On Tue, May 13, 2025 at 06:30 PM, Ray Gralak wrote:
The PEC ON log file shows that the mount's Declination was 89.9472, close to the celestial pole. This is a terrible place to measure periodic error, so the result with PEC ON is probably incorrect. You should run the calibration wizard with PEC enabled, which will offer to slew the scope to a good position in the sky.
Ray,? Once I clean and regrease the unit I will do another run and slew the mount again after the OFF run. I just ran the ON session straight after the initial OFF session without a slew - seems odd that it went that far.
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I double checked the PHD2 calibration slew and the mount did a meridian flip when the small push north step ran at the end of it's slew - seems there is a mount limit in affect.
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Thanks,
Ken
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On Tue, May 13, 2025 at 09:30 PM, Ray Gralak wrote:
The PEC ON log file shows that the mount's Declination was 89.9472, close to the celestial pole. This is a terrible place to measure periodic error, so the result with PEC ON is probably incorrect. You should run the calibration wizard with PEC enabled, which will offer to slew the scope to a good position in the sky.
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Good catch, Ray! I didn't notice that in the logs, but for sure, that's the worst place to measure PE. Celestial equator near the meridian would be a much better start :)
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Hi Jesse,
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My second G11 is a refurbed 1997 era mount with the OnStep conversion. Since yours is even older I would recommend replacing all bearings and thrust washers, even the needle bearings inside. You will need a bearing puller to get to these latter ones as it's near impossible to get any tool in behind them. From the pics you are showing, I assume you are wanting to replace the lower thrust washer assembly which goes in the following order - thrust washer, thrust bearing, thrust washer, spring washer, anodized donut, and finally the clutch knob. If you send me a PM I can give you a list of all the parts you need and where to get them. I also can supply a lubricants sampler, with enough original Losmandy greases to redo the mount.
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There may be nothing wrong with the original stainless worms, which I just reused on my mount. It all depends on their peak to peak error in arcseconds; mine were around 10-12. Between using PPEC in PHD2 and Howard Dutton's PEC correction tool, you get can your guiding errors down to pretty low numbers. My worm connects directly to the motor via a bellows coupler, with the right angle aluminum stock as already mentioned holding the motors in place. But you should also do some type of Belleville washer upgrade on the far side block to keep the bearings compressed and the 76s error to a minimum.?
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Please let me know if I can help further.
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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
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Hi Ken,
From your PEC ON log file:
# Declination # 89.9472
The PEC ON log file shows that the mount's Declination was 89.9472, close to the celestial pole. This is a terrible place to measure periodic error, so the result with PEC ON is probably incorrect. You should run the calibration wizard with PEC enabled, which will offer to slew the scope to a good position in the sky.
-Ray
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-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Oberon510 via groups.io
Sent: Sunday, May 11, 2025 10:42 AM
To: [email protected]
Subject: [Losmandy_users_io] PEC request
Hi,
I had cause to redo my G11G (with all latest firmware) PEC training and my OFF/ON PemPro logs seem to indicate
the PEC training was a success. The only problem is that my PHD2 Guiding Assistant logs (with tracking off)
show the periodic error is still there. I double checked PEC is enabled in the Gemini Telescope driver at startup.
Maybe I am reading something wrong so hoping someone could review the logs below for a second opinion.
There appears to be other things at play also but just hoping for an opinion on the PE work.
Thanks,
Ken
PS - BTW, how is the new Gemini PEC work progressing?
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Good Evening!
New to the group but not to Losmandy. I am looking into the G11T to mount my Meade 14 inch SCT (the non-ACF version) for both imaging and visual. I am going to guess around 70 pounds with all of the imaging and other accessories attached and with that number I am attempting to calculate the amount of counterweights that I need. I am figuring around 80 to 85 pounds (from my math) but another telescope site notes that all I need is 60% ( 45 pounds does not sound right) of the weight of the scope and accessories. Which number would be the closest to correct? This would help me decide how many extra counterweights to add to any future order. I have two 11 pound weights that I use with my current G11 (non-Gemini).
