Re: RA guiding awful after upgrade
Thomas,
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After the merdian flip the DEC and RA behaviors were consistent, about 0.5 arc sec. That is what you'd expect - seeing limited performance. People pay thousands more than you did to get that with absolute encoders and other things.
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But, before the meridian flip the RA was three times worse than the DEC. Notice also, that because the RA was much worse the max scale change from +- 8 arc sec before the flip to +-2 arc sec after,
making the DEC look much smoother pre-flip. But the DEC error value displayed was virtually the same before and after the flip, while the RA was much better after the flip.
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The post-flip performance is very good. But, because the data is only for a brief sample of time... It is possible that, by coincidence, the post flip captures were on a different part of the worm cycle. So, if you can, try to get the ASI Air to display 8 minutes of data, or take multiple, consecutive screen captures over 8 minutes with some overlap so you can see the full pattern. Do this with the scope on each side of the pier.
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The reason for eight minutes is that four minutes is the worm period of the G11, so by capturing 8 minutes (at least) of error data you can see multiple worm cycles.
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If that is too tedious then, go the PhD2 route and inspect the logs as suggested. But do so over two full worm cycles at the minimum; eight minutes or more. Your choice.
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If it turns out that the pre- and post-flip behavior shown in these four graphs (postings 83492 and 83493) is replicated across multiple worm cycles then the problem has something to do with cable drag, mechanics of how the mount is connected to your pier, or something that is orientation dependent (balance, whatever), not the mount and drive itself.
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Hope you get plenty of clear weather to work on this.
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Mark Christensen
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Re: RA guiding awful after upgrade
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I'm sorry to hear of these problems.? So your guiding problems started after the installation of new parts and the issue has been going on for months and so far nothing you have done since has changed the basic error rate??
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In the months since the mount upgrades have you changed your phone or O/S version, updated the ASIAIR app and ASIAIR hardware firmware, updated the Gemini 2 firmware or HC firmware?? Have you changed where the ASIAIR and Gemini 2 get power and is the ZWO ASI camera on its own 12V 5A power supply???
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The usual wosdom is that after changing out parts then having a new problem pop up is that you broke it by changing something.? Go back to the beginning and put it back to the way it was and retest.? I suggest uninstalling the RA extension first as it is the only moving part you repllaced assuming the pier is installed correctly and the fasteners are torqued down.? What brand of RA extension did you buy??
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Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Re: RA guiding awful after upgrade
On Wed, Jan 29, 2025 at 12:40 AM, Thomas Kallenbach wrote:
I have not used PHD2.? I've only used the asi air.? I don't know if the air produces a detailed log.
Hi Tom,
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You will need to connect a laptop to your mount to run PHD2. The guide logs then appear in the Documents folder, which is what is needed. The apps I mentioned will only work with PHD2 files as far as I know. But PEMPro Log Viewer and PECPrep already know the typical errors associated with a Losmandy mount - 239s for the worm period, 76s for the bearings, 32s for the gearbox, etc. So, they will tell you the magnitude of these errors and which is contributing the most. How to dig this info out of an ASI Air, perhaps someone else will jump in with the technique. Most likely you jostled something in the drivetrain when you reassembled the mount. You may need to reseat the worm gear or potentially compress the worm blocks a little bit.?
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But if you mount is guiding better on one side of the meridian than the other, you may want to go more east heavy with scope in RA so it will take up the backlash a bit more. This would mean sliding your counterweights up the shaft a little bit.
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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
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Re: RA guiding awful after upgrade
John,
I have not used PHD2.? I've only used the asi air.? I don't know if the air produces a detailed log.
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On backlash it makes no difference to how well the mount gets adjusted, the Losmandy mounts were designed with some slack in the system. It is just slack that needs to be taken up before anything happens, sort of like a 2-stage trigger. Nothing happens in the slack space or backlash just like a 2-stage trigger.? But just like a 2-stage trigger once the slack is taken up mount movement begins or the gun goes bang.?
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A good practice is to try to approach the ideal position from one direction much like an experienced SCT user will always focus by pushing the mirror up hill.? Once the desired position is achieved with adequate preload the mount won't move before the locks are snugged down.? This is the best practice with any Losmandy mount.?
