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Niel,

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Failure to flip usually results from your mount limits not being set right:

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please see the following Losmandy video:

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John

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Losmandy G11G2 on pier; refurbed Losmandy G11 with OnStep controller; SkyShed design roll-off observatory; ZWO ASI2600MM-P; ZWO ASI071MC; Sky-Watcher Esprit 100 ED with field flattener; Celestron C925 Edge HD with 0.7XFR, William Optics Zenithstar 61 APO; PHD2, NINA, Sequence Generator Pro and PixInsight user

Pier side refers to where the telescope is located referenced to the mount itself, regardless of where it’s pointing. For instance, you can have the scope on the west side of the mount pointing east and, later in the session, if your limits allow it, it will go past the meridian and be looking west. All throughout this example, the scope is pier side west.

at least I think this is the right way but, I’ve been proven wrong before so who knows? :)

Thanks for the reply, Ed

I think of it as where the telescope is pointing. So in the northern hemisphere, standing behind the mount, west is pointing left and east is pointing right.

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No expert here, but I believe that is the gist of it.

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So far as getting meridian flips working, for me it was all about the settings here:

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I would tell you the settings on mine, but it isn't set up right now. If I do soon, I will post again.

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Well, I've had it.? I'm just going to send the whole thing to Losmandy and see if they can figure it out.? My eq6-r is currently guiding at 0.19" and the g11 is doing this.??

On Wed, Feb 26, 2025 at 04:12 PM, Thomas Kallenbach wrote:

I can remove the new RA extension

The 12" extension is much more responsible if the issue comes for these add-ons.? Because the 12 inches of extension increases the inertia the pier must dampen much more that the slight increase from the RA extension.

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Doug

Hey Thomas,

I've just been following the thread silently as I'm at just as much of a loss as anyone else regarding a definitive source, but I did have a thought:

Your very tight clutch technique may have worked under the pre-RA-extension configuration, but then the RA extension would have extended the moment arm on your RA axis by a few inches. This small difference in moment arm could be just enough to induce a very slight deformation in the RA axis when the clutches are loaded so heavily. I hypothesize that a reduction in that stress will smooth out your guiding, and that stress reduction could come from lowering your clutch pressure or removing your RA-extension, which it sounds like you already have.

I have had my mount for a couple of years now. I also have the RA extension and I was also noticing that my guiding was getting worse. I tried to tighten down my clutches but just couldn't improve it. I had it down to .25-.45 arcsec about a year ago and it just started creeping up to over 1 arcsec even when the seeing wasn't that bad. I tried worm adjustments, clean and relube, clutch pad replacement with Michael Herman's pads; just about everything.

Ultimately, on this forum I came across the advice to have the clutches barely tightened so the mount could easily be pushed if needed. I carefully rebalanced (rolling DEC to 0 degrees) and marked my mounting plate with my saddle so I could easily repeat the position. I tried barely tightening to contact, polar aligned and, hit "Play" in the NINA Advanced Sequencer.

Currently watching the mount settle at .3-.7 arcsec again with none of those severe sawtooth RA excursions like I saw before.

I'm sold on Chip's "barely make contact" with clutch technique.

Also, when I took my axes apart to clean and relube I noticed some wear on the shaft where it touches the needle bearings. I am pretty sure I induced this by over tightening my clutch over time.

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I can imagine your frustration right now; I bet we have all been there at some time in this hobby, and I hope the RA extension removal gives you some instant satisfaction so you can get some imaging in. But I would encourage you to not give up on the RA extension and give it another shot once you feel like you aren't chasing ghosts in the mount.

Wishing you clear skies and a rewarding imaging session,

Ryan

Thanks Paul.

I decided to remove the RA extension.?

We'll see what happens.

