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Re: RA axis movement or wiggle

 

Because it's spring-loaded, you'll see a lot of wiggle if you push moderately hard, but that doesn't mean you have that much backlash during normal tracking.
Re: RA axis movement or wiggle

 

Even with this backlash, how is your guiding ?? ?Backlash in RA is not a big thing as it tends to guide in one direction most of the time.??

Regards,
Daniel
RA axis movement or wiggle

 

How much wiggle or movement should there be for the RA axis if the spring-loaded worm and secondary screw are adjusted correctly?? ?I measured the movement of the far end of the counterweight shaft and found 3mm of movement.? This seems excessive.? ?I had less movement but was forced to back off the secondary screw because the RA motor was stalling.? ?Is there something else other than the secondary screw that might be causing/contributing to this 3mm of movement?? ?Is there anything different about adjusting the secondary screw for the RA axis compared to the secondary screw for the DEC axis?? ?The DEC axis had some movement and I was able to significantly reduce it by adjusting the spring-loaded worm and secondary screw for DEC.? ?My mount is a GM811G and is about a year old.? ?I use it a lot, about 130 nights of imaging/testing since purchase.? ?Thanks in advance for any advice.? ? --? Jim?
Re: Resetting spring-loaded worm

 

Danial, please post your PHD2 log file and I'll look at it for glues.

Peter
Re: Resetting spring-loaded worm

 

The spikes I mention can be seen in this excerpt of a PHD2 log:



As you can see the error is most of the time in a band of +-1", but there are occasional spikes. Even without the occasional spikes, I do not like too much the performance, too much oscillations with just 9 lbs of equipment (Sharpstar 76EDPH with all the typical add-ons).? With the 343mm focal length of the 76EDPH? the resulting images are perfect, but? I would like to be able to image with longer instruments (with 1200mm fl as the maximum perhaps).?

I think that oscillations could be related to stiction and may benefit from a fine adjustment of the worm gear.

Best regards,
Daniel
Re: rehab a G11

 

Bob,?

This depends on the total age of the scope, not just idle time. Sitting for 3 years might make the lubes drip through a bit, especially with higher temps. So we know the mount is 3 years + at this point.

If only that old, you can do the basic clean up and relube as in the videos, plus replace or clean the clutch discs which may be worn or oily. If the scope is 5 years plus, you may want to do a full teardown, degrease and relube, but also replace some moving parts like the Oldham couplings, gearboxes and the worm bearings. The thrust bearings and washers should also be inspected at this time as well.

The greases do move away from the gear surfaces with use, and also trap in dust and metal fines from the gears wearing. But make sure to replace with quality lubes like the Jet-Lube MP-50 on the worm and rings, and Jet-Lube Artic or other surfaces (which are the original Losmandy lubes). But I would recommend Mobilgrease 28 over the Artic, as this aircraft-rated grease has very good anti-wear properties.

Wish I could help but I am over 3000 miles away. As mentioned, resetting the worm to ring tension takes some time and patience, if you don't have a Losmandy knowledgeable helper close by.

Regards,

John
___________________________________________________________________________________________________________________________________________________________________________

Losmandy G11G2 on pier; SkyShed design roll-off observatory; ZWO ASI2600MM-P; ZWO ASI071MC; Sky-Watcher Esprit 100 ED; Celestron C925 Edge HD with 0.7XFR, William Optics Zenithstar 61 APO; PHD2, Sequence Generator Pro and PixInsight user
Re: Resetting spring-loaded worm

 


PE spikes can be caused by stiction which may be visualized as force ramping upward with a sudden release as the level of force applied overcomes the resistance present. There are two possibilities here, the bottom of the deck plate cap screws are just a smidge too tight or you have a bit too little lift. I would start by adding some additional worm lift using the lift adjustment may fix it but be aware the lift adjustment usually needs to be very small to maintain optimum worm tooth engagement and these are not fine threaded fasteners. So I would make the smallest possible adjustment to the lift adjuster, observe and if needed continue to adjust. It sounds like your worm is close to optimum so with a small adjustment you should be GTG. If you don't see any change the bottom side cap screws are the next place to adjust. I suggest changing the outer or left side first, test, observe and adjust, if after two cycles you see no change try cracking the inner cap screw a smidge.?

