EQ8 R P_ro RA & Dec. Adjustment

[AstroAndy]

Hello all

I was wondering if there was a guiding emulator, or a way to adjust an EQ8 R Pro in RA AND Dec. by reading the power output from a Pegasus power box.

This is to save me having to carry upwards of a 100 pounds of equipment over 4 flights of stairs (up and down), try to fix it, find out that I have to make another adjustment, and repeat the same operation multiple times. With real world conditions, ie. all my equipment on the mount when fixing it.

There is a whole sob story behind it, the short of it is: S/one "fixed" it (abt. 1000 pounds), it had terrible binding, he "fixed" it again, still binding, now I'm adjusting it myself, now it's too loose.

The repair in itself is theoretically straightforward, but practically, it's fast becoming a nightmare.

If I were to do it outside (after taking into consideration UK weather, cloudiness, rain, cold air humidity, etc.), I can't adequately handle millimeter Allen wrenches well. I have to go to a nearby schoolyard parking lot (my dark site is even further away), with all the problems that are associated with it.

If doing it inside the apartment, I won't know if it's adjusted right (hence the q. abt. the guiding emulator, or reading a power output.

Loosing a day (night) in the UK is like losing a week is loosing a month, nlol.

I'm on my last back, so any advice would be appreciated.

Andy

[Stuart1971]

Ok, so I have owned an EQ8 for a few years and have adjusted the worm mesh a few times, the issue with these mounts is that the large worm wheels are not made absolutely perfectly round, the tolerance is too big, and so you get binding in one area and it’s lose in another, so you can only adjust the worm at the tightest point, if you do it at the loosest point it will bind when it hits the tight spot.

what I did was to hook the mount up to a power supply that shows the amps reading, then slew the mount at a pretty quick speed and watch, as the mount hits the tight spot the amps it draws will go up quite a bit, mine would slew at around 1.5 amps then when it hits the tight spot it would climb to around 2.2 amps, so then you need to mark this point on the mount, and adjust the worm at this point, to adjust the worm just put a longish dovetail bar in the mount saddle and hold at the end and wiggle it, you will feel the backlash, then you adjust and repeat until you feel no lash at all, then test, but only very smalll adjustments are needed on the 3 adjuster screws for the worm block, also don’t forget to loosen the 4 bolts on the underside of the worm block beofre adjusting, and re tighten after each adjustment…

HTH

Stuart

[AstroAndy]

Hi Stuart

Thanks for the input..the sad part is, one of the 4 bolts on the block was already stripped when I got it (which I didn't find out until much later upon opening it (of course, the guy who "fixed it didn't re-thread it, ALTHOUGH I made him aware of it, and he said he'll include it in the price), and 2nd, the last of these 4 bo0lts I can't get to (I've read the instructions 😛 ) as it is behind the motor. So, how do I deal with the bolt I can't get to? How do you mark this spot on the mount? Just stop slewing and adjust?

I got about the same values from my power box, and all I need to do it is tighten it with the adjuster screws. My private suspicion is that the guy didn't even loosen the 4 block bolts, and in one instance, gave me bad advice by saying all I need to do was worry about the center adjustment screw which holds things in place. So, after waiting 4 months (instead of the 2 weeks he said), I got my mount back too tight (stiction all over the place), and, although the guy came by once and "fixed" it again, still stiction. What's on me is that I loosened them too much now , so I'll have to redo things. I've been monkeying around with this thing since a year already (between UK weather, shlepping equipment, job, etc.) I don't get to go out too often.

[Stuart1971]

6 hours ago, AstroAndy said:

Hi Stuart

Thanks for the input..the sad part is, one of the 4 bolts on the block was already stripped when I got it (which I didn't find out until much later upon opening it (of course, the guy who "fixed it didn't re-thread it, ALTHOUGH I made him aware of it, and he said he'll include it in the price), and 2nd, the last of these 4 bo0lts I can't get to (I've read the instructions 😛 ) as it is behind the motor. So, how do I deal with the bolt I can't get to? How do you mark this spot on the mount? Just stop slewing and adjust?

I got about the same values from my power box, and all I need to do it is tighten it with the adjuster screws. My private suspicion is that the guy didn't even loosen the 4 block bolts, and in one instance, gave me bad advice by saying all I need to do was worry about the center adjustment screw which holds things in place. So, after waiting 4 months (instead of the 2 weeks he said), I got my mount back too tight (stiction all over the place), and, although the guy came by once and "fixed" it again, still stiction. What's on me is that I loosened them too much now , so I'll have to redo things. I've been monkeying around with this thing since a year already (between UK weather, shlepping equipment, job, etc.) I don't get to go out too often.

I am guessing you sent it to Dark Frame Optics for the overhaul, if so that was your first big big mistake….

The three screws that adjust the worm are a push pull operation, so you have to alter all 3 each iteration of adjustment, the middle one pushes again a block the outer 2 are in threaded blocks, so you loosen the middle one a tad, and then tighten the outer 2 a tad, then retighten the middle one, that is to close the gap, to make the gap bigger, you loosen the outer 2 then tighten the middle one…small amounts about 1/16th of a turn will be enough teach time…

‘As for the screw you can’t get at, that was not an issue on mine as I had the older EQ8, not the newer EQ8-R model, as they are a bit different….but you only need to crack these bolts, not take them out or loosen them right off…

Edited December 12, 2023 by Stuart1971

[AstroAndy]

You guessed right, lol.

Yup, that's what I did, but due to the binding, I probably went to the other extreme and made the gap too big, so I'll have to carefully approach the correct position again, with an eye to where it starts binding on the gear. Shame, though, at calibration, it cleared the backlash in 3 steps, probably because it was too loose. On the other hand, after the repair, I could hardly move the belt by hand, so it was too tight. Thanks for the advice.

[Stuart1971]

47 minutes ago, AstroAndy said:

You guessed right, lol.

Yup, that's what I did, but due to the binding, I probably went to the other extreme and made the gap too big, so I'll have to carefully approach the correct position again, with an eye to where it starts binding on the gear. Shame, though, at calibration, it cleared the backlash in 3 steps, probably because it was too loose. On the other hand, after the repair, I could hardly move the belt by hand, so it was too tight. Thanks for the advice.

Well if it helps, as you will never be able to remove all the lash, what I did was had my PA about 2 mins out, and then just guided in DEC in one direction only with PHD, this means that the DEC will always drift in one direction due to the PA not being optimal, and then the guide commands just come from one direction, and the lash then becomes moot, as the axis never changes direction…

As for the RA, backlash does not matter on that axis as it never changes direction anyway, so no need to touch that….👍🏻

[martin_h]

16 hours ago, Stuart1971 said:

Well if it helps, as you will never be able to remove all the lash, what I did was had my PA about 2 mins out, and then just guided in DEC in one direction only with PHD, this means that the DEC will always drift in one direction due to the PA not being optimal, and then the guide commands just come from one direction, and the lash then becomes moot, as the axis never changes direction…

As for the RA, backlash does not matter on that axis as it never changes direction anyway, so no need to touch that….👍🏻

Exactly what I do with mine