Tom

On Wed, Feb 26, 2025 at 04:12 PM, Thomas Kallenbach wrote:

Hello Everyone,

Tonight might be a clear night so I thought I would set up the scope.? I read in another thread that tightening the clutches excessively could cause jerky movements.? I may have tightened the clutches beyond what was necessary to hold the scope.? I can try it tonight with the clutches only as tight as necessary or, I can remove the new RA extension and see if that makes a difference.? Remember, this problem showed up right after the RA extension and 12" pier extension addition.??

I sure appreciate any advice.? But if I am going to take the RA extension off, I need to get started.

Thank you all,

Tom

Hello Everyone,

Tonight might be a clear night so I thought I would set up the scope.? I read in another thread that tightening the clutches excessively could cause jerky movements.? I may have tightened the clutches beyond what was necessary to hold the scope.? I can try it tonight with the clutches only as tight as necessary or, I can remove the new RA extension and see if that makes a difference.? Remember, this problem showed up right after the RA extension and 12" pier extension addition.??

I sure appreciate any advice.? But if I am going to take the RA extension off, I need to get started.

Thank you all,

Tom

Tim,

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If you are tightening down the clutches because you have slippage, it sounds like you have oily discs as was mentioned. But instead of a wrench you may wish to invest in the Losmandy clutch knobs which have the three handles, and which are more easily turned than the original smooth ones. Rubber gloves work better than bare hands also. One final snug should do it. If you watch the Losmandy videos on YouTube, that should give you an idea of how to adjust the worm tension with either the spring-loaded or earlier types.

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Good luck,

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John

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_____________________________________________________________________________________________________________________________________________________________________________

Losmandy G11G2 on pier; refurbed Losmandy G11 with OnStep controller; SkyShed design roll-off observatory; ZWO ASI2600MM-P; ZWO ASI071MC; Sky-Watcher Esprit 100 ED with field flattener; Celestron C925 Edge HD with 0.7XFR, William Optics Zenithstar 61 APO; PHD2, NINA, Sequence Generator Pro and PixInsight user

On Tue, Feb 25, 2025 at 03:41 PM, <tshelley@...> wrote:

Paul: The drive noise is what you'd hear if you touched the pointed end of a phillips screwdriver to a portion of the worm gear housing and the other end to your ear. I use the mounting bolts to avoid any moving parts. Otherwise the guiding is totally silent.

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Michael: This is some good advice. I'm afraid that it will be some time before I can get back to the hobby, darn that life thing.

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"Do you have a wavy washer in your clutch assembly? That, along with too much pressure could explain why the wear is both wavy and uneven." Yes I have the wavy washer, in the correct order. Now as to too much pressure, that's a possibility. My hand strength is very low and I've had to use a wrench to tighten the main axis clutches. So I could be putting too much pressure on the bearings. I tighten until I cannot move the scope manually.

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"I'd be most suspicious of binding in worm/ring gear interface."

I've spent a lot of time tuning this particular parameter, but I can certainly back off a little and see what happens.

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Thanks again for the great advice. I'll post again when I can do some controlled work with the new rig.

Tim

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Hi Tim,

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A lot of MBY's advice is excellent but you should NEVER use a tool or wrench to tighten the clutches.? Overtightening the clutches using a tool or strap wrench is one of the best ways to warp the thin aluminum clutch plates that are attached to the large axles.? You should never be able to fully lock up the Losmandy mount clutches, they are designed to slip on purpose.? If you do use a strap wrench you'll can distort the clutch discs permanently.? This will require having the clutch face reground or maybe flycut to correct so the clutches have the full friction surface area available.??

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Excessive clutch pressure also increases the load on the upper thrust bearings and can damage the thrust bearing races / washers. The standard part number for these thrust bearings are rated to approx. 6,600 pounds which sounds like a lot but the amount of pressure put on these bearings is very high when you crank down on the clutch knobs.? Think about it, how much load is being placed on these bearings once you take up all the slack in the RA axle then turn the RA clutch knob 1/4 of a turn against basically a solid block of aluminum and stainless steel?? Screws are very simple but also very powerful machines.? I don't know the thread pitch of the clutch knobs but that will be a lot of force with the only really compressible part being the plastic clutch disc.? Now I feel the need to go put a pitch gauge on the threads and calculate the load on those bearings.? But trust me it is quite high.?