You can verify the cap screws are letting the OPW move by wiggling the end of the counter weight and feeling for movement on the outer end of the OPW where the worm bearing block is attached to the OPW. There should be some movement felt on both axis or chances are you need to crack the outer bottom side cap screw a bit. Keep in mind that a little adjustment goes a long way on all of these coarse threaded fasteners.?
?
Keep us posted.?
--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astropheric Weather Forecast - South Pasadena, CA?
Re: Problem with shift PEC on a Losmandy G11

 

Vincent has been so kind to contact with me to report that unfortunately he was unable to solve the problem and sold the mount, moving to a CEM60. His mount used a Gemini 1, so either the problem is not tied to the Gemini or the part that causes the problem is present in both generations of the computer (code or electronics).

Thus, the problem is still unsolved and in my case means that PEC is unusable in my mount :-(

Best regards,
Daniel,
Re: rehab a G11

 

Losmandy will do that for you, surely, but maybe they are too busy to do it promptly. Basic maintenance is well covered in their videos (cleaning and re-greasing). Worm adjusting is more intimidating though, but may be you don't need that.??

Best of luck,
Daniel
Re: Resetting spring-loaded worm

 

Did you get those spikes in RA too?? ?I'm considering too slightly loosen the far end bottom screw to try to improve my RA performance. Peak values in RA are over 2.5" and those concern me more than the RMS number.

Best regards,
Daniel
Re: Resetting spring-loaded worm

 

That's exactly what Brian says. He only refers to the far end screw that it is beneath the big spring screw though. Unscrew a little and that should free the worm enough to float over the gear.? However, I'm not sure if I'm going to get much benefit of it. Currently DEC is guiding just under 0.4" RMS over 3 hour sessions and it is the RA axis what is limiting the guiding accurary (I get around 0.6" RMS).

Best wishes,
Daniel
Re: rehab a G11

 

Bob

your the perfect person don¡¯t discredit your skills, attention to detail and analytical skills.?


there are plenty of dissemblely guides ?on the net and attention to order of washers. ?Take photos when taking it apart use this site as a guide



Losmandy sell lubricant kits etc. there are many guides on how to adjust your worm and blocks. ?Many have written them but I like Michael Herman¡¯s guides.?


Maybe look to replace the clutch pads they may clean up ok. ?Be careful of some solvents on the anodising surfaces. ? ?Disassemble clean re-assemble?

Might need new worm bearings or such like ruland coupling. ? Check when taking apart so you can order replacements. There are databases of nuts bolts bearings etc you can use in the files section.?

Remember you cannot wreck it. ?


Maybe try run it prior to dissemble and test PE so you have a base line when put back together to see if something is not right.?


You will learn as you go, best way to do it

cheers

bren




--
Brendan
Planetary Nebula - NGC 6781 - HOO

 

Bubbles are my thing right now and this beautiful and popular supernova remnant does not disappoint. Two light years across and 1500 lights years away in the constellation of Aquila, which is sadly somewhat barren of DSO objects.?

?

Total integration time is 3.66 hrs using an 12" F3.9 truss Newtonian, captured with an ASI 294MM Pro camera using Chroma 3nm narrowband filters. No moon was present. Equal number of Ha and Oiii subs.

?

This is a bright object, and I was able to pull out some detail using Pixinsight. Bortle 4/5 sky. Modified Losmandy G11 mount running Onstep.? It's very small for my setup, and I look forward to returning someday with a 3m scope! I was also able to get the little dumbbell (M76) later in the night, so looking forward to seeing how they compare.


?

?

?

