Question before I start my EQ6 Hypertune

[mldee]

I've been reading all the threads and googling my heart out in preparation for The Big Event. The rattles from the motors and the slight looseness in my EQ6, much less the eggy stars, pursuade me that a tune up is advisable, plus at least I then have a known good item to remove from the list of potential image problem sources.

I have gotten good advice, parts and assistance from Peter 4059, Allan and others, thanks guys, and I've collected all the other bits and pieces necessary, except the six large bearings, which in total cost about $180 for SKF brand. I don't mind paying this amount, but I would like to feel that it was money well spent and not just "hobbyist overkill", as there are other factors that come into it, which are the root of my indecision.

Obviously the total worm gear setup is top priority for tuneup. including new ceramic bearings, etc, plus cleaning, paint & swarf removal, re-lube, clearances, etc.

My question is: Will replacement of all or some of these six larger bearings really achieve anything worthwhile for a "happy snaps" imager such as myself? The other larger bearings simply support the RA and DEC shafts in rotation, and two more taper roller bearings provide end-thrust support for the shafts. All of these bearings rotate at far less than 1rpm, and max load is in the small tens of Kg. Considering the size of these bearings, quite trivial, one would think. They're the size of car axle bearings! Naturally they need to be checked for cleanliness and good grease during the tune up. I bought some Nulon "Lithium + PTFE" grease at Supercheap which I plan on using.

Removal and replacement of these bearings may involve some effort and need for bearing pullers, etc if they are a tight fit. These additional tasks, needing to be done without assistance, plus the potential to screw something up, are the main reasons why I am tempted to "leave well enough alone" in this area.

The flip side, of course, is that if the final Hypertune result doesn't make much difference anyway to my imaging, one may always be thinking "should have replaced those damn bearings when I had it open!".

So...open for comments. (The major factor for Brissy folks is that the longer I have it open on the workbench, the more clear skies everyone else will get :)

[Moon]

Mike,
It would be good to measure the PE before and after and see if you can improve it.
Are you going to replace the worm or just the bearings? I think this is the key part to focus on.
If you enjoy tinkering, then go for it. Just be careful you don't break anything.
James

[bojan]

Before you start..
Do you have the PE plot of your mount as it is now?

[mldee]

Bojan - Nope, never got that far down the track :). I'll do one today though. Certainly makes sense to have a before and after.

Having said that, how much effect on PE do those main bearings have, presuming they're in reasonable condition as is?

James - As to Worm work, my basic plan is to change the bearings, clean & lube the worm assembly, check transfer movement and clearance, and of course adjust wormdrive backlash.

[bojan]

Well, in my case (EQ6 classic) I had (and still have) a problem with transfer gears (47-teeth each.. http://www.iceinspace.com.au/forum/showthread.php?t=43823&highlight=Eq6+belt+modification (http://www.iceinspace.com.au/forum/showthread.php?t=43823&highlight=EQ6+mod)), which are causing 3-5 arcsec "noise" superimposed on the general PE curve (caused by worm gear and meshing). This is going to be reduced by timing belt & pulleys (already in the queue, just need some spare time for this)
I don't think my mount has any other issues that can't be sorted out by autoguider.
So, before you start, you have to know exactly where your eventual problems are (if there are any). Otherwise, the whole exercise could turn into expensive affair, with a lots of hopes and not much gain...

Try to use k3ccdtools, it will produce a plot of your mount PE, from where you will see what is going on and how bad it is (http://www.pk3.org/Astro/index.htm).

And, yes, only tapered bearings (and those 2 on RA worm) are important.. the others do not turn at all during tracking, so I would not consider them for replacement at all.

[peter_4059]

Mike,

I think you'll find all the bearings on the RA axis turn during tracking and two on the Dec axis are stationary when the dec clutch is locked.

The noise you are hearing is most likely coming from the transfer gear between the motor gear and the spur gear. You will probably find this is too loose and needs the retaining bolt tightened up a bit.

If you are intending to lubricate the main bearings you will probably need to remove them from the mount to clean them out and there is a good chance you will damage the bearing seals when you try to remove them.