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One more: I would I need the MAL and the MAL to MA adapter to mount the G11T on the tripod that came with my G11? I do have the Meade Giant field tripod that came with the 14 inch. I do question the stability for imaging when compared to my Losmandy tripod.?
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Thanks for the help!
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Ken
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Re: DIY Spring Loaded Worms for the G11
Fantastic!! Thank you so much.?
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What an awesome set of modifications
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Re: DIY Spring Loaded Worms for the G11
On Tue, May 13, 2025 at 12:41 AM, Avishek Aiyar wrote:
Looks like attachments and pictures disappear after a certain period of time.?
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I would love to see the original attachments in these posts....is there a way to see them ??
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This group has a limit of 1GB of photos and attachments storage. When folks upload new images or send large attachments (sometimes large movies!), older attachments are removed to make space for new ones. The only way to get around the 1GB limit is to convert this group to a paid group, which will require an annual payment to be collected and paid to Groups.io. The other alternative is to share large files through an external file sharing service, rather than sending them as attachments (dropbox, google drive, etc.)
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Re: DIY Spring Loaded Worms for the G11
Hi Avi -
Hmmm.? ?Yeah, I dont see the original images here either now.
I'm not sure Ive got everything duplicated at cloudy nights, but this should be enough to give you an idea:
https://www.cloudynights.com/topic/769071-losmandy-g11-onstep-conversion/?p=11116588
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Re: DIY Spring Loaded Worms for the G11
Looks like attachments and pictures disappear after a certain period of time.?
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I would love to see the original attachments in these posts....is there a way to see them ??
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Thanks!
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Avi?
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Hi Paul,
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Thanks for the suggestions and I have ordered the clean/regrease kit from Losmandy to do some clean up work. I also adjusted the backlash on the Dec sprung worm gear to see if will clean things up before looking at swapping them over. I am getting some strange movements in Dec during the PHD2 calibration so something is amiss per your comment - will look into it more after the regrease work.
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I will also retry activities when the weather clears in a few days - on a night when the moon is not blowing out the tracking too.
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Thanks,
Ken
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A quick and easy fix for the alignment of the two-piece worm blocks is to get a piece of AL angle iron (about 3/4 to 1 inch on a side and check it for flatness
on one exterior surface with a good straight edge).? Do the initial install and gently clamp the angle iron to one of the worm blocks and then apply a clamp the second
worm block to hold it to the flat section of the angle iron. Use soft jawed clamps if you have them.
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Do not tighten the screw (one each) that holds the worm block in position just yet. Just make snug them down but not so much that the
block can't slide when you apply a little force.
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Then nudge the worm into worm wheel to adjust the mesh and rotate the worm by hand thru a full rotation to find the high spot on the worm wheel.
The center of the worm wheel gear tooth pattern and the center of rotation of the axis are never quite perfect unless you spend many thousands.
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If it binds you'll be able to tell it by the force you need to exert with your fingers.
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Set the backlash at the high point of the worm/worm wheel contact and carefully?tighten the two screws.
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When you're happy, remove the two clamps and the angle iron.
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Why do I keep saying "snug", "gently", and "carefully"? It is because the metal of the worm bearing blocks is thin and if you get too aggressive about
tightening those screws down you run the risk of distorting the worm blocks and hence stressing the little bearings (which you might want to replace
in any case). I know all this because when I got my G11 used (about the same vintage) it had horrible Periodic Error. To solve it I replace the worms
with the brass high precision ones, replaced the bearing blocks, and installed new bearings. The prior owner had overtightened everything on the mount
and it was impossible for me to get the little worm bearings out of the blocks. Replacing the blocks and the bearings also made the install of the new
high precision worms easy.
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The only pricey part of this is the high precision (brass) worms.
