0.3mm shim stock of the right dimensions for the big bearings from https://springfasteners.co.uk/.

[discardedastro]

Cleaned up everything and learned that the worm gears are mild steel or similar, not stainless or anything - left one in the ultrasonic cleaner (with fresh water) for a little while longer than ideal, and a thin black layer had formed with a small amount of rust pitting underneath when I returned. Will clean the other carefully by hand; have cleaned up the rusted one and there doesn't appear to be much if any lasting surface damage; I gave everything a good look under the microscope before and after cleaning and it looks fine. Surface finish isn't great, though - even on the one that didn't get a dunk. It's not terrible, but quite rough when you get in close.

I'm planning to very gently give everything some wet 1200 grit (finest I have) as best I can, and then will give it all a coat of corrosion inhibitor and then reassemble the carriers with usual EP lithium grease. Sadly I can't find anyone producing these, so not an option to replace or upgrade as far as I can see. More photos to come later!

[iantaylor2uk]

Sounds about right, usually the worms should be made of a softer material than the gear wheel that turns it (as you want any wear from running in to be on the worm, which is easier to replace). A lot of people use superlube with PTFE for regreasing.

[discardedastro]

I've not touched the worms in the end except to lube them (with Superlube PTFE). Here's hoping that'll be fine!

Sat down and did (most) of the rest today. Back to having taken some photos, too!

First, some essential tools, in retrospect. The first is self-explanatory and optional.

Next, the bearing retaining nut tool - note the hole in the top, you'll need a suitable bar or dowel to apply enough force if your nuts are properly stuck, but it's just the tool for the job and £15.

Lastly, the Knipex pin nut tool mentioned early in the thread - this is essential if you want to avoid mucking around with oil filter removal tools, works a treat, £50.

 

So - cleaning everything went fine except for the worms. Here's one of the pinions getting a bath.

This is one of the worms post-bath - note the rust in the well of the threads where some water lingered.

Carriers all got a careful clean (incl ultrasonic bath, because why not) after some deburring to get the worst offenders.

Worth noting all the grubs are M4 except the end nut securing grubs on the Dec axis which are M5.

As with every other fastener I could, grubs in the carriers were all swapped for some stainless steel ones.

This is the only bit I couldn't sort out as well as I'd have liked - the top bearing on the Dec axis wasn't budging and unfortunately the end nut is inset within the dovetail carrier mounting area so the Knipex nut tool won't loosen it. In the end I settled for cleaning this up as best I could to remove all the grease before applying some fresh stuff in the places I wanted grease and reassembling.

The good news is that following the Astro-Baby EQ6 guide, everything went back together exactly as you'd expect. Of note - you can leave the optical encoder off the RA axis worm drive and fit it through the opened electronics area without issue, so don't bother fitting that because you'll be wanting access to the nut behind the encoder plate to tune the worm meshing.

I think the only other thing I'd note was that it was much easier to fit both the top bearings for the RA axis (with washers between them) than fit the RA housing bearing to the base and then try to fit the inner surface on the RA motion stage. The tolerances on the outer surface are much more generous and make this task much simpler.

I used a lithium EP grease for all the bearing surfaces and packing the taper bearings (the others were pre-lubed and sealed) and bearing fitting, white synthetic lithium PTFE on all the other contact surfaces, copaslip on things like the clutch threads which are meant to move (somewhat), low-strength threadlock on anything that shouldn't move, and

So everything is now back together. I've not yet fitted the electronics board, the covers, or the alt/az bolts - I'm going to spend an evening or two fiddling with worm meshing, but it's already feeling pretty good. I'll power it up and see how it binds in a bit!

Edited September 25, 2021 by discardedastro

[discardedastro]

Just to round this thread out - it works after reassembly! I've not yet fiddled with it beyond making sure it's happy, balanced, and not binding - the way the clouds are going all I get to do tonight is basically this. However, it's looking quite good. Certainly not a regression, which was my main worry. Backlash looks OK, but can probably be improved a little for Dec with some careful fettling. Overall looking promising.

[discardedastro]

I've now run this for a while with some actual stars to look at, so I think I can call this a success, and figured I'd show my working to demonstrate the improvement.

Previously my guiding performance was limited to circa ~1" RMS in good conditions, such as the ~4h session shown below.

Post-upgrade that's fallen to circa ~0.5" RMS. Note that this graph is zoomed in to explore some detail. That's pretty consistent across a couple of nights of imaging now, so is a result I definitely think I can stand behind. I've not dug into any FFT analysis of the guide logs yet but there's nothing obvious glaring out - the peaks in the below graph are well aligned with dithering as expected and there's nothing significantly systematically wrong.

Is a 1" to 0.5" guiding improvement worth £200 in new bearings and a weekend of fiddling? Depends on your application, and for most, probably not. But it was a lot of fun, I now understand my mount much more, and I've undoubtedly increased the longevity of my mount overall, stored outside as it is. So I'll count this one as a success!

[Ali Alhawas]

Nice reference and useful details..

 discardedastro 

Could you take a look at this topic of mine..

 

Maybe you can help.

I am really stuck !

 

Thanks

[rrbailey89]

Not to necro this thread but I came across it in all of its glorious information while searching for a question to a potential problem I have. 

I am wondering what level of water resistance if any the EQ6-R Pro has. I was out a few nights ago now and the sprinklers kicked on in my neighborhood, these are automated some way and do not turn on at the same time each night, they dont even turn on every day and I have no control over them. Regardless the mount was set up and It got wet (it was not plugged in). I am more curious if there are seals that help keep water out of the mount head or if I should break it down and examine the inside.

[discardedastro]

1 hour ago, rrbailey89 said:

Not to necro this thread but I came across it in all of its glorious information while searching for a question to a potential problem I have. 

I am wondering what level of water resistance if any the EQ6-R Pro has. I was out a few nights ago now and the sprinklers kicked on in my neighborhood, these are automated some way and do not turn on at the same time each night, they dont even turn on every day and I have no control over them. Regardless the mount was set up and It got wet (it was not plugged in). I am more curious if there are seals that help keep water out of the mount head or if I should break it down and examine the inside.

There's no seals, I'm afraid - so if it got sprayed with water, the odds are good there's some in there. Most of it is brass and aluminium, which is good, but the worm gears are mild steel, and I wouldn't swear to the materials used in the bearings!

If it got a light spritz I would just dry it out - stick it in a closed box with some silica gel or similar (you can get silica gel in bulk). For reference mine lives outside, under a Telegizmos cover, in a wet bit of the UK with high humidity and lots of local water and is absolutely fine with it. If it got a good drenching I would at least pop the cover off the motor area and see if that looks dry.

[badhex]

I wrote this yesterday and realised it didn't post! Basically the same answer as @discardedastro

 

I don't know the answer for certain, particularly regarding the moving parts, but I believe there is very little in the way of waterproofing. Light dew or frost is probably not an issue but a blast from a sprinkler could be more serious. Some of the panels unscrew easily enough to have look if there is any ingress without having to completely dismantle it, and if there is you probably want to put it somewhere warmish and dry for a week or so depending how wet it got, before putting any power to it. 

[newbie alert]

Just picked up on this thread..

Don't assume that what was factory fitted should be reassembled in the same order.. synta fail to mesh the worms to the correct height, over tighten the locking nuts, lock up the worm bearings etc ... Doing what you are doing will improve things to a better standard as it should have left the factory in... White lithium is a slight improvement over that black gunk, but won't last as long as PTFE superlube

Edited November 9, 2022 by newbie alert
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