Peter
Re: rehab a G11

 

I don't know that good lubricants would deteriorate appreciably in 3 years.? Does the mount work?
rehab a G11

 

hello Bob Hancey, I am a member of the Sac Valley astro soc. we have a G11 mount (older mount) I am in the start of a rehab project for this mount. My greatest concern is that lubricants on the interior of the mount are no longer qualify as lubricants as the scope sat unused for at least 3 yrs. Will attempt to use soon, but do not have a lot of hope movement from the mount. I will contact Losmandy to see if they do rehabs on their mounts and cost to do so. I do not have the skill set to do a breakdown and rehab (I am a retired ICU RN---not much crossover skills for this project). IF my attempt to have Losmandy to do a rehab is a negative, NEXT best hope is to find a person/business that can do rehab (some funds are available), with a location in central/northern Calif and southern Oregon that the mount can be delivered to. SO, if there is anybody within the Losmandy group has a name of person/business that could be of value in terms of getting this mount back into a reasonable/functioning shape for members/visitors can use, any input would be appreciated, respectfully submitted Bob H.
Re: Resetting spring-loaded worm

 


There is nothing else that can cause this in a clean undamaged unmodified G11 or GM8 mount with tucked servos and sprung Gen II OPWs.?

--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astropheric Weather Forecast - South Pasadena, CA?
Re: Bubbly Detail: NGC 7365

 

Sam,

I appreciate your kind comments.? The telescope is Newtonian 12" truss F3.9?Camera is an ASI 294 MM Pro. Image resolution is 0.34"/px. Bin 1 mode.? Personally I think this should be everyone's first scope!? I.e start at 1400mm and work up, while piggybacking a 200mm for wide field. The mount is a g11 modified for high precision guiding under Onstep control.? OAG guiding using guide QHY camera with 2.4 micron pixels.? When I first processed the data set and looked at images on Astrobin I realized I was missing something. That turned out to be Sii data which is all the fine stuff on the outer perimeter.? So I shot for signal.? The data is processed in Pixinsight. Key to revealing detail is deconvolution. The Astro Imaging Channel has a very good tutorial???from three weeks ago for those who want to take it to the next level! You cannot get this level of detail with OSC camera sadly. When you poroces and stack your data consider using Normalized Scale Gradient. It helps a lot when he moon is about. My sky is New Jersey Bortle 5/4 in theory but I think 5 in practice with the LED lighting that is so pervasive now.

Peter
Re: Resetting spring-loaded worm

 

¡±If your back off screw doesn't seem to be working it could be that the bottom cap screws are just a bit too snug to let the OPW move. If they are just a little bit too snug they lock the OPW into position and the worm can't float on the worm gear.¡±

- that is exactly what happened to mine; they were screwed down tight enough that the worm could not float. Slightly loosening them restored the float for the worm gear and resolved the spikes in my guiding.


Geoff Chapman
Re: Bubbly Detail: NGC 7365

 

¿ªÔÆÌåÓý

Agree, Peter- really astonishing! Rivals Hubble images imho. I especially like the dynamic quality of the image, or percussion effect, as you describe.

Can you share any other technical information such as about the telescope and its whereabouts? Do you think the exquisite details are largely due to the narrow band filters and large data set? What is your focusing workflow? I have the OSC version of that camera and don¡¯t think I¡¯ve ever seen such sharp image details, even through the high quality glass of a Stellarvue 102 refractor.?

Thanks again!

Sam

On Aug 21, 2022, at 9:50 PM, HenkSB <haling@...> wrote:

Peter that's a spectcular image, thanks for sharing!? 30 hours integration, a lot of work but it really paid off.? No better way to conclude a discussion than obtaining results like these.? Well done.

Re: Usability Question--Update #2

 

Mark glad to hear things improved

>>> And declared victory for the modeling.

haha yes, i love that sentiment ;)

On Mon, Aug 22, 2022 at 10:47 PM Mark de Regt <deregt@...> wrote:

We had a clear night tonight, with no wind or moon.? So out I went again.

?

After polar aligning with Polemaster (probably not necessary, since the tripod hadn¡¯t moved, but good practice), I turned off the hand controller, put it in CWD position, then did a cold start.?