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Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Re: RA guiding awful after upgrade
Hi Tom,
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How an ASI Air records the guiding data and how it could be used to diagnose RA errors is not something I am familiar with. However, if you can do some guiding with PHD2, that would provide some useful information. You can view the night's guide data with PEMPro Log Viewer , PHD2 Log Viewer or PECPrep to view the period of the errors and what mount components may be involved - worm, gearbox, etc. Addition of your extensions is most likely not the cause of poorer RA performance. But you may have jarred something else, and the worm tension may need to be reset. Analysis of guide logs can narrow this down to the mechanical component. Are you able to use PHD2?
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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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Re: RA guiding awful after upgrade
This is after the meridian flip.?
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Re: RA guiding awful after upgrade
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Re: RA guiding awful after upgrade
On Tue, Jan 28, 2025 at 10:38 PM, Thomas Kallenbach wrote:
Paul,
I took a couple of screen shots of what is happening tonight.
Tom, i do see the jumps, but it's hard to see when or why they happen from a screen shot. Can you capture some autoguider logs (text) showing the position error, and corrections? Don't know if you can get that from ASIAir.
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Re: RA guiding awful after upgrade
Paul,
I took a couple of screen shots of what is happening tonight.
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Re: RA guiding awful after upgrade
Tom, how does the autoguider calibration look compared to before? Does it take RA and/or DEC more time to reverse direction? If dithering takes a lot longer now, I start suspecting increased backlash (due to worm/gear mesh being too loose) or, alternatively, some stiction which is the result of a tight worm mesh.
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If you run a calibration, and then record some autoguiding logs, it may help to post them here for others to take a look. It may show when and why some of the large RA jumps appear.
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Regards,
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? -Paul
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On Tue, Jan 28, 2025 at 05:26 PM, Thomas Kallenbach wrote:
John and Paul,
Thank you for the replies.? Apparently I don't have notifications enabled so I just saw your messages.
My balance is good and I do a new polar alignment and calibration every night because it only takes a few minutes.? This problem has been happening for several months now, but we have had clouds for two months so I hasn't been a big deal.? Two months ago, I tightened all the screws and waited for a clear night to try it out.??
I thought about taking both extensions off and trying it again but that seems like a lot of work.? I am using one , 21 lb (I think it is) CW located about halfway up the shaft.? I think I tried using the 7 lb and 21 lb closer to the mount to reduce the moment but as I recall, they were too heavy even close to the mount.?
In the past I balanced the scope without regard for it being east-heavy.? Last night I adjusted the CW slightly so that it would be east-heavy.? No difference.? The DEC runs around .3-.7 by the RA is all over the place.? Sometimes it will be very good, then all of a sudden it spikes above the x-axis.? Then it spikes below the x-axis.? Dithering used to take very little time but now it takes a long time to return to stable guiding.??
Paul, how would the worm gear have been affected?? What should I check?
Tom
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Thanks Paul.? I had notifications off.? I apologize.
Tom
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Re: RA guiding awful after upgrade
John and Paul,
Thank you for the replies.? Apparently I don't have notifications enabled so I just saw your messages.
My balance is good and I do a new polar alignment and calibration every night because it only takes a few minutes.? This problem has been happening for several months now, but we have had clouds for two months so I hasn't been a big deal.? Two months ago, I tightened all the screws and waited for a clear night to try it out.??
I thought about taking both extensions off and trying it again but that seems like a lot of work.? I am using one , 21 lb (I think it is) CW located about halfway up the shaft.? I think I tried using the 7 lb and 21 lb closer to the mount to reduce the moment but as I recall, they were too heavy even close to the mount.?
In the past I balanced the scope without regard for it being east-heavy.? Last night I adjusted the CW slightly so that it would be east-heavy.? No difference.? The DEC runs around .3-.7 by the RA is all over the place.? Sometimes it will be very good, then all of a sudden it spikes above the x-axis.? Then it spikes below the x-axis.? Dithering used to take very little time but now it takes a long time to return to stable guiding.??
Paul, how would the worm gear have been affected?? What should I check?
Tom
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On Tue, Jan 28, 2025 at 05:10 PM, Thomas Kallenbach wrote:
Hello,
I was wondering if my recent question has been approved for the forum.
Thanks,
Tom
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It has and you¡¯ve already received a couple of suggestions:
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Hello, I was wondering if my recent question has been approved for the forum. Thanks, Tom
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Re: RA guiding awful after upgrade
After making any mod like this you should do a new polar alignment, a new PEC curve (if you do that), and a new guiding steps calibration. Also make sure you are still balanced and redo carefully. The extensions themselves should not cause an issue.? Also be careful to not to judge guiding from one night's results as seeing could have a big impact.