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As far as spring loaded worm block adjustments go you want to use the lowest spring pressure that keeps the worm teeth fully engaged in the worm gear mating surface, no more.? This is a sort of dynamic load but you can get it to work for a variety of payloads and polar moments.? When adjusted just right the worm will be engaged but you will see the worm block moving slightly as the mount tracks.? You will also want to adjust the worm block lifting bolt to minimize the current used to get past the tight spot in the worm / worm gear.? I use an ammeter on my bench power supply to adjust my G11G and GM8G mounts and it works very well.?

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I recommend using the Losmandy grease kit but an easy to find, probably better grease is Superlube with Teflon spiked with 15% by weight molybdenum.? I have been using this blend for over a year and cannot say I see any improvement in wear on the thrust bearings or worms vs the standard Superlube with Teflon.? I have used Superlube with Teflon for decades and it has been the best mount drivetrain lube for several reasons.? Wear is very minimal, the pure synthetic base oil has minimal to no separation in extreme desert heat.? This means that when applied correctly Superlube won't melt, run off and migrate to contaminate your clutches.? Superlube also doesn't get stiff when cold and retains its very low start up torque which BTW is much lower than MP50's starting torque. These traits matter for consistent PE in hot or cold while guiding.? The easy to see translucent white grease shows contamination easily helping you to know when maintenance is needed.? Food grade grease is reasonably safe to handle.? ? ? ??

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Paul: The drive noise is what you'd hear if you touched the pointed end of a phillips screwdriver to a portion of the worm gear housing and the other end to your ear. I use the mounting bolts to avoid any moving parts. Otherwise the guiding is totally silent.

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Michael: This is some good advice. I'm afraid that it will be some time before I can get back to the hobby, darn that life thing.

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"Do you have a wavy washer in your clutch assembly? That, along with too much pressure could explain why the wear is both wavy and uneven." Yes I have the wavy washer, in the correct order. Now as to too much pressure, that's a possibility. My hand strength is very low and I've had to use a wrench to tighten the main axis clutches. So I could be putting too much pressure on the bearings. I tighten until I cannot move the scope manually.

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"I'd be most suspicious of binding in worm/ring gear interface."

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Thanks again for the great advice. I'll post again when I can do some controlled work with the new rig.

Tim

Hi Tim,

A couple of link corrections

For whatever reason John,? the part number got clipped off the links for these two.

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There are long discussions about reduction of PE and improvements in tracking in the archives.

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From what you describe is happening regarding guiding, I doubt that the bearings you're asking about are at the root of it.

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I'd be most suspicious of binding in worm/ring gear interface. If could be just a needed slight adjustment of worm pressure to account for a high spot that's still within ring gear tolerances, a contaminant on the ring gear or similar lubrication issue.? Guide pulses are a much smaller force than average RA tracking forces, so RA tracking could still push through an area that's binding but the guide pulses become ineffective.

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There are a few ways to test this out, but I'd suggest to back off the worm slightly and see if the problem goes away. A lot of guiding issues are caused by too much worm pressure.

Be mindful too that the relationship beteen RA position and ring gear position shifts if the clutch is released or slips. This is why a ring/worm binding issue may not be consistent with RA angle.

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Seeing uneven and wavy wear on the large thrust washers is not what I'd expect.

I agree with John, with that much wear they should be replaced.? The important question though is WHY you're getting this much wear and why it's uneven. An Unbalanced load would tend to pinch the outer edge of the bearing. Heavy over tightening of the clutch would pinch the inner edge. Contamination, incorrect lubrication, or uneven pressure causing a pinched bearing can cause premature wear. If the bearing is pinched it will push lubrication out of the bearing and it can end up contaminating the clutch, causing futher tendency to over tighten in a viscous cycle.