?

I told it to go to Altair (east side); it wasn¡¯t on the finder scope, but it wasn¡¯t too bad.? I centered, and clicked Menu>Align>Alignment.? I then told it to go to Deneb.? It wasn¡¯t far off center on the illuminated reticle eyepiece; I centered, and clicked Menu>Align>Alignment.? I told it to go to Vega, and repeated the process (it was very close to center).? Finally, I did Alberio (I like Alberio, so I¡¯ll use any excuse to look at it).? It also was close to centered.

?

Going to the west side, I told it to go to Mizar.? It was not very close (not on the finder, but it was on the Telrad).? I centered, clicked Menu>Align>Alignment.? And declared victory for the modeling.

?

I substituted a 26mm Nagler Type 5 as my eyepiece, and told it to go to M27 (east side).? It was pretty well centered.? Repeated for a number of east side targets, all with good success.? Told it to go to M81 (west side); it wasn¡¯t so well centered, but it was on the eyepiece.? Told it to go to M31 (east side); it was at the very edge of the field of the 26mm Nagler.? Told it to go to M57, and it was reasonably well centered.

?

I think that this probably is as good as it gets.? I¡¯ve heard all the people saying that I¡¯m too optimistic expecting everything to be centered, so I¡¯ll accept the imperfections.? It¡¯s good enough for my limited needs.

?

I thank everyone for their help, particularly Brian Valente.

?

I wish everyone clear skies, and a good night.

?

Mark de REgt

?

From: [email protected] <[email protected]> On Behalf Of Mark de Regt via
Sent: Wednesday, August 17, 2022 8:58 AM
To: [email protected]
Subject: [Losmandy_users_io] Usability Question--Update

?

I went through all of the suggestions made, and collected those that seemed might possibly be connected to my problem.? Then I implemented them.

?

Last night was a test.

?

I carefully determined the CWD position.? Although, to be honest, there is absolutely no way I know of to know when the counterweight bar really is pointing as down as it can, since a bubble level depends on catching exactly the right part of the curve, and not moving it at all.? But I also understand that that matters only for the first slew.

?

I slowed the speed at which the mount slews, to lessen the probability that anything skips with the sudden torque.

?

I did a careful polar alignment with PoleMaster.

?

I made sure that time, date, and place were all very accurate.

?

I deleted any existing model.

?

I sent the mount to Altair.? It missed by a fair amount.? I decided that maybe I should only ¡°center¡± using ¡°center¡± or ¡°guide,¡± not ¡°move¡± or ¡°slew,¡± so it took a while to center Altair.? After carefully centering Altair on my illuminated-crosshair eyepiece, I selected ¡°Menu,¡± then ¡°Align,¡± then ¡°synchronize.¡±

?

I told it to go to Vega.? It was almost perfectly centered.? I centered, synced, then told it to go to Deneb.

?

It was perfectly centered.

?

The west side of my sky is pretty much destroyed with Seattle sky glow and trees.? So I decided to play on the east side, to see how it worked,?

It worked very well!? Everything I told it to go to was reasonably well centered.

?

Then I told it to go to Mizar, very much on the west side, but easy to see.

?

It missed by a lot.? I centered it, and synced.

?

I told it to go back to Deneb.? It was on the eyepiece (17mm Nagler Type 4, on a Celestron 11¡± EdgeHD), but quite far off center.? I centered and synced.? Told it to go to M27.? It was centered pretty well,? I told it to go back to Mizar, and it barely was on the eyepiece.

?

And so the night went.? I found no way to get it to converge on a model that got everything reasonably close to the center of the eyepiece (I wouldn¡¯t care so much, except that it¡¯s a royal PITA to center anything, to me, on a GEM, since I have no idea which of the four buttons to hit at any time to get it to move in any particular direction).

?

It was somewhat promising, in that it always got the target on the (very, very wide) eyepiece, but it is far, far from perfect.

?

Mark



--
Brian?



Brian Valente
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