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Regards.
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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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On Mon, Jan 27, 2025 at 02:22 PM, Michael A. Covington wrote:
Where does one get the kind of washer you recommend?
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On Jan 27, 2025, at 16:33, Chip Louie via groups.io <chiplouie@...> wrote:
[Edited Message Follows]
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The use of flat thrust bearings is really not needed, there should never be that much force on the lock knob/lever.? If you really feel compelled to mess with the adjustment locks a good cheap compromise modification is to put a ground SS washer under each of the lock knob/lever with a thin plastic washer between the new SS washer and the GM8 or G11 base.? This promotes easier adjustment movement while reducing the undesirable mount movement when the knobs start to get snugged down.?
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I mention using a precision ground SS washer because they will introduce less movement during tightening of the lock knob/lever.?
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Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Any good hardware store will carry flat ground washers as well as various plastic washers.? Use a slippery plastic, like most types of polyethylene, PTFE or in a pinch I've cut slippery washers from white plastic gallon milk jugs LOL.?
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Also McMaster Carr has these parts as well as nice adjustable handles and knobs to substitute if that's your thing.? But like I mentioned previously it takes minimal torque to reliably hold the elevation or azimuth adjustments.??
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Backlash has nothing to do with the force needed to hold the adjustment.? You should have enough preload on the locks to just hold the mount during the time you use the adjusters.?
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Think of this as two are two different operations, adjustment and locking that unfortunately interact slightly when the locks are applied.? Using ground washers with low friction plastic washers is cheap and more effective than using a thrust washer alone as they remove much of the cause of shift in the adjustment.??
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This little change works for both the old original type adjustment locks where the knob holds the threaded rod and the newer fixed stud used with a knob with a threaded insert type adjustment locks.?
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Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Re: RA guiding awful after upgrade
Hi Tom, hard to tell what¡¯s changed in your setup, but I¡¯d at least check the balance in Dec and RA and make sure the additional hardware hasn¡¯t affected the worm/gear mesh.
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Regards,
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On Tue, Jan 28, 2025 at 12:49 AM, <Tjkallenbach@...> wrote:
Hello,
I bought an RA extension and 12" pier extension for my g11.? The goal was to improve meridian flips with my 130mm refractor. I checked all the screws in both components and they are tight.??
Guuding was good before the extensions .3 to .7 I. Both RA and DEC.? Now, DEC is still good, right now it's 0.4 but RA is 1.5, 1.8, 2.2 or more.? Last light after the flip it improved.? Tonight I moved the CW to make it east heavy.? That did not really help.? I have tried adjusting the aggression but that doesn't make much difference (I use an ASIAIR).? Again, the problems started with the new RA and pier extensions.? I hate to lose the first clear nights in two months so any suggestions are appreciated.? ?
Tom
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RA guiding awful after upgrade
Hello,
I bought an RA extension and 12" pier extension for my g11.? The goal was to improve meridian flips with my 130mm refractor. I checked all the screws in both components and they are tight.??
Guuding was good before the extensions .3 to .7 I. Both RA and DEC.? Now, DEC is still good, right now it's 0.4 but RA is 1.5, 1.8, 2.2 or more.? Last light after the flip it improved.? Tonight I moved the CW to make it east heavy.? That did not really help.? I have tried adjusting the aggression but that doesn't make much difference (I use an ASIAIR).? Again, the problems started with the new RA and pier extensions.? I hate to lose the first clear nights in two months so any suggestions are appreciated.? ?
Tom
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I don¡¯t have a lot of experience with mounts since I¡¯ve only owned two Losmandys so, I have no idea what a great adjustment system looks like or how they work ;). However, on both my mounts the Alt knob is quite good with no perceivable backlash. The AZ does have perceivable backlash but it¡¯s easy to work around it. The idea is to work from just one side so, if you are east of the pole and need to move west, move the knob a little in that direction and, the closer you get to a good PA the less you turn the knob so that you don¡¯t go past the pole. Presumably, if you happen to go past it, it will be by a negligible amount and you can leave it like that.
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If you use digital means of PA the process is quite easy and quick. If you do a drift alignment it can take quite a while because of the necessary small movements needed to prevent switching direction, and the slow nature of the procedure to begin with
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My 1.5 cents (not enough info to make up the entire 2 cents lol)
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Jonathan
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Chip Louie
Paul Kanevsky