Do you have a wavy washer in your clutch assembly? That, along with too much pressure could explain why the wear is both wavy and uneven.?

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The clutch on the G11 is designed to slip under pressure, not lock up tight.? If you are applying a lot of pressure because the clutch is slipping the most likely reason is load balance or clutch plate contamination. Worn plastic clutch plates can be roughend with sandpaper, but be sure to clean them to remove any trace of abrasive or plastic dust. IME though it's probably lubricant that's migrated into the clutch.?

With excessive pressure, I think Chip has mentioned in past threads there is risk of warping as well, so at this point surface flatness is something to check while you've got things apart. If?

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If you prefer a higher slip resistance clutch, I suggest Michael Herman's high friction replacement clutch disks.

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Since you are cleaning and relubricating,? be aware it is very easy it over lubricate the mount.?

Being fully machined, tolerances are very tight. It's only necessary to just coat the bearings. Just enough is all you want.? Clean away all traces of old lubricants, make sure all solvents dry and there is no residue. Check the bearings dry to be sure they're turning freely and there is no damage before lubrication and assembly. It isn't difficult, but I found it is very easy to get lubricant where it doesn't belong unless you're very very careful what you touch once lubricant gets involved.

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The Jet-lube Artic and Jet-lube MP-50 are aircraft spec lubricants. The big advantage in the Jet-lube Artic is the extended temperature range. If you are in an area where you have very cold temperatures or wide extremes,? stick with it. I've had good success with Superlube as have others,? but I'm in a temperate area. YMMV

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The exception is lubrication for the worm/ring gear interface. This spot is sensitive to lubrication for tracking/guiding performance. I'd take John up on his offer for MP-50. There are a couple of alternatives that you'll find in the discussion threads, such as a brake caliper high temp grease that Michael Herman suggests, but none are? inexpensive, and you'll pay for more than you'll ever use.??

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For full disassembly of the motor drive train you'll want an Allen hex long driver set in SAE English 64ths. I'm not sure about the tucked motors,? but with the untucked ones there is one tight access spot where having a ball end rather than a straight end driver is really called for. I manage somehow but it isn't fun.?

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Hope this long reply helps and you figure out why you're getting this wear.??

On Tue, Feb 25, 2025 at 02:57 PM, <tshelley@...> wrote:

The mount does not seem to stop. The guiding will correct itself in 2-3 pulses after the 30 second phase and the mount continues to make drive noises. As far as did the mount receive a guide pulse, I don't know how to determine that. I know PHD2 produces a guide log that will tell me if it sent a guide pulse but I don't know of a corresponding log for the mount to tell me the mount received the pulse.

The mount does not seem to stop. The guiding will correct itself in 2-3 pulses after the 30 second phase and the mount continues to make drive noises. As far as did the mount receive a guide pulse, I don't know how to determine that. I know PHD2 produces a guide log that will tell me if it sent a guide pulse but I don't know of a corresponding log for the mount to tell me the mount received the pulse.

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Tim

Tim,

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The rebuild and regrease of the thrust washers and bearings is not that difficult. The hardest part is removing the motor to worm assembly and getting the worm tension right when putting it all back? together. Then just spin off the clutch knobs and lift the shaft up and out. Have a nice clean work area laid out for the parts where you can spread everything around for inspection and degreasing. I have found gasoline and brush is the best degreaser, followed by a rinse with JetSpray Gumout Carb Cleaner (handle the solvents with care with much ventilation and place any rags or wash pans outside to dry somewhere safe).

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If your washers have worn by that much, it's time to replace them. But I'm not sure that would cause any 30s delay which may be by something else. Does the mount just stop, or does it cease getting corrective guide pulses?

