Sorting out my old EQ6 Help requested

[powerlord]

Hi chaps,

Some of you might remember my moaning about about buying a 'great condition' EQ6 off someone (not this forum), only to find it was royally humped. I eventually fitted the rowan belt kit it came with, as well as totally stripping and rebuilding it:

Well, to be honest it's still far from right. I sits next to my 6 month old EQ6r-pro, and on the same target last night, with similar weights of kit the EQ6r-pro is ticking along getting 0.4rms, and this one is sometimes lucky to get 3rms. the RA is especially rubbish.

I've fiddled with removing backlash, and I've tried ensuring belts are tight but not too tight.. and none of it is making a difference.

So, my next plan before giving up and flogging it cheap as a doerupper to someone with full disclosure, is to disassemble it and rebuild it again - I'm wondering if I tightened something too much or put some of the teflon spacers in the wrong place or something. Though there are guides online, none are perfect, none show exactly where spacer go, etc - and maybe they depend on how many are required to bring something into line ? And at one point when I removed a shaft some of the teflon spacers fell off leaving me having to decide where they go back on again..maybe I've got that wrong.

So before I go there, I thought I'd ask people for first hand experience ? Last time, I cleaned and stripped off all old grease, replacing with superlube (though next time I reckon I'll just use a simple lithium or moly tbh), and everything did seem in good condition other than the hacked up hex bolts, screw heads, etc from the last idiot owner (couldn't even MOVE the alt as he'd tighened the bolts on the axis so much it wouldn't move - then stripped the threads of the adjustment bolts trying to force it to move!!!!) . No scars on the barrels, damage to teeth, etc. So I see no reason why this shouldn't be able to guide at least in the 0.6rms area.

Basically any tips , gotchas, things to watch for, etc greatly appreciated. IF someone has specific part numbers for replacement bearings that would also be great, as I imagine replacing the thrust bearing, etc with a decent quality one would be pretty cheap and I'm of the school of thought for jobs like this, if you are taking it all apart and can easily and cheapily replace bits, you should do it - same as if I'm working on an engine or hot tub, or boiler (to name the last 3 things I took apart of rebuilt).

stu

[powerlord]

nobody ? 😞 that's a pity. I'm gonna do it today then. I'll post here anything useful so others might have an easier time.

[tomato]

It’s interesting that the RA is especially poor, since I’m assuming this doesn’t suffer from backlash as it either gets speeded up or slowed down to maintain tracking? Are your corrections all on the same side? I would agree that if all the parts are in good order, then you should be able to fettle it to achieve a performance much closer to your other EQ6, though if the previous owner has destroyed the ALT/AZ adjustments, I wonder what other abuse has it received?
 

Good look with the second rebuild.

[powerlord]

RA wise - nope it was all over the place.

I've rebuilt it, but ran out of time setting up the worm screws tonight. Pity as looks likes nice seeing. But will just have to make do with one mount for tonight.

[1parsec]

Hi,   

I would record a number of guiding runs in PHD2 of say 10 minutes each but with the actual guiding corrections turned off.
The guide log will record the native tracking errors of the mount.
Then load the guide log in to PecPrep to analyse and display where the guide errors originate..
Pecprep takes out 99% of the guess work on where best to do your fettling.
 

[Starflyer]

Apologies for the slow response, I've rebuilt a few EQ6 / Pro / N / AZ mounts over the years, here are my suggestions.

Superlube is the grease to use, less is more, if you pack bearings with this stuff you'll end up with tight axis and stiction that causes guiding overshoot / ocsillation.

The teflon spacers are crucial in setting the correct worm to worm wheel alignment height, check this guide.

The worm bearings are the ones that make most difference, I've used ABEC 9 ceramic skate bearings very successfully in the past and they won't break the bank.

If the above fails then I'd try swapping the DEC and RA worms and worm wheels.