SW EQ8 R PRO Declination Backlash Problems

[AstroAndy]

Hi Folks

I have had my EQ8 R Pro since about 2 years. Ever since that time, I've had a large declination problem (3000ms) which I finally decided to fix.

FLO sent me the instructions on how to do this.

Here are my findings.

The left adjustment and right screws were misaligned before I made any adjustment (refer to attached pics).

That is to say, the markings that I made showed different positions, whereby the screw on the left had play, and the right one was tight (after loosening the middle screw). I don't know whether it's supposed to be that way, for now, I have just tightened the left one slightly, to bring it into the same position as the right one.

The one bottom screw holding the block in place is loose, and I can't tighten it (it is like a car in neutral, keeps turning in the thread, but doesn't tighten (also refer to pic.) That can't be good.

I have done a test run after the adjustment, and it sounds normal, so that part is good.

What worries me is that the misalignment was only on the left side (loose adjustment screw and loose fitting attachment screw).

I've used this mount for 2 years (infrequently), and, except for the dec. backlash, never had a problem, loose screw nonwithstanding..

Now my stupid question, how important is that third screw holding the block to the plate (Saturn is fast going away, and now I'm paranoid about imaging with heavy equipment on the mount).

I assume it has some purpose, otherwise it wouldn't be there.

Is there a service in the UK that could remachine this thread, or otherwise permanently and reliably fix this problem?

Regards

Andy

 

 

 

Edited November 13, 2022 by AstroAndy

[jacko61]

Can you post the instructions FLO sent you Andy?  I have a dec backlash issue with my EQ8R pro (although nowhere near as severe as yours) so it would be good to know how to adjust it.

Graeme

 

[AstroAndy]

Hi Graeme

Here they are, I found them pretty straightworward.

Step 1 – Remove the Cover
The cover is in two sections and is secured by numerous bolts, some deeply recessed, requiring quite a mixture of Allen keys.

Here is the cover in question:

Photo 1

As indicated on the picture above, first remove the three small screws at the front.  They are accessible and this step is simple.  Put them somewhere safe!

Then the four bolts on the top, as indicated.  These are again not difficult but you will have to rotate the dove plate to allow access to the rear two bolts.  Put them somewhere safe!
You will then find that the top section of the cover lifts off, exposing the worm gear assembly.

Finally, there are two deeply recessed bolts up inside the holes in the bottom of the cover.  You might find it tough to locate the bolt heads with your Allen key but persevere.  They shouldn’t be too tight.  Carefully remove them and the bottom of the cover, exposing the drive motor, belt and adjusting screws.

Now see the next photo.  First, slightly loosen the three bolts holding the worm gear to the block, as indicated in the photo.  You might find that these bolts are very tight but they should move with a firm pull.  Do make sure your Allen key is properly located in the bolt head before heaving on it though or you could damage the bolt.  It is important that these bolts are only slightly loosened to allow the block to move when you make the adjustment.  The bolt to the right is slightly blocked by the motor so you might need a stubby Allen key to get at it.

Photo 2

Now you need to move to the upper block as shown in the next photo.  The centre screw locks the position and the outer two adjust it.  Firstly, mark the position of the two outer bolts with a marker.  This is so you can always go back to where you were in the event of problems.  Now turn both outer bolts half a turn anticlockwise.  Then use a 2.5mm key to unlock the central screw.  I found this to be very tricky, because the lock bolt is deeply recessed and you will have to use the long shaft of your Allen key, which makes it tough to apply enough turning force to unlock the bolt.  When it is loose, turn it half a turn counterclockwise.

The next step is critical.    You need to turn both outside bolts by the same amount.  The manufacturer’s instructions suggest a half a turn in from their original position but if your mount, like mine, only has a small amount of backlash, but enough to stop PHD2 from calibrating, I have found this is way too much and you could lock up the gear, possibly causing damage.  I found you only need to turn the two bolts by the smallest amount.  

So the best procedure is to screw both outside bolts in to their original, marked positions and then go a small amount past that position – no more than about 5 degrees.  Then go back to the centre hole and screw it in until it locks.

All of this is detailed in the next photo.

Photo 3

Once the centre bolt is locked, go back to the gear plate bolts which you slightly loosened in the very first step and re-tighten them securely.

Power up the mount and use the hand controller to slew the mount in declination.  DO NOT use automatic slewing or homing because you want control of this step.  Make sure you slew all the way round in both directions to be sure you have covered all possible positions of the mount.

If the mount sounds OK during this operation (listen for any signs of binding) then leave the covers off and attempt to calibrate your guider once it’s dark.  If it is still showing backlash then re-do the above procedure to screw in the outer adjustment bolts a little more.  Repeat until you are happy.

NOTE:
If, when you slew the mount using the hand controller there is any noise or signs of binding, stop the slew immediately and back off some of the adjustment you made until the noises go away.

 

Edited November 13, 2022 by AstroAndy

[AstroAndy]

Update, I've been informed there is a 4th bolt (which you can't get to w/ the block attached, just posting for completion.

[jacko61]

Thanks Andy. That's perfect.

 

Graeme

[alacant]

Hi everyone

I wonder if this example (from the latest batch of eq8-r version 3) holds the record for out-of-the-box backlash?
One is out of the box, the other after adjustment.

I'll let the graphics speak for themselves!

 

[ShinyTwelve]

Why on earth is a £3.5K mount so poorly setup before delivery?

[AstroAndy]

I don't get it...should be better for what they call an observatory grade mount. I'm not a mechanical wizard, but in mine, I've seen backlash as little as like 120ms..When I opened to fix it myself, one of the holding bolts was stripped out. I finally sent it in to Dave at Darkframe optics to get everything sorted, where it has been sitting for the last 4 months, lol.

 

[alacant]

On 13/11/2022 at 11:17, AstroAndy said:

there is a 4th bolt (which you can't get to w/ the block attached

Hi

Just in case anyone else is adjusting,  I wonder if that should perhaps read, '... which you can't get to w/ the motor attached'?

4 hours ago, AstroAndy said:

it has been sitting for the last 4 months

Oh dear. really? You mentioned a broken bolt (?). Maybe some parts are on order? Dunno. The backlash adjustment only takes around 20 minutes or so.
If you don't want/have the time/etc to adjust/fix yourself, this guy es perfectionista.

Cheers

[AstroAndy]

Gracias, desafortunadamente, no vivo en España (todavia), pero en esa zona poco favorecida cuando se trata del tiempo  conocido como Reino Unido, jeje.

I know about the fourth bolt..I´m also ok w/ backlash adjustment, I just didn't want the hassle, and may as well get that stripped bolt retapped.

[alacant]

12 minutes ago, AstroAndy said:

no vivo en España

¡Que lástima! Es que en móviles en este foro, no se ve dónde se vive la gente.
On this forum on 'phones, you can't see where folk live.

[Stuart1971]

5 hours ago, AstroAndy said:

I don't get it...should be better for what they call an observatory grade mount. I'm not a mechanical wizard, but in mine, I've seen backlash as little as like 120ms..When I opened to fix it myself, one of the holding bolts was stripped out. I finally sent it in to Dave at Darkframe optics to get everything sorted, where it has been sitting for the last 4 months, lol.

 

Lol, good luck in getting that mount back anytime soon…..best to drive to him and collect it….not a service I would ever use….good luck…👍🏻