Re: Unable to fully lock RA axis on G11
On Fri, Feb 7, 2025 at 08:41 PM, <avishekaiyar@...> wrote:
Hello All?
?
I am a brand new user of Losmandy mounts. My past experience with GEMs has been limited to the iOptron SGP and the Vixen GPDX.?
?
I recently acquired a Celestron Losmandy G11.?
?
I tried to counterbalance my setup today and had a clarification about the RA axis.?
?
No matter how much I tighten the RA clutch knob I am unable to fully lock the RA axis movement (and I really tightened the clutch). The Dec axis is fine....I am able to fully lock down that axis when I tighten the Dec clutch.?
?
Is this normal ? As an example when I deliberately throw the RA axis off balance by moving the 11lb counterweight all the way towards the end of the shaft, the mount easily rotates about the RA axis even when fully tightened down.?
?
This has definitely not been my experience on the other gems I have used...
?
Would appreciate any advice.?
?
Sincerely?
?
Avi?
?
Do you recall the scene in Star Wars when Luke is introduced the his father's lightsaber?? The core of the Losmandy mount design is a lot like that lightsaber.? The G11 and GM8 were designed in a more civilized age, from a more elegant time.??
?
When the G11 was designed we used to be able to see the sky and learned how to navigate it.? Everyone learned the night sky and used the Thomas Bros. Map book of the sky called Sky Atlas 2000.? There were no GOTO "blasters" there was only personal knowledge and the skill needed to PUSH-TO your chosen object.? The original Losmandy Digital Drive simply moved the RA axis in sync with the local system and galaxy and you pushed the scope to your destination.?
?
To do this you needed a well designed, finely tuned machine and the mount needed to be well balanced with the scope in the saddle.? We ran the clutches fully or almost fully open / loose and used a finger or two to push the telescope tube to the desire object using personal knowledge and skill.? There was no need to lock the axis, this was simply unnecessary.?
?
With the advent or the Gemini and GOTO becoming the more widely used method of observation people with less skill could navigate the night sky once the learned some simple skills to align the mount with the night sky.? The advent of the GOTO computer brought many new observers to the hobby and the lack of knowledge caused a lot of frustration among the novices.? Those who couldn't or wouldn't adapt and invest the the time to learn these small skills usually left the hobby.??
?
There is no reason to cinch down the clutches on a Losmandy mount for GOTO or imaging use, none.? The only catch is the mount has to be in good mechanical condition (well adjusted, clean and lubed), the payload balanced in the saddle on 3 axis and you can not have any cable snags.? If your Losmandy mount meets these simple conditions it will guide very well, easily sub 0.5" error with only modestly snugged clutches.??
?
--
Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
?
?
?
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Are you using the same cord when switching power supplies? Short might be in cord.
?
The LittleFuse 452-454 (Fuse F1) is just to the right of the power connectors but would not short the power supply on failure.
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If your power cord has an automotive lighter plug , some have a fuse located in the metal tip but again this wouldn't cause a short.
?
I really think the cord is the prime suspect as the F1 fuse would prevent a shorted board from killing the power supply
?
Good Luck
Brian
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Re: Unable to fully lock RA axis on G11
On Sun, Feb 9, 2025 at 12:24 AM, <avishekaiyar@...> wrote:
I just separated the RA and Dec axes and disassemble the RA assembly (remove spacer, wavy washer, 3 piece thrust bearing and finally the RA shaft).?
?
Everything checks out. The clutch pad looks in a really good condition too.?
?
If I had to really nit pick, I would say that the wavy washer has lost a lot of its waviness. :)?
?
But after reading some of the other comments, I sort of see the point. With the Dec axis removed, the RA movements are pretty "locked" when the RA clutch is tightened (I made sure not to over tighten....I tightened it and let go as soon as I felt some resistance ). So I think it's ok.?
?
I also saw in one of the Losmandy balancing videos, Brian Valente also mentioning that the Dec axis is a lot "freer" compared to RA..I felt the exact same way so I guess it's all design intent.?
?
Hi Avi,
?
The locks never absolutely grip things down without movement. There is still a little play if you turn them hard enough. So the scope will move a bit if you bump into it or if it is very unbalanced or starts to drag a cable. I gave up on the wavy washer and balance RA by cranking ALT down to 0 (but careful you don't tip over if trying that). You could try new discs anyway or try the Michael Herman high friction discs, as Derek mentioned). Getting enough stiction for a night's operation should not be a hard thing.
?
Good luck.
?
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
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Re: Unable to fully lock RA axis on G11
Hi Derek,?
?
That makes sense.?
