AVX alternative

[Shelster1973]

That may have had a few knocks along the way, both in  my general use when on a tripod and fell over a few times and also when releasing it with the 'gentle persuasion.  Have decided that will not be fitting the clutch lever when I do the rebuild as it was fouling on the casing, despite several adjustments and moves, so will just leave it with the bare brass you can see there and adjust it with a universal nut rounding tool (aka adjustable spanner)

Will get plenty of pictures from different angles and post them so others can learn from my experiences so far

[iapa]

I did find that I needed to reposition the clutch lever several times before it stopped fouling on either the mount plat of motor housing.

Did a Robert the Bruce on it.

[Shelster1973]

He's Alive.......

New bearing arrived, fitted, mount rebuilt and tested fine.

Checked the RA limits and they are both set for -20 at present.  When I get my imaging kit mounted will find out what my limits actually are and change these so that I do not get a repeat of the OTA fouling again and have to go through all this.

Will be putting up a shed load of pictures later on to show the steps I took to get it back together, along with comments and thoughts.  May be best if a mod moves this thread now to the DIY section as it has kind of morphed into something that it did not start off as (may need a re-name too)

Am a very happy bunny now.  £12 for a new bearing and a few hours of blood, seat, swearing and tears has saved me a fortune.  

Now just need some clear weather to redo my PA and get to imaging.

[iapa]

Excellent news

Glad it's all working again

[Shelster1973]

Right...images time

1st up is the replacement thrust bearing (right hand side of image) against the old one

as you can see, a much more substantial bearing that also moves more freely.  Hopefully will have some added benefit in use.

Now to rebuild the bad boy

1st in is a small PTFE washer that sits at the very top inside of the axis housing

This helps the large geared rotator move and also stops any fouling with the saddle bolts too.

2nd in is the geared rotator

This has a large PTFE washer that sits on it finally

tbc........

[Shelster1973]

Next up is putting the fixed rotating bearing back into the axis casting

I did think about replacing this one too, but checking on RS Supplies, the bearing fitted is a decent bearing and sufficient for the job ion hand.

Next up was putting the 1st part rebuild back into the housing.  This is fairly straight forward and it just slots straight in.

Now comes the time to use the new bearing.

You will have noticed in the post previous to this that the new bearing was significantly taller than the old one.  This worked in my favour as in my early efforts to remove the retaining ring and missing the last grub screw...there may have been some slight damage to the thread that made it rather difficult to screw the ring fully back down.  The only down side of this is that the hole that is in the casing to access the grub screw holes in the retaining ring does not now line up the grub holes.  This will be remedied with a new hole being drilled into the casing and the grub screws fitted.

Speaking of which........

At present it is retained with some UV cure adhesive.  Is worth noting that this retaining ring should not be overtightened as it will then cause the axis not to rotate as freely as desired.

Next post......worm gear, motor and drive cogs

[Shelster1973]

So...onto the worm gear

The tiny grub screw is used to get the mesh between the worm and the cog just so.  Can take a bit of fiddling to get it just right, but is well worth the time spent on it.  The tow bolts that hold it down only need to very lightly 'snucked' tight.  Over doing these will casue binding and make it difficult for the motors to rotate the axis (have T-shirt on that one).  I fitted the cog so that I could gauge by hand the correct level of tightening, as once the motor is fitted, you are not able to get access to those bolts.  When correct, you should be able to rotate the assembly by hand turning the cog (this does cause a wee bit of finger pain...but hey ho).

Next fit is the control board housing and motor itself

The housing is a straight forward fit.  A few screws and all is done.  As for the motor, I left the cog fitted when replacing the worm housing in place as this is used to get the correct positioning for the motor.  Fit it using the 3 screws, but leave them loose enough so that you can still move the motor up and down the mounting.  Re fit the final drive cog and move the motor so that you have minimal backlash.  Be careful here as you can have the cogs too close together and end up with them binding, which will make is difficult to rotate (plus lots of other nasty things....). When in position, tighten the top visibly screw, remove the cog, tighten other two then refit cog and tighten to the shaft.

The final part is to fit the opto sensor disc (or spinny light counter as I call it)

I mounted this so that is was more or less central to the sensor.  This best distance so that it should not foul on the sensor before you reach the RA limits.

 

I then fitted the motor cover.  This was a bit of a pig to do and needed a wee bit of brute force and ignorance to get into place.

Now it is just a case of putting this back onto the rest of the mount and you are back in business.

Hope that helps a few others who are looking at doing this....or are mental enough to want to tune their mount

 

[Droogie 2001]

Thanks for the detailed repair steps, its interesting to see what's inside my mount.

Glad to hear you have resolved the issue and look forward to a report on the PA. Hopefully it will be better than when it came out of the factory.

 

[Shelster1973]

My PA was fairly nailed down prior to the upset, thanks to the micro adjusters I fitted on my last mod of the mount (you can see one in the pic of the mount houseing prior to the insertion of the ratation bearing)

Will be good to see whjat my periodic error is like now too.  Did not have it traced prior to the rebuild, so nothing to comapare to, but can use my guiding graphs as a good indication.  Are there any free ways of recording PE?

[iapa]

3 hours ago, Shelster1973 said:

Will be good to see whjat my periodic error is like now too.  Did not have it traced prior to the rebuild, so nothing to comapare to, but can use my guiding graphs as a good indication.  Are there any free ways of recording PE?

Will the logs from PHD2 not show PE when viewed with PHDLogViewer (http://openphdguiding.org/phd2-log-viewer/)

[Shelster1973]

5 minutes ago, iapa said:

Will the logs from PHD2 not show PE when viewed with PHDLogViewer (http://openphdguiding.org/phd2-log-viewer/)

They very well may.....have never really delved into any of this before, so each day is a school day here.

Will drag some old log files from my old laptop this weekend and see if they revela anything there.  Also have to drag a few config files over from that to my new laptop too...two birds one stone

[Shelster1973]

Finally managed to test out last night...and all is great in teh world of mounts.

Now just need to work out where the nast mains interference that is appearing in my CCD captures is coming from.  May be a loose earth somewhere or a mains cable crossing a signal cable.

Will do some looking and resolve that, but am glas the mount works.

[iapa]

7 hours ago, Shelster1973 said:

Finally managed to test out last night...and all is great in teh world of mounts.

Now just need to work out where the nast mains interference that is appearing in my CCD captures is coming from.  May be a loose earth somewhere or a mains cable crossing a signal cable.

Will do some looking and resolve that, but am glas the mount works.

congrats of a successful repair....