Hi Michael, appreciate the phone chat today. I changed the steel worm with another older one I had and the 5 second backlash is gone. No idea why but I'm not complaining.

Tom

Hello Fellow Losmandy Users

I've just started to strip down and service my 17 yr old G11 mount. Tanya, at HGM, kindly confirmed it's age from the Serial Number found on the underside of the Mount base.
I am the sole owner of this mount and slightly ashamed to admit that I have never carried out any maintenance or tuning adjustments ever, until now.
The mount has been sitting on my concrete pier for this entire time covered in the most part with just a tarp but laterly, since July 2020, with a more
upmarket Telegizmo 325I cover. In these 17 years there was an extended period of non-use which I estimate to be around 8-9 yrs. I restarted using the mount in July 2020 and got
some great help from people here at that time, mostly on what to watch for when re-commissioning the Gemini - 1.

I was some what apprehensive about starting this project but to my great surprise am finding the actual 'breaking down' of the mount into its individual components
to be really pleasantly straight forward and rewarding, mostly due probably to the mount's modularity. The only tools needed so far have been Hex/Allen keys.
So far I've degreased the two roller bearings found in each axis and got these spinning nicely ready for some SuperLube, I am using a citrus based degreaser from 'Muc-Off'. I believe the upper bearings were ceased but now spin freely.
I've removed the old grease from both worms and worm-wheels, without affecting the worm adjustment, in preparation for regreasing both worm and worm-wheel with a small amount of SuperLube.
Have also checked the small screws on the Oldham couplers for tightness - all ok and no loose screws.
Clutch disks and many other parts have been degreased and cleaned. Progress is good and I am enjoying the experience and it's given me the confidence to carry out this work at much
smaller interval than 17yrs in the future. I might post a photo of the mount parts before re-assembly, hopefully tomorrow [Friday].

But to my questions that I am hoping someone will be able to help me with.
Q1: I have attached an image of the mount base [Polar Block' section [?]. I've marked [with Red/Blue Arrows] the two screws located on each side of the mount and am thinking that when polar aligning
the mount that the Red highlighted central screw is the point around which the Alitude adjustment pivots and should not be loosened when PA. The Blue arrow indicates the Altitude locking screws, one each side, which do
need slackening off during PA adjustment and then retightened. Have I interpretted their purpose correctly?

Q2: I am planning on dissassembling the 'Polar Block' on the mount base for access to, cleaning and relube of the long threaded Altitude and Azimuth rods etc and was wondering if it is 'safe' to remove all four of these screws.
I have some mount dissassembly instructions for a G11 but it is based on an earlier mount [badged as Celestron] but this only has the single Red pivot /locking screws.

Thanks in advance for any help with these queries.

Terry [uk]

Hi Robert,

My GM8 had a loose DEC saddle dovetail.? I discovered the 2 top mounting bolts were slightly too long...the dovetail was slightly loose.??

My solution was to file off the 1/4-20 bolt ends so the plate was finally snug.??

Please check your dovetail plate for any wiggle.

After that, mount your scope.? Grab the front and back of the scope and try to wiggle it in DEC.? It should ideally not wiggle at all. If it dies wiggle, figure out where:. Is the worm shifting left to right?? Is the worm lightly snug into the ring gear?

All the best,

Michael

On Thu, Mar 4, 2021, 2:55 AM McFarlane, Gilbert via <gilboastro=[email protected]> wrote:

Stuck at home, I decided to learn more about phd2, and try to tweak my mount.? ?All my efforts did not seem to have much of an effect.? ?I generally achieve RMS of about? .25px ,? and about 1.0" to 1.6 ".? ?This doesn't sound great to me, I was hoping for about half of that - but my images seem to be ok.? ?(Guide camera is QHY 5L-II with 3.75 um, with 130mm QHY mini guide scope.? ?Camera for imaging is a K5 Pentax dslr.? Imaging scope is an 80mm f6 APO with a Televue 0.8x flattener.)? ?

The most irritating part has been trying to reduce the Dec backlash measured by PHd2 - which has stayed at 6 - 9 seconds despite numerous lubes, adjustments, and even Belleview washers.? ? Motor is attached very tight.? I have tried changing the balance, tight axis, loose axis.? Everything I know to try other than replacing the motors or the little plastic motor connectors - but they seem tight.? ?I tried switching the motors, but no change in Dec backlash.? ?Any thoughts?

The mount has the separate worm blocks and brass worms.? ?Using the 492 controller and the ST4 camera controlled interface and USB 3.0.

Thanks, Gil
Ventura, CA

Stuck at home, I decided to learn more about phd2, and try to tweak my mount.? ?All my efforts did not seem to have much of an effect.? ?I generally achieve RMS of about? .25px ,? and about 1.0" to 1.6 ".? ?This doesn't sound great to me, I was hoping for about half of that - but my images seem to be ok.? ?(Guide camera is QHY 5L-II with 3.75 um, with 130mm QHY mini guide scope.? ?Camera for imaging is a K5 Pentax dslr.? Imaging scope is an 80mm f6 APO with a Televue 0.8x flattener.)? ?

The most irritating part has been trying to reduce the Dec backlash measured by PHd2 - which has stayed at 6 - 9 seconds despite numerous lubes, adjustments, and even Belleview washers.? ? Motor is attached very tight.? I have tried changing the balance, tight axis, loose axis.? Everything I know to try other than replacing the motors or the little plastic motor connectors - but they seem tight.? ?I tried switching the motors, but no change in Dec backlash.? ?Any thoughts?

The mount has the separate worm blocks and brass worms.? ?Using the 492 controller and the ST4 camera controlled interface and USB 3.0.

Thanks, Gil
Ventura, CA