Olly and Tom's EQ8.

[jjongmans]

Hi Olly, too bad it's mechanical issue. An non-concentric wheel would explain why we didn't feel the backlash equally in every position... More EQ8 owners should have this. I'll ask my Australian friend that also has an EQ8.

Cheers,

Jeffrey

[ollypenrice]

Hi Olly, too bad it's mechanical issue. An non-concentric wheel would explain why we didn't feel the backlash equally in every position... More EQ8 owners should have this. I'll ask my Australian friend that also has an EQ8.

Cheers,

Jeffrey

Cheers, Jeffrey. You're right. Several other people with the same issue have appeared on the net, unfortunately.

Olly

[Zakalwe]

Well, I'm trying some planetary imaging on Jupiter. I don't hold much hope as its windy as heck here.

The tracking seems good though....I synched on Jupe and then had to slew away at speed to close the roof when the rain came. 5 mins later i told CdC to slew back to Jupe and it was bang on target. On a Chameleon chip (8mm) at 7 metres focal length (C11 with PowerMate 2.5) :smiley:

[libraryman]

Hi Olly, it was just an idea, i tried it and it seemed to change slightly, i just wanted someone else to prove or disprove my findings

I have to admit; i find it quite difficult to get a consistent assessment of the backlash. 

Thanks Ray

[ollypenrice]

It's getting worse. Peoples' Dec motors are now seizing up. http://stargazerslounge.com/topic/202845-eq8-dec-binding-or-total-failure/

As I said on the thread to which I'm linking here, I noticed a remarkable heat build up in my Dec motor after some slewing without any load or C/W bar in place.

For me that spells curtains.

Olly

[Astroscot2]

Having bought my mount 2 weeks ago and stil not had first light due to the weather this thread is making me very nervous indeed and I dont need that. How obvious is the backlash? Are we talking you can rock the mount and see the backlash clearly or is the issue during guiding?  Can anyone confirm the best way of testing ?   Wound not mind seeing some positive reviews  - think I will read Gina's thread agin ;-)

Mark

[ollypenrice]

Having bought my mount 2 weeks ago and stil not had first light due to the weather this thread is making me very nervous indeed and I dont need that. How obvious is the backlash? Are we talking you can rock the mount and see the backlash clearly or is the issue during guiding?  Can anyone confirm the best way of testing ?   Wound not mind seeing some positive reviews  - think I will read Gina's thread agin ;-)

Mark

Gina's seems fine and yours might also be fine, Mark.

The backlash is very obvious in my case. Just put a dovetail in the saddle plate. Let it overhang a bit on one side and feel that side. Simply wiggle the dovetail side to side in the direction of Dec rotation. On the slack side there is clear 'wiggle' in my case and when you think in terms of sub pixel guiding that means a lot. Then drive the Dec round a quarter rotation and try again. Better, worse, different? And another quarter, and so on. The Dec backlash should be at the limit of detection with your fingers. No more. I can make mine rattle. Note that you must drive the dec axis round on the motors, not move the puck on the clutches.

I'm guilty of recording two seized Dec drives when they turned out to be the same one on different forums. My apologies for that.

Olly

[Astroscot2]

Thanks Olly.  I did try the very same method you mention above last night, I would detect the slightest of movement in th dec, at first I thought the dovetail plate was not sitting in the saddle correctly,  The movement is ever so slight - I can just detect it by hand and sound I cant see it by eye? does this sound right ??

[ollypenrice]

Thanks Olly.  I did try the very same method you mention above last night, I would detect the slightest of movement in th dec, at first I thought the dovetail plate was not sitting in the saddle correctly,  The movement is ever so slight - I can just detect it by hand and sound I cant see it by eye? does this sound right ??

This sounds as if it might be OK to me. The thing is, is it consistent all the way round? If it is you can adjust the tension of the mesh should you find you need to. I'm guessing you have the version with the three blanked off holes on the Dec worm housing? These seem to have been introduced to facilitate this. Don't screw the blanking plugs all the way in, ever. They can drop right inside.

Olly

[Stephen]

This sounds as if it might be OK to me. The thing is, is it consistent all the way round? If it is you can adjust the tension of the mesh should you find you need to. I'm guessing you have the version with the three blanked off holes on the Dec worm housing? These seem to have been introduced to facilitate this. Don't screw the blanking plugs all the way in, ever. They can drop right inside.

Olly

Still not looked at mine yet (waiting for tripod to arrive) but would it be "safe" just to leave those blanking plugs out? Sounds like a disaster waiting to happen to me ...

[stephen_usher]

The level of Dec backlash on mine is small enough that on tracking rate 2 and pressing the button on the hand control it takes a couple of seconds to start moving the scope. So, in the scheme of things not huge. Actually no worse than my old CGEM mount.

Having said that, when I first set it up, before moving onto the correct pier adapter, I could see no decker able backlash.