?
Thanks for pointing that out?
?
Avi?
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Re: Unable to fully lock RA axis on G11
Dear John?
?
I just separated the RA and Dec axes and disassemble the RA assembly (remove spacer, wavy washer, 3 piece thrust bearing and finally the RA shaft).?
?
Everything checks out. The clutch pad looks in a really good condition too.?
?
If I had to really nit pick, I would say that the wavy washer has lost a lot of its waviness. :)?
?
But after reading some of the other comments, I sort of see the point. With the Dec axis removed, the RA movements are pretty "locked" when the RA clutch is tightened (I made sure not to over tighten....I tightened it and let go as soon as I felt some resistance ). So I think it's ok.?
?
I also saw in one of the Losmandy balancing videos, Brian Valente also mentioning that the Dec axis is a lot "freer" compared to RA..I felt the exact same way so I guess it's all design intent.?
?
Thanks.
?
Avi?
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Re: Unable to fully lock RA axis on G11
It’s
not supposed to “fully” lock!.. I have Michael Herman’s high friction clutch
discs and a perfectly working G11 and with enough force, it’ll move..
It
doesn’t take much force on the knobs to sufficiently tighten the clutches..
Derek
?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of John Kmetz via groups.io
Sent: Saturday, February 08, 2025
7:50 AM
To: [email protected]
Subject: Re: [Losmandy_users_io]
Unable to fully lock RA axis on G11
?
Chances are your clutch discs are very oil and/or severely worn. You
will need to unscrew the clutch locks all the way off and pull the shaft up and
out of the mount to inspect. Remember the order of the knob, washers are
bearings and put back in the same order. Try wiping down the disc pad with
alcohol or some other solvent. If the discs are worn like a phonograph record,
they may need to be replaced. You can give them some extra life by doing a
light sanding and again wiping clean. You will need to clean the respective
upper and lower contact surfaces as well. But I would suggest ordering new ones
from Lomandy if they are really worn. This should give you some extra stiction
and allow the locks to grip down on something less slippery.
_____________________________________________________________________________________________________________________________________________________________________________
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
|
Not much I can say except send it for repair with motors, cables and HC. ?Hard to say what the issue is atm but in general they can be repaired?
?
cheers
--
Brendan
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Yesterday I was balancing my 2008 Losmandy G11, Gemini-1 using servo-motor current draw to fine tune the balance. At one point I used the hand controller to move the telescope to point at the celestial pole with counterweight down. As it neared that position the mount gave a continuous tone like when a safety limit is reached. That was puzzling since it wasn't anywhere near the limit. So I switched the Gemini-1 off, thinking it just needed a reboot.
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When I turned it back on there was no response, no startup beep, no lights on Gemini electronics chassis or hand controller. Then I saw the 17-volt power had no lights. So it seemed the power supply had died. So I brought out my old Pyramid 13.8 volt power supply and hooked it up. It too had the same symptom - when Gemini-1 was switched on, the power supply lights for voltage and current went off.
?
So two power supplies had same symptom - not supplying power with all lights on or connected to the Gemini-1 all lights go off. It's clear the problem lies with the Gemini-1, perhaps something like a dead short. I'll give another try today to see if a day's rest has corrected the problem. But the prognosis isn't good. Does anyone know if there is something that I can do, like a resettable circuit breaker or fuse?
?
I'll be contacting Michael Herman to see if he can resurrect my old Gemini-1. If that fails, perhaps buying a used Gemini-1 or new Gemini-2 would be the path forward. My 17 year old Losmandy G11 has been a stalwart in my astronomy adventure. It now resides inside Ocean Observatory, with slide off roof.
?
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Presently the G11 is carrying a Celestron-8 with AT115EDT triplet refractor, like what is shown below.
?
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So as can be expected, I'm eager to get my old Losmandy G11/G-1 back in service.
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Best Regards,
Russ
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Re: Unable to fully lock RA axis on G11
Hi John?
?
I will take a look right now and report back.
?
Thanks.
?
Avi?
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Re: Unable to fully lock RA axis on G11
Avi,
?
Chances are your clutch discs are very oil and/or severely worn. You will need to unscrew the clutch locks all the way off and pull the shaft up and out of the mount to inspect. Remember the order of the knob, washers are bearings and put back in the same order. Try wiping down the disc pad with alcohol or some other solvent. If the discs are worn like a phonograph record, they may need to be replaced. You can give them some extra life by doing a light sanding and again wiping clean. You will need to clean the respective upper and lower contact surfaces as well. But I would suggest ordering new ones from Lomandy if they are really worn. This should give you some extra stiction and allow the locks to grip down on something less slippery.
