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Re: ES Losmandy G11 RA Backlash
Brian,
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? ? ? ? ? ? ? ? I wanted to share the screen so that you can have a better idea as to why I had chosen the numbers for guiding :D. I am attaching the phd2 log during which I ran the guide assistant. As for the guide speed the phd2 wizard automatically chose this value. I had good success with .4x speed but will try out .5 tonight and compare results. One small change was observed by me today morning - even after almost eliminating DEC play the mount seems to have? developed significant DEC play now. Is it possible that weather caused some compression or something? It did get chilly yesterday. I had just to change my exposures in phd2 from 2 to 3 and vice versa as the moonlight or something was really blowing up my stars. Only reducing the duration managed to help me atleast guide the mount little bit.
?
Sunil
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Re: ES Losmandy G11 RA Backlash
Hi Sunil Ah - i did not see a guiding assistant run there Screen captures aren't useful for analysis, if you can upload the log that included the GA run that would be great. Are you sure the log you previously uploaded was after this? The exposure time i saw was 1 second. Based on your previous log you uploaded, RA was performing under what you set for min move and there was no backlash compensation applied, so all the things I mentioned are still valid recommendations. also I would say your guidespeed is too low at 0.4x - you want to be at least 0.5x or higher Guiding Assistant is sometimes just a guideline, and in your case if you are looking for guiding better than what it recommended, you will need to tweak those settings On Sat, Dec 26, 2020 at 11:24 AM Sunil Bhaskar Bhaskaran <cyclops12321@...> wrote: Brian, --
Brian? Brian Valente portfolio |
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Re: ES Losmandy G11 RA Backlash
Mark, ?Your comment on Sunil having is clutches unlocked to transport got me?to thinking. I transport my G-8 into the Mojave Desert for?Bortle 1/2 imaging and never do anything to the clutches. Am I risking damage to my drive trains or anything?else by not releasing the clutches? The entire mount is a foam and?plastic box latched tightly shut. Thanks Tom? --- mjcw500@... wrote: From: "Mark Christensen" <mjcw500@...> To: [email protected] Subject: Re: [Losmandy_users_io] ES Losmandy G11 RA Backlash Date: Sat, 26 Dec 2020 07:08:53 -0800 Sunil, First reaction is that RA backlash should never matter when guiding: The scope should be slightly heavy eastward and the guide rate should be less than 100%. That way the RA never reverses and hence backlash is a complete non-issue. To debug the problem I suggest you turn off dither along with any other "feature" - when diagnosing problems the simpler the configuration the better. It may be the fact that you have dither turned on for both axes that is causing RA backlash to show up. Second reaction is, have you tried readjusting the RA worm? That needs to be done with the motor removed while rotating the worm by hand so you can see and feel what is going on. The worm wheel (large gear attached to the axis) needs to go through the full rotation so that you don't bind on the (unknown) high spot on the gear. Third reaction is, I hope for your sake than when you shipped it the clutches were loose! Best Wishes, Mark Christensen |
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Re: ES Losmandy G11 RA Backlash
Brian,
? ? ? ? ? ? ?All the values entered in the toolbar(except the Hysterisis) was recommeded by phd2. The one thing I gotta mention is that the weather here is a bit hazy so I was taking longer duration guide pulses (2s - 3s) I believe.I have enabled backlash compensation and ran guiding assistant. I am attaching calibration and guiding assistant info as well. |
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Re: ES Losmandy G11 RA Backlash
Mark,
? ? ? ? ? ?Appreciate the responses. The truth is I have been battling this issue for the past 8 months when I couldn't use the mount at all. Before that it functioned well. Not this bad. To answer you questions :? 1)RA Backlash : I apologize for the wrong methodology . I was referring to the worm wheel an the worm block wiggle. No matter how much I tighten, there seems to be movement when I wiggle the counter weight shaft. There is no DEC play but there is severe RA play. 2) I have tried adjusting but these seem to be very different from the traditional G11 worm blocks. No offence but the Gemini 2 ones look way better and sturdier than the one I have. The worm cover is just that - a cover. I I have seen videos from the Losmandy channel in youtube but the motor assembly is very different. While Gem2 is servo mine is stepper.WHen I tried to remove it, something was preventing it from coming off. Do I need to loosen the couplings which connect the motor to the worm mesh? 3) The mount worked fine for a while. But being in a humid and ununsed state took its toll I guess. The lube inside had solidified and I had to relube everything except the worm wheel. |
