Just a thought…

The ‘Drawing Needed’ thread implies that the pier adapter is attached using a single bolt through the center 0.50” thru hole.
You might instead want to use 3 bolts through 3 of the various sets of (smaller) thru holes (3 points determine a plane…) which should provide better stability.

KW

Hi Ray,

That makes perfect sense. Just a suggestion: maybe you can implement in PEMPro a monitor that would detect a star that is exactly the same brightness for minutes at a time, over multiple exposures. You could then warn the user to adjust the settings, exposure time, check for a hot pixel, etc. During testing of PEC + L6, I saw a number of logs that contained that same saturated pixel level, so it's not that unusual.

Regards,

?-Paul

On Fri, May 3, 2024 at 06:14 AM, Ray Gralak wrote:

ecause in your log the star brightness values are all exactly 32767.00. When a star is saturated it can produce a large flat region of the same brightness which can result in an inaccurate star centroid calculation, thus the jagged graph.

?

You mean to tell me this program has trouble chasing the centroid of an artificially bloated star that is already scintillating due to poor and variable seeing conditions and a mount with periodic error that also moves it? That doesn't seem likely at all.?

Jokes aside, this makes sense. From what I've seen, the mount has periodic error visible in the graphs and follows this pattern (somewhat M-shaped) for a number of cycles and then it goes what seems to be chaotic for a cycle or several and then back to "normal." I'm wondering if the smooth parts of the graph are during steadier seeing, when PEMPro might have more a shot at getting the centroid of an otherwise bloated star correct. There didn't seem to be any rhyme or reason for the jaggedness (exact part of the sky I was collecting data, length of time I had been collecting data, tightness of the gear mesh, temperature). My cables appear like new; my batteries are new or newer; I've used a variety of quality power cables; grease looks good; the worm and coupler appeared to be moving normally, at least visually, and things appear to be in a straight line when slewing; when not in use, the mount is stored in relative humidity levels of between 20-30% inside of a mattress bag on a pier with desiccant).?

I'm a little nervous to get my hopes up, but "user error stemming from thinking he is so smart he didn't need all of the detailed and easily-understood instructions provided with the software and available online," has been an accurate description of some of my behavior in the past. You were too polite to say that exactly, but I know myself. I'll report back.?

George

The second video suggests that the wobble is coming either from the adapter base to flat pier plate connection, or the flat plate to pier connection.

I think I’d take a close look at those connections around the flat plate. Maybe the plate isn’t flat, or something is giving the false impression that a bolt is tight when it’s not fully tight.
If you don’t have washers between the pier adapter and the flat plate, try inserting one at each bolt.
Good luck.

开云体育

That is somewhat heartening, oddly. The reasons I bought a mount I can work on (very inexpertly) and whose electronics can easily be separated from the rest of the mount might be? playing out. I am using L5, PIC v1. I will replace the gearbox this weekend, though this will coincide with a week of cloudy weather. I have the mount in an observatory so I can jump at the first clear skies I get.

When the mount has worked well, it has really worked well. This jaggedness has always been there since I first bought PEMPro (winter) in an attempt to improve tracking for DSO imaging, but it has had moments of brilliance compared to every other mount that I've owned. Will update as soon I change out the gearbox and get some clear weather. Thank you so much for the information, observation, and suggestions.?

George

Hi George,

Attached are some pics of the gearbox internals and their respective periods (courtesy Mr. Fujita). None of the gears appear to have a rotational period aa fast as the errors you are mentioning, as Paul said. Just as a test, you may want to try some slews with the motors unmounted and observe the motion of the brass pinion gear. It should be rotating smoothly with no wobble or off-center motion. If there is wobble, you could have a bent motor shaft or bad pinion gear itself.

Other than some software leads the Paul has an idea on, the only thing I could think of would be some type of electrical short or bad contact. Check your motor cables for kinks or pinches. You could also check each of the individual leads for continuity with a multimeter, and make sure each contact is isolated from the other pins.?

Fast oscillations are not reported here much as I can recall. Good luck!

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, Sequence Generator Pro and PixInsight user

George, I've never seen this behavior before. If you try swapping the gearboxes and still get the same result (and also try swapping servo cables, if you can), I'd start suspecting Gemini controller itself, possibly the PIC Servo firmware.?

Remind me, are you using L6 and PIC firmware v3, or still on L5, PIC v1?

Regards,

? ? -Paul

On Thu, May 2, 2024 at 04:44 PM, Russ wrote:

a better video

Russ,

From my view it shows pressing against the top of the pier, below the mount.? When that pier flexes (slightly distorts) this adds energy into the mount above using its inherent inertia to oscillate on the flexing pier.

The only thing I can think of is to disassemble the whole ALT/AZ portion of the mount and look for loose screws. There are several Allen head bolts that hold the slotted ALT risers up from the bottom I believe, though I'm not finding my pics of the last teardown. That part of the base should all be tight; if you can get a feeler gauge in any of the joints that should not happen. As the weight shifts back and forth over many sessions, any screw in that area might work loose.

Good luck!

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, Sequence Generator Pro and PixInsight user

No but I should have. Tested after putting scope back on but I did verify a few times every single bolt throughout the system was very tight.

Agree. I removed everything down to the pier. Tried to rock the pier but it was solid with no movement. I then attached the G11G base adapter to pier, then the RA extension, then the G11G and finally the SW120ed scope. All bolts were tightened yet the amount of wobble in the entire assembly is very noticeable even with just a slight force anywhere on the mount. Video does not show the movement very well but I can use a single finger and rock everything with very little force.

Its really hard to tell from the video.

Remove the scope and take the G11G off the pier.? Go through and tighten all cap screws.? You should also remove the bottom mounting plate and check the 4 cap screws for the two mounting brackets for the Alt assembly.? Also check the worm to ring-gear spacing for both the RA and DEC.? Check the pier mounting bolts.

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Jim W
Phoenix, AZ. USA

Losmandy G11G w/ L6, NINA 3.0 / ASTAP, ASI2600MC Pro, Sky-Watcher Scopes, Canon L Lenses.

Apologizes, not sure the video is really helping you see the movement (I am applying very little pressure) but the whole mount is actually wobbling.

Sounds like we have the same setup. I have never touched the 2 bolts above the RA adjustment (below). I did check these just now and they appear tight. With regards to the ALT 4 adjust bolts, I usually just had the hand tight but last night after PA, I tightened all 4 extremely tight to see if I can reduce the mount wobble. Not sure if it helped any though because mount still seems to wobble (top heavy?). I took a 5 sec video and was thinking of creating a new thread to see what others think (If my 5 sec video can be uploaded here).

I like you idea of using additional washers and I am going to see about purchasing those.? Really appreciate your help!!

Thanks, Jonathan. The mount is from 2020 but had been stored in its original box and never used until I bought it in 2023 (the original owner never used it). The grease looked good when I checked it recently.?