?
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
|
Re: Unable to fully lock RA axis on G11
On 2/7/2025 11:41 PM, avishekaiyar via groups.io wrote: No matter how much I tighten the RA clutch knob I am unable to fully lock the RA axis movement (and I really tightened the clutch). The Dec axis is fine....I am able to fully lock down that axis when I tighten the Dec clutch. The clutches are just that.... friction clutches.? If any grease has made it onto the friction surfaces (and it will) they cannot be "locked".? NOR SHOULD THEY.? The more you tighten the clutches the more load you put on the thrust bearings.? The thrust bearings use cylindrical rollers that roll in a circle.? And if you think about the geometry of a cylinder rolling in a circle, it will be obvious that it CAN'T unless one end or the other slips.? And if they slip unevenly, you can get RA jumps.? So the tighter the clutches, the more drag and unevenness from the rollers. Once I realized this I tried running with very loose clutches and all my RA jumping went away.? I don't know if it made a difference but I also cleaned the thrust bearings and re-greased with MP-50 since in essence, the rollers are a high pressure sliding interface.? I normally tighten until I feel contact and then go a maximum of 1/8 to 1/4 turn farther.? But, I can even run with the RA clutch fully loosened..... the rig is well balanced (that is key) and simply the weight of the rest of the mount and load is sufficient to provide enough friction. My $0.02 anyway. Paul (another one) -- Paul Goelz Rochester Hills, MI USA pgoelz@... www.pgoelz.com
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Re: Unable to fully lock RA axis on G11
Hi Paul
?
This is super valuable. I will try to take a video tomorrow and share it but based on what you are saying I think the mount is functioning normally.?
?
The clutches do hold the telescope. But as you said, if the load isn't properly balanced, it no long holds it in place.?
?
But I definitely feel that that Dec axis "holds" better than RA.?
?
Many thanks.
?
Avi?
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Re: Unable to fully lock RA axis on G11
Avi,
It is difficult to judge without seeing what you are doing.
You should always be reasonably balanced, the clutches are not designed to hold an unbalanced setup.
You should not tighten the clutches more than necessary, they are designed to be tightened by hand and should hold the telescope but if you knock it they may slip.
The clutches do not lock the mount axes, they hold them.
If you are easily able to move either axis it may indicate that grease has made its way onto the clutch plate(s), which would require a partial strip down and clean.
toggle quoted message
Show quoted text
On 8 Feb 2025, at 3:41?pm, avishekaiyar via groups.io <avishekaiyar@...> wrote:
Hello All?
?
I am a brand new user of Losmandy mounts. My past experience with GEMs has been limited to the iOptron SGP and the Vixen GPDX.?
?
I recently acquired a Celestron Losmandy G11.?
?
I tried to counterbalance my setup today and had a clarification about the RA axis.?
?
No matter how much I tighten the RA clutch knob I am unable to fully lock the RA axis movement (and I really tightened the clutch). The Dec axis is fine....I am able to fully lock down that axis when I tighten the Dec clutch.?
?
Is this normal ? As an example when I deliberately throw the RA axis off balance by moving the 11lb counterweight all the way towards the end of the shaft, the mount easily rotates about the RA axis even when fully tightened down.?
?
This has definitely not been my experience on the other gems I have used...
?
Would appreciate any advice.?
?
Sincerely?
?
Avi?
|
Unable to fully lock RA axis on G11
Hello All?
?
I am a brand new user of Losmandy mounts. My past experience with GEMs has been limited to the iOptron SGP and the Vixen GPDX.?
?
I recently acquired a Celestron Losmandy G11.?
?
I tried to counterbalance my setup today and had a clarification about the RA axis.?
?
No matter how much I tighten the RA clutch knob I am unable to fully lock the RA axis movement (and I really tightened the clutch). The Dec axis is fine....I am able to fully lock down that axis when I tighten the Dec clutch.?
?
Is this normal ? As an example when I deliberately throw the RA axis off balance by moving the 11lb counterweight all the way towards the end of the shaft, the mount easily rotates about the RA axis even when fully tightened down.?
?
This has definitely not been my experience on the other gems I have used...
?
Would appreciate any advice.?
?
Sincerely?
?
Avi?
|
Re: RA guiding awful after upgrade
On Fri, Jan 31, 2025 at 03:00 PM, Thomas Kallenbach wrote:
I appreciate your comments and no, I am not looking for perfect guiding.? What is the saying...The perfect is the enemy of the good.? I did have one thought; could the camera fan, if it is out of balance cause the problems I am experiencing?? I seem to remember hearing that some 2600MM cameras had fan vibration problems.? If that is possible I can swap cameras and see if there is a difference in the guiding.? What do you think?