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Re: ES Losmandy G11 RA Backlash
HI Sunil Here's my observations from your guidelog looking at your two longest runs 1. your settings are not very optimized for your conditions and equipment. your min move on RA is too high, it's at 1" and you are guiding at 0.82" so i'd say for that min moves your guiding is where i would expect it. Run guiding assistant and/or set that value lower 2. your seeing looked less good in the second long run (segment 11), i think your exposure time should be longer to even that out - maybe 2.5-3 seconds 3.? you should enable dec backlash compensation in PHD which will clean up your DEC guiding. a guiding assistant run should make a recommendation there, but if not i would start with 800ms with a max of 2500ms and let it adjust itself 4. after tightening up min mov in RA (and DEC too), if you still need better guiding results you can try predictive PEC algorithm for RA. i'd set the period to 239.9 and disable auto adjust period.? that should be a good start On Sat, Dec 26, 2020 at 5:16 AM Sunil Bhaskar Bhaskaran <cyclops12321@...> wrote: Hi, --
Brian? Brian Valente portfolio |
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Re: ES Losmandy G11 RA Backlash
oop sorry i see it here in the op let me look at it On Sat, Dec 26, 2020 at 5:16 AM Sunil Bhaskar Bhaskaran <cyclops12321@...> wrote: Hi, --
Brian? Brian Valente portfolio |
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Re: ES Losmandy G11 RA Backlash
Hi Sunil >>>First reaction is that RA backlash should never matter when guiding: The scope should be slightly heavy eastward and the guide rate should be less than 100%. That way the RA never reverses and hence backlash is a complete non-issue.Mark is spot on here, RA backlash is a non-issue in guiding unless somehow you managed to get your guidespeed above 1x (which I don't think is possible) To diagnose further we'd need to see your guidelogs, and preferably a baseline guiding as defined in these steps: On Sat, Dec 26, 2020 at 7:09 AM Mark Christensen <mjcw500@...> wrote: Sunil, --
Brian? Brian Valente portfolio |
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Re: ES Losmandy G11 RA Backlash
Sunil,
First reaction is that RA backlash should never matter when guiding: The scope should be slightly heavy eastward and the guide rate should be less than 100%. That way the RA never reverses and hence backlash is a complete non-issue. To debug the problem I suggest you turn off dither along with any other "feature" - when diagnosing problems the simpler the configuration the better. It may be the fact that you have dither turned on for both axes that is causing RA backlash to show up. Second reaction is, have you tried readjusting the RA worm? That needs to be done with the motor removed while rotating the worm by hand so you can see and feel what is going on. The worm wheel (large gear attached to the axis) needs to go through the full rotation so that you don't bind on the (unknown) high spot on the gear. Third reaction is, I hope for your sake than when you shipped it the clutches were loose! Best Wishes, Mark Christensen |
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ES Losmandy G11 RA Backlash
Hi,
? ? ? I own a ES Losmandy G11 Pmc8 variant of the Gemini2 system and I seem to have some serious RA backlash issues. I tried to get help in the ES Pmc8 forum but I was told to approach the Losmandy group. The mount is around 3 years old and I recently lubricated it using Super Lube. Guiding seems to be all over the place and most of my subs are getting discarded by SGP. The mount worked fine when it was in US but now after relocating to India(shipped via freight), it seems to have developed some serious backlash issues. I managed to fix the DEC backlash to some extend but the RA seems to be a whole different story. Appreciate any help you guys can provide. The autoguider is qhy5ll on a 200mm finder. Attaching the phd2 log. Please let me know if anyother details are needed from my end. Sunil? |
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Re: First time using PHD2
Just an update from my guiding experiments with PHD2 on Christmas Eve.
I changed over to a ZWO 120 MM mini guide camera (and this calibrated quite quickly because it is USB3). By playing with the aggressiveness parameter in PHD2 I managed to get the RA RMS down to 0.8-0.9¡± and the RA Osc value to about 0.36. The DEC RMS value was slightly lower at about 0.7¡±. It all seems to be working now so hope to start doing some imaging now. On my first attempt with PHD2 the aggressiveness value was set too low. I am also planning to strip the G11 down and relubricate it, and may swap the DEC and RA worms to see if that improves the periodic error. |
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Re: Degreaser / Cleaner..
Sonny Edmonds
I'll weigh in on saying mineral spirits as a general cleaner.