You can use PERECORDER to measure the PE. Have a look on the EQMOD/EQ6 yahoo group.

Pete.

[asimov]

Having stripped & inspected every moving part on my EQ6 a few times now, I have seen absolutely no reason to replace any bearings. If there is no play of any descripion in a bearing there is no point in replacing it.

The only 2 problems you will find is A: The bearings will not be packed with grease effectively, causing problems later on in life for the bearing.

The other problem is imprecise preload adjustments of these bearings from the factory.

Simply repacking the bearings, correctly adjusting the bearing preloads & doing the worm to gear clearance should really be sufficient. Bearings in slow moving EQ mounts should, & will last a long time as long as one plays it smart. Playing it smart comprises NOT thinking the worker at the factory has put the thing together within suitable tolerances lol.

Just my opinon based on the facts presented before me on my particular EQ6 specimen.

[mldee]

Thanks Pete and John for your comments. I'm leaning towards a "suck it and see" approach, meaning I'll take a look at the goop inside the main housing and if it's lousy or has metal bits in it, I'll probably replace at least the RA and Thrust bearings if it looks like I'd damage the seals during removal for cleaning.

If the internals of the casing look reasonable, I'll leave them be and concentrate on the worm section.

One small question, and I think you told me this already Pete, are the two taper roller thrust bearings easy to remove and it's the ball bearings that need the persuader, or vice versa? I would suspect the taper bearings should be easy to remove and clean/regrease, whereas the ball bearings would have the dirt seal on both sides and would be a tight fit on the shafts as well. Am I correct?

[asimov]

I know I was worried about getting mine apart - bearings stuck in housings; bearings stuck on shafts scenerio. Mine just basically fell apart in the end, but your mileage will vary no doubt. A lot depends on the mount's age I'd say.

Good luck with it all, & all you can do is whatever necessitates doing.

[bojan]

Yep, I think you are right.. I mixed up shafts..

Still, I do not think there is a general need to replace any of bearings .
The main problem in EQ6 are transfer gears... and worm meshing to some extent.

The smooth PE curve is not a problem, and it can't be totally removed anyway.. it can only be reduced somewhat by adequate meshing (and that operation does not require dismantling of the mount).

[peter_4059]

Mike,

I found the taper bearings came out quite easily however the 6008 bearings were more difficult and required a tool to re-insert some of them.

As the 6008 bearings are all sealed it is likely these won't be contaminated with metal shavings however the taper bearings are not sealed and in my case had bits of aluminium from the housing machining process mixed up in the bearing grease.

As I mentioned earlier I decided to replace all the bearings because I didn't want to have to pull the mount apart twice. If your 6008 bearings were in good condition when they were installed at the factory then there is probably no need to replace them. The trouble is how do you determine what condition they are in without inspecting them? If you remove them from the mount to inspect it is likely you will damage the seals.


Peter

[asimov]

Once you've taken the dust seals out they will be beyond repair (usually) but who cares about the seals once they're out of the bearings? Toss them out. The unit is dust proof once closed up again.

[mldee]

That also was one of my suspicions :)

I went to the local mechanical supplies place today to check bearings availability, they had one out of the 2 rollers and none of the ball type, so I have to call the local bearing shop (Duh!) tomorrow.

I feel the "let's get started" juices starting to flow!

Now that I've sucessfully cleaned the QHY8 Pro sensor, the TEC control has become cantankerous ( USB/Driver problem I think, as the pic side of things is still good, just wants to go to full cold all the time). So I'll give it a rest and attack something nice and clunky mechanical instead.

[asimov]

This might come in handy if you haven't seen it before: http://www.astro-baby.com/EQ6%20rebuild%20guide/EQ6%20Strip%20Down%20Home.htm

Go for it!:thumbsup:

[mldee]

Thanks John. I had bookmarked this during my studies, but good to get a reminder. Time to print it out.

The forecast tonight said the cloud is starting to clear, so if I get stuck into it this weekend, should be some nice imaging time for everyone else :)

[asimov]

It's a good tutorial to follow, however some of the info. is not quite correct, or 'lines up' with my instances of stripping this mount. Still a great article to be used as a guide though.