Hi Tom,
?
I did the fan change on the 2600MM and I can't say it ever improved any of my images. But I don't think that would affect guiding on one side of the meridian versus the other. It sounds like you got a mount with low mileage so it most likely was set well at the factory. But there is no way to judge guiding performance until you actually get it out under the stars. Perhaps your mount got jarred during handling or transportation. But back to the worm gear - each one made at HGM is unique and has its own profile/personality even though they pass QC inspection. Sometimes you can get lucky swapping the RA and Dec worms to get better performance.? The RA worm is always turning and will wear more quickly than the Dec worm which just rocks back and forth. Once you have a very good polar alignment, Dec adjustments through a guide cam arrangement will be making only minor moves. So the latter will have a different thread wear which can serve for better RA tracking. The worms are made of brass and are easily bent on nicked when removed from the mount so be careful if trying this swap. As was already mentioned these mounts can be rebuilt more easily than other brands. You have something mechanical going on, so it all depends on how much you want/need to chase down the true cause.
?
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
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Re: RA guiding awful after upgrade
One thing from the comment Derek made, if I grab the CW shaft it will
move side to side slightly.
***
“slightly”
is good.. as in a 1/16th of an inch..
I
don’t use an ASIAir, but it sounds like things are “normal” so you should go
back to listening to the suggestions of others.. i.e. the same ones who taught
me.. Likely you will just do normal maintenance / learning what’s important and
it’ll work out.. The mounts are simple, but very well made and simple to work
on..
:-))
Derek
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Thomas Kallenbach via groups.io
Sent: Friday, January 31, 2025
8:36 AM
To: [email protected]
Subject: Re: [Losmandy_users_io]
RA guiding awful after upgrade
?
I contacted Losmandy but they weren't able to provide much help beyond
check for dragging cables.? I admit, the photos I sent do show a bit of a
cable mess but I am sure that is not the problem.? The scope had not been
used when I bought it, it was part of an estate sale (RIP) and didn't have any
nicks, scratches or blemishes.? Initially, I wrote to this forum because I
was having problems with the flips.? That was frustrating but was my
fault, not the mount.? The help I received here fixed my problem.?
?But, because the scope I bought this mount for (TS Optics Photoline 130)
is kind of long, I had to wait for the meridian flip to keep the scope from
crashing into the mount.? The extensions fixed that problem.? That
said, there are still several buggy aspects of the mount/asiair combination.
I am still a beginner.? I started with a Skywatcher EQ6 R a couple
of years ago so the Skywatcher is the only thing I have to compare to.? For
example, If I start a plan or auto run, the asiair will issue a goto to the
mount and the mount may or may not move.? The screen will indicate slewing
but the mount just sits there.? Other times the mount will move and get
stuck in auto-centering on the target.? It may indicate that the target is
centered but more often than not, I have to move it back to CWD shut everything
off and restart it.? ? Sometimes the mount/asiair has no idea where
it is and all of a sudden forgets where CWD is.? Meridian flips require at
least three commands from the asiair before the mount will move.? My guess
is the losmandy software and the asiair software do not communicate well
because the Skywatcher has none of these problems.? In my experience it
operates flawlessly.? And yes, all the software is up to date. It has been
cold recently but the RA guiding was bad in the warm weather.? I
understand that the G11 is in a different class than the eq6.??
One thing from the comment Derek made, if I grab the CW shaft it will
move side to side slightly.? Not at the connection of the shaft to the
mount but near the?
RA extension.? It is not much. It feels like slop in the gears.
But again it is not much but it is noticeable.? ?Derek, yes, I added
a 12 pier extension and RA extension at the same time.? Initially I
thought something was loose and that maybe I forgot to tighten a screw. I went
through it and made sure everything was tight.? I did not find any loose
screws.??
The mount still does a good job.? I had to toss a few subs for
sure but here is 33 hours with the G11:
?[URL=https://astrob.in/n0hff5/0/][IMG]https://astrob.in/n0hff5/0/rawthumb/gallery/get.jpg?insecure[/IMG][/URL]
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Re: RA guiding awful after upgrade
Mark,
I appreciate your comments and no, I am not looking for perfect guiding.? What is the saying...The perfect is the enemy of the good.? I did have one thought; could the camera fan, if it is out of balance cause the problems I am experiencing?? I seem to remember hearing that some 2600MM cameras had fan vibration problems.? If that is possible I can swap cameras and see if there is a difference in the guiding.? What do you think?