Wear some chemical gloves so you don't strip your hands. Denatured Alcohol is a good rinse agent. Again, protect your hands, and a mask or goggles is prudent. If you ever get this stuff in an eye, you won't ever forget to wear your PPE again. It hurts like hell. And a small brush can put a little pecker of it in your eye. Then what? You've got it all over your hands and maybe arms. Make sure you get chemical resistant brushes and bottles, and if you borrow a kitchen pan, do not return it to the kitchen. You food will NOT taste good.... I would not use brake cleaner. Brake cleaner is really wonderful stuff. And it really cleans great. But I wouldn't want to Break my mount with Brake cleaner. ;^) But I think it is a bit harsh for your mount parts. So me, myself, and I, would advise to stay with the more elbow grease requiring solvents. And I like to work on the floor. The floor is my Friend. Nothing falls further than the floor (or driveway with a tarp under). Everything stops at the floor. Even bouncy stuff stops, eventually. Merry Christmas! -- SonnyE (I suggest viewed in full screen) |
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Re: Degreaser / Cleaner..
I have used simple mineral spirits for several different mounts without trouble.? It even dissolves the goo in Synta mounts.? I have only had to resort to brake cleaner once, for a mount with completely dried-out grease: no oil left at all.? The thickener was caked in the bearings tightly.
Be careful with brake cleaner, it is nasty stuff. |
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Re: Regreasing worms
I agree with John Kmetz: full disassembly.? In addition to getting all the old lubricant and grit out and adjusting the worm mesh on reassembly there is also the opportunity to degrease the clutch pads.? The grease eventually migrates everywhere.? SuperLube is the default recommendation of many on Cloudy Nights.
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Re: Pointing Mount To Zenith To Take Flats
Edward Beshore
Hi Jim
The Dec should be your latitude and the RA should be the current sidereal time, which is the current RA of the meridian. Do you have that available to you? Its a pretty simple calculation if not given your geographic coordinates and UT. |
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Re: Regreasing worms
Robert.Ian:
You know I just did this about a month ago and I did a full disassembly. I really wanted to get rid of the old lube and also any metal fines that accumulated when any two metal parts move against each other. Plus I had lube leakage into the clutches from the hot summer weather. If you ever have changed the oil on a new car, you may know the first drain is full of metal debris you don't want inside the engine. So I cleaned all the working parts with solvent and a brush, first gasoline then a final rinse with Brakleen.? Reassembly went well but I would have to advise that the final tuning of the worm blocks was time consuming and bit tricky. I would suggest viewing the Losmandy videos on this before trying anything. I am pretty mechanically inclined and have a master mechanics tool set and a pretty complete workshop, but the first time around for me was a bit involved. You need to pressure the worm inward and to the left to mate the worm and ring gears, and then back off just right with the adjustment screw to stop the motor from stalling. Leftward pressure closes the gaps between the blocks and reduces sideways motion. When Losmandy says they don't recommend this at home I can see why. It takes some experience to get it just right. Too loose and you have backlash, too tight and you stall. And the margin for error in between is quite small. You probably should do a PE analysis with PEMPro or PECPrep before any work to make sure you get back to the same PE you started with. I used the Teflon based Superlube, which is temperature resistant, and did a light coating around the whole ring gear and the worm too. The light hydrodynamic film should serve to ride over surface asperities and reduce any minor chatters. But the Teflon also serves as a barrier film to further separate higher pressure contacts. Losmandy uses that Jet-Lube MP-50 with molybdenum, which is probably overkill, but may serve to chemically react with the wear surfaces as an extreme pressure additive.? ? So a full disassembly is best for lubrication, but you may be in for a chore to retune the worm blocks if you remove the worm to do a deep clean. Good luck, John |
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Re: Jupiter-Saturn conjunction sequence (GM-8)
haha totally works! On Wed, Dec 23, 2020 at 10:26 PM Jamie Amendolagine <jamie.amendolagine@...> wrote: I took my wife and kids to the "sandy hills" trails nearby to see this. We only brought binoculars and a dslr so there was no hope of a fantastic view or shot, but we had a lot of fun. Here's the shot that I got, I call it HO HO HO! --
Brian? Brian Valente portfolio |
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Re: Jupiter-Saturn conjunction sequence (GM-8)
I took my wife and kids to the "sandy hills" trails nearby to see this. We only brought binoculars and a dslr so there was no hope of a fantastic view or shot, but we had a lot of fun. Here's the shot that I got, I call it HO HO HO!
https://photos.app.goo.gl/huQGHj8KNBdeRHMWA |
Jamie Amendolagine
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