[stephen_usher]

That should have said "decernable" and not "decker able". Autocorrupt strikes again!

[ollypenrice]

The level of Dec backlash on mine is small enough that on tracking rate 2 and pressing the button on the hand control it takes a couple of seconds to start moving the scope. So, in the scheme of things not huge. Actually no worse than my old CGEM mount.

Having said that, when I first set it up, before moving onto the correct pier adapter, I could see no decker able backlash.

I suspect this will just be a matter of where on the wheel you were.

I wouldn't leave the blanking plugs out. It is vital to keep a worm drive clean. (On the iEQ45 the drives are visible from the outside. That cannot be good.) I would just put a drop of Loctite on the plugs. They will come out OK but won't fall in.

Olly

Edited December 23, 2013 by ollypenrice

[ollypenrice]

Discernible. 

Olly

[Astroscot2]

I will try give it a try around the full rev of the dec worm tonight,   I dont recall seeig any blanked off holes in the dec housing, need to check this.

Mark

This sounds as if it might be OK to me. The thing is, is it consistent all the way round? If it is you can adjust the tension of the mesh should you find you need to. I'm guessing you have the version with the three blanked off holes on the Dec worm housing? These seem to have been introduced to facilitate this. Don't screw the blanking plugs all the way in, ever. They can drop right inside.

Olly

[Zakalwe]

I will try give it a try around the full rev of the dec worm tonight,   I dont recall seeig any blanked off holes in the dec housing, need to check this.

Mark

You need to check it at various points along the rotation.

one thing that I noticed with mine is that if you do a couple of full 360 slews in DEC the handset reports "Slew limits exceeded" and then rotates the DEC through another 360⁰. I have no idea what thats all about?

[Stephen]

I wouldn't leave the blanking plugs out. It is vital to keep a worm drive clean. (On the iEQ45 the drives are visible from the outside. That cannot be good.) I would just put a drop of Loctite on the plugs. They will come out OK but won't fall in.

Things like that tend to annoy me ... I think I'd probably put something better in or just electrical tape them over once removed ...

After my recent epic of a fan screw falling out INSIDE my 460ex, I'm not taking any chances

[ollypenrice]

You need to check it at various points along the rotation.

one thing that I noticed with mine is that if you do a couple of full 360 slews in DEC the handset reports "Slew limits exceeded" and then rotates the DEC through another 360⁰. I have no idea what thats all about?

There may be some internal cabling that mustn't get wound round too many times! Or maybe the encoders get confused of you exceed a full turn.

Olly

[Zakalwe]

There may be some internal cabling that mustn't get wound round too many times! Or maybe the encoders get confused of you exceed a full turn.

Olly

Hi Olly

I can't see any reference in the manual. If it was an anti-cable wrap thing then it wouldn't sent the axis off in the same direction surely?

[ollypenrice]

Hi Olly

I can't see any reference in the manual. If it was an anti-cable wrap thing then it wouldn't sent the axis off in the same direction surely?

Not a clue!

Olly

[Stephen]

Just to chuck my results in Olly ... mine is now finally set up and I can report there's no backlash in DEC and I've checked this every 15deg all the way round the axis, no feel of movement and hand controller does not report any movement either

[ollypenrice]

Just to chuck my results in Olly ... mine is now finally set up and I can report there's no backlash in DEC and I've checked this every 15deg all the way round the axis, no feel of movement and hand controller does not report any movement either

That's great. Just as it should be. 

Olly

[Astroscot2]

Well i do have some play in mine in dec and i suspect some movement in

RA! although that may just be my imagination . In dec its worse in one position

and the hand controller says its approx 2' s worth ..... what to do? Where's the booze

[ollypenrice]

At shorter FLs I can live with 2 seconds. My Tak mount defaults to 1.9 though I wish it were better. It certainly should be better. It is easy to find backlash in RA because the C/W shaft is so long that it will move a lot at the bottom for what is a small amount at the worm and wheel. If you feel only a tiny bit at the bottom of the shaft ne panic pas, Captain Mannering.

When setting up the guiding on the Mesu I set the Dec backlash to zero because that's what it is. Makes you think.

Olly

Edited December 23, 2013 by ollypenrice

[Sp@ce_d]

It's not good is it.. Yet another thread of disappointment with SW's lack of quality control! They are really shooting themselves in the foot over this. I've been holding back for ages on ordering one of these because of this very fear. Having recovered from my similar foul taste of QC failings with the Esprit, I had decided I was going to order one in the new year.  However, I think I'll wait until next season before making a decision now, by which time maybe I'll have a bigger budget for something else or go for the Mesu.

It's really annoying.. they can produce a good product but its so inconsistent. I won't buy another SW product again unless it's been thoroughly checked over by the dealer before shipping. If I were the dealer, I'd be demanding some compensation for having to do this to preserve the reputation of SkyWatcher!