Old...getting old is a drag but it beats the alternative.? I'm there too.
|
Re: RA guiding awful after upgrade
A tiny amount of wiggle in each axis is normal.
?
Without any "lash" (aka wiggle, slop, choose your word) in one position (location on the worm) there is risk that the gears will bind on another.
The center of the worm teeth pattern is never exactly (we're talking thousands here) at the center of rotation of the axis. Want that? Spend a lot
more money.
?
Most people overdo trying to get backlash out of their mounts. Usually a fool's errand, caused by their desire
for perfection without spending tens of thousands on a mount.
?
When I adjust mounts I always to try to be able to just feel the wiggle but not see it or hear it (at high speed).
The human hand is a very sensitive instrument as is the ear.
?
I seriously doubt that is your "problem". And if you are satisfied with the imaging performance that is all that really matters.
More than one person has created problems for themselves while chasing perfection.
?
The fact that the "problem" appears only on one side of that mount (so it seems) points to something with weight/balance, or cabling.
?
I run my G11 off of WiFi using OnStep normally. I occasionally use USB but then it goes directly from the PC to the mount controller and that isn't very often.
So usually I just have one USB 3.0 running to the camera which has a built in hub. The guider and (when used) focuser connect to that so there is only one wire
from the PC to the mount and one power line to the camera cooler/hub. The mount and the PC each have their own power source.
That way I don't have a lot of wires running around to trip over between the PC (on a small table) and the mount. And minimal wires to drag the OTA..
?
Just the advice of an old, old, dog.
?
Mark C
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Re: RA guiding awful after upgrade
I contacted Losmandy but they weren't able to provide much help beyond check for dragging cables.? I admit, the photos I sent do show a bit of a cable mess but I am sure that is not the problem.? The scope had not been used when I bought it, it was part of an estate sale (RIP) and didn't have any nicks, scratches or blemishes.? Initially, I wrote to this forum because I was having problems with the flips.? That was frustrating but was my fault, not the mount.? The help I received here fixed my problem.? ?But, because the scope I bought this mount for (TS Optics Photoline 130) is kind of long, I had to wait for the meridian flip to keep the scope from crashing into the mount.? The extensions fixed that problem.? That said, there are still several buggy aspects of the mount/asiair combination.
?
I am still a beginner.? I started with a Skywatcher EQ6 R a couple of years ago so the Skywatcher is the only thing I have to compare to.? For example, If I start a plan or auto run, the asiair will issue a goto to the mount and the mount may or may not move.? The screen will indicate slewing but the mount just sits there.? Other times the mount will move and get stuck in auto-centering on the target.? It may indicate that the target is centered but more often than not, I have to move it back to CWD shut everything off and restart it.? ? Sometimes the mount/asiair has no idea where it is and all of a sudden forgets where CWD is.? Meridian flips require at least three commands from the asiair before the mount will move.? My guess is the losmandy software and the asiair software do not communicate well because the Skywatcher has none of these problems.? In my experience it operates flawlessly.? And yes, all the software is up to date. It has been cold recently but the RA guiding was bad in the warm weather.? I understand that the G11 is in a different class than the eq6.??
?
One thing from the comment Derek made, if I grab the CW shaft it will move side to side slightly.? Not at the connection of the shaft to the mount but near the?
RA extension.? It is not much. It feels like slop in the gears. But again it is not much but it is noticeable.? ?Derek, yes, I added a 12 pier extension and RA extension at the same time.? Initially I thought something was loose and that maybe I forgot to tighten a screw. I went through it and made sure everything was tight.? I did not find any loose screws.??
?
The mount still does a good job.? I had to toss a few subs for sure but here is 33 hours with the G11: ?[URL=https://astrob.in/n0hff5/0/][IMG]https://astrob.in/n0hff5/0/rawthumb/gallery/get.jpg?insecure[/IMG][/URL]
?
?
?
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Re: RA guiding awful after upgrade
On Fri, Jan 31, 2025 at 01:55 AM, John Kmetz wrote:
You can buy a new high precision brass worm from Losmandy which may give you better results
That seems unlikely to help in this case. The RA Worm appears to behave well, with low error and low PE on the east side of the mount. It's still a good idea to measure the unguided worm performance, but I doubt replacing the worm will improve on what Tom is reporting. Adjusting the worm/worm gear mesh might help. And rotating the worm gear to a different section, as was suggested earlier.
?
Regards,
?
? ?-Paul
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Chip Louie
BrianH
Russell Milton
Paul Kanevsky