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John

_____________________________________________________________________________________________________________________________________________________________________________

Losmandy G11G2 on pier; refurbed Losmandy G11 with OnStep controller; SkyShed design roll-off observatory; ZWO ASI2600MM-P; ZWO ASI071MC; Sky-Watcher Esprit 100 ED with field flattener; Celestron C925 Edge HD with 0.7XFR, William Optics Zenithstar 61 APO; PHD2, NINA, Sequence Generator Pro and PixInsight user

John, thank you for the information. I appreciate it. I will put it to use with caution.

Chip, thank you for all the cautionary statements. I should have provided a more detailed account for why I was asking for this information. The reasons are 2 fold. I'm still having a random tracking issue where the mount doesn't correct guiding for an extended period of time, 30 seconds max. This is not a frequent occurrence but often enough that I feel the need to address it. The second reason is that the wear on the washers of the main axis thrust bearings is uneven. I discovered this when I was cleaning and re-greasing the mount. The last tear down I did was about 2 years ago. Now I did have Losmandy reconfigure the mount last summer to separate the RA and DEC axis for more portability. I asked that they inspect these bearings and replace them if necessary. They responded that the bearings were fine, the mount was essentially new. Admittedly my need for this information is based on my assessment of the bearing's condition, which could be in error. I observed that some portions along the inner radius of the washers were 1/3 to 1/2 of the thickness compared to the outer radius. There was some "waviness" of the inner edge of the washer forming. I do appreciate the need for detail on the bearing configuration. I also understand that dimensional mistakes could render the mount unusable. I really do appreciate the voice of reason reminding me that mistakes can be costly.

I have reduced the weight of my "kit" by about half and reduced the focal length of the main instrument by 40%. I would expect that this would have an impact on this guiding problem.

Apologies for the long winded reply, I know you are both busy.

Tim

Hi Tim,

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Following are the part numbers I have given out to folks in the past, but I have not checked the links in quite a while. There are the Losmandy stock parts (not sure why you can't get them) and others from McMaster and Amazon. I have switched to the heavier duty versions on my mounts which hold more grease and have caged bearings. Personally, I like using the replacement thrust washers mentioned over the stock part as they seem to have a higher hardness and should wear less.? I would also recommend replacing the worm bearings if you are going this far and which are also mentioned. You need the same set of parts for both the RA and Dec drives.

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Here are the upper thrust bearings:

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and one thrust washer:

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You need a one 1/16” or 0.06” thick washer (3 in. ID) and one 1/32” or 0.03” washer for the washer/bearing/washer stack to be the correct height for worm to ring gear alignment.

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And here is the thinner one:

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Some guys like this alternate bearing with caged needles instead:

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Losmandy sells the whole group as a set:

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but you should not need the inner donut which rarely goes bad. Smaller needle type bearings included here.

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3? ?? 5905K29??? ??? Needle-Roller Bearing, Open, for 1-1/4" Shaft Diameter
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1??? 94065K32??? Belleville Disc Springs for Ball Bearing Trade No. R4, 0.406" ID, Packs of 10
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2?????? SR4-ZZC #7 PS2?? BG (.250X.625X.196)
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Then there are the lower thrust bearings and washers as well (1.25” ID).

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or these alternates:

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with upper and lower washers both 1/32”, you need two.

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A lot of mounts came from the factory with Jet-Lube MP-50 applied to the upper thrust bearings and washers, and more importantly the ring to worm contact. The Jet-Lube Artic grease was applied elsewhere. Please let me know if you want some MP-50 as it is expensive and only comes in larger containers. I can send a small tin at cost with enough for a rebuild if you are in the USA.

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Please get back if you have any questions.

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Good luck,

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John

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_____________________________________________________________________________________________________________________________________________________________________________

Losmandy G11G2 on pier; refurbed Losmandy G11 with OnStep controller; SkyShed design roll-off observatory; ZWO ASI2600MM-P; ZWO ASI071MC; Sky-Watcher Esprit 100 ED with field flattener; Celestron C925 Edge HD with 0.7XFR, William Optics Zenithstar 61 APO; PHD2, NINA, Sequence Generator Pro and PixInsight user