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This isn't a high vibration operation, so there is no reason for us to get too enthusiastic with a wrench. Likewise, many get too aggressive about eliminating
backlash in an attempt to achieve perfection. Want perfection? Plan on paying 10X.
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I found there was no need to lap worms or anything.
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By the way, make sure you use something like SuperLube low temp grease. Avoid any grease with graphite: With moisture graphite can, I am told, pit aluminum
and that is what the worm wheel is made of.
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Mark Christensen
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Welcome to the club.? Not quite the full package Losmandy G11 mount close enough.??
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The best couplers to use here are a constant velocity type coupler that is designed to be used with some axial and angular misalignment.? Read up on the different types and you'll find that the best couplers where you may have some of both a double disc coupler is superior.? They take up some room and cost more but they are the best type for this job.? Where there is no angular misalignment just axial the Oldham's are also the top choice.??
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All other miniature couplers have issues that can be an issue if precision constant velocity power transmission is required.? Do some research and you'll see this is true.??
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To improve your classic 2-piece Losmandy worm drive backlash situation the best and simplist things to do are to hone the closed worm bearing block to allow the outer bearing to float in the block.? That's to say the bearing is allowed to move in and out slightly.? Fit a single R4 size Belleville spring disc inside the greased bearing carrier pointy end facing away from the bearing so the base of the spring disc pushes on the outer bearing shell.? Load a new worm bearing in the bearing carrier push it in and verify the besring moves back out.?
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The other tip is to tie the bearing blocks together in perfect bearing alignment with each other using the worm dust cover to hold the worm bearing blocks in place.? Essentially this gives you a one-piece worm block which allows you to effectively set backlash and keep the worm bearings aligned without having to struggle with dumb luck to get enough pressure on the bearing blocks while trying to set backlash.?
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The two bits above work together to solve one of the two biggest issues with worm drives.?
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If you are talking about the small undersized clutch spacer rings those are somewhat proof your G11 is an older production mount.? Older mounts seem to have come with these smaller diameter clutch spacers.? There is no cover for the clutch thrust bearing stack these spacers are a part of.? The thrust bearings on both axes just live somewhat exposed.? The good news is that they are easy to remove and easy to clean and relubricate.??
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If you would like there are clutch spacer replacements that match the body of the mount diameter available for about $20 a pair.? Largely cosmetic but they may help reduce the amount of dust and grit that can settle on the thrust bearings.? ?
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There should also be a black anodized cap on the back of the RA axis to keep dust and critters out of the RA axis.? I can't make out from the images if it is there.? It looks like the threaded retaining piece for the polar scope is there instead.? If you don't have the polar scope replace the polar scope retaining ring an replace it with the black machined alloy RA axis cap.? If you are missing the cap replacements are available fairly inexpensively.??
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Good luck on your adventure.??
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--
Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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I've been looking to pick up an older G11 for a few years, with the idea to mount it on a permanent pier in my yard. I'm moving to a new house with hopefully darker skies, so now was the time.
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I asked for an older one and I'm pretty sure that's what I've got. No serial number on the bottom makes me think it predates the serial numbers, so maybe 1990-1992ish? It doesn't have the brass worms but I'd planned on installing new ones anyway. I've done a lot of OnStep builds so that's the plan here as well. I'll either buy the MA pier adapter or weld something up. The 'pier' is a 72 inch long 6" ID steel pipe I've been babysitting for years.?
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I know this mount had a 492 kit and motors of some kind installed previously. Half of the Oldham connectors were still on the worms, but I'll use bellows connectors for the gearing later.?
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Having never seen another G11 in person, I'm not sure what else to look for in terms of maintenance. I'll install new worms and worm block bearings after cleaning and regressing, then follow some guidance here on setting backlash until I'm frustrated enough to buy a OPW block or make my own.?
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Near the clutch knobs on each axis, it seems like there's a cover or piece missing, particularly when compared to other photos of G11 mounts I've seen. Any ideas?
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 ?
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Hi Ken,
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The PEMPro ON data appears to show a fairly large reduction in periodic error. There's a bit of a rotation error in the data, which may mean the PEMPro calibration wasn't as good as it could be. But overall, after derotating the data, worm PE was measured at less than an arcsecond. I can't tell what happened with your PHD2 guide log. There doesn't seem to be any improvement, but I would expect (from the PEMPro plot) that the improvement should be significant.
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There is something wrong with the worm or your measurement, despite PEC being able to correct for it. That large peak is very unusual, and well exceeds any other periodic error I've seen from Losmandy mounts. At the very least, I'd try to clean, regrease, and adjust the worm/gear mesh, but also, possibly swap the DEC and RA worms to see if you get a better result with another worm.
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On Sun, May 11, 2025 at 01:42 PM, Oberon510 wrote:
Hi,
?
I had cause to redo my G11G (with all latest firmware) PEC training and my OFF/ON PemPro logs seem to indicate the PEC training was a success. The only problem is that my PHD2 Guiding Assistant logs (with tracking off) show the periodic error is still there. I double checked PEC is enabled in the Gemini Telescope driver at startup.
?
Maybe I am reading something wrong so hoping someone could review the logs below for a second opinion. There appears to be other things at play also but just hoping for an opinion on the PE work.
?
Thanks,
Ken
?
PS - BTW, how is the new Gemini PEC work progressing?
?
?
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Hi,
?
I had cause to redo my G11G (with all latest firmware) PEC training and my OFF/ON PemPro logs seem to indicate the PEC training was a success. The only problem is that my PHD2 Guiding Assistant logs (with tracking off) show the periodic error is still there. I double checked PEC is enabled in the Gemini Telescope driver at startup.
?
Maybe I am reading something wrong so hoping someone could review the logs below for a second opinion. There appears to be other things at play also but just hoping for an opinion on the PE work.
?
Thanks,
Ken
?
PS - BTW, how is the new Gemini PEC work progressing?
?
?
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On Fri, May 9, 2025 at 01:26 PM, Kenn wrote:
Thank you Chip for your response. After searching the web for the Teflon Super Lube the closest I was able to see was?
Super Lube Silicone Lubricating Brake Grease with Syncolon (PTFE) - Food Grade; which I would assume is not the one you are suggesting I use. I'm not sure why anyone would want to eat the stuff.
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Locating Super Lube with Teflon is a bit difficult.
Kenn
Hi Kenn,?
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The trade name the Super Lube folks use for Teflon (PTFE) is Syncolon.? This used to be harder to find but now the stuff is even at Ace Hardware stores.??
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Here is a link to the product page with the correct grease:?
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I don't know where you are but Amazon has it here: .??
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--
Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Most Excellent...............I really appreciate your response and guidance.
Kenn?
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Old thread but hoping someone has picked up one of these commercial piers and could rate them. SkyShed is ~1/3rd the price of ATS. Maybe it is a steel vs aluminum cost decision.
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Thanks,
Ken
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Unless I am gravely mistaken, PTFE is Teflon.
On 2025-05-09 16:26, Kenn via groups.io
wrote:
Thank you Chip for your response. After searching the web
for the Teflon Super Lube the closest I was able to see was?
Super Lube Silicone Lubricating Brake Grease with Syncolon
(PTFE) - Food Grade; which I would assume is not the one you
are suggesting I use. I'm not sure why anyone would want to
eat the stuff.
?
Locating Super Lube with Teflon is a bit difficult.
Kenn
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Michael A. Covington, Ph.D.
Consultant, Covington Innovations, Athens, Georgia, USA
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Thank you Chip for your response. After searching the web for the Teflon Super Lube the closest I was able to see was?
Super Lube Silicone Lubricating Brake Grease with Syncolon (PTFE) - Food Grade; which I would assume is not the one you are suggesting I use. I'm not sure why anyone would want to eat the stuff.
?
Locating Super Lube with Teflon is a bit difficult.
Kenn
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Paul Kanevsky
Chip Louie
Kenn