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On Sun, Aug 28, 2022 at 10:34 AM, Brian Valente wrote:

Back to the OP topic, the point here is that spring loaded worms are springy

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Any adjustments that are considered should be made based on performance, not on how things 'ought to feel'

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We just went through this with a reseller (unauthorized) who felt it was a value-add to adjust the worms according to what they thought it ought to feel like, and the result was a mess. We managed to get it resolved by following the factory spring-loaded worm adjustment video.

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On Sun, Aug 28, 2022 at 9:25 AM HenkSB <haling@...> wrote:

On Sun, Aug 28, 2022 at 11:24 AM, Chip Louie wrote:

Henk,

I have never seen or read anything about APs design. When I originally penciled out using a spring loaded OPW on my G11 I did what seemed logical in my mind and used an outward travel limiter only and used as low a spring rate as possible to keep the worm fully engaged in the worm wheel. My thought was that sliding friction was bad and stiction was worse. By reducing sliding friction stiction should not be an issue while guiding. Because the worm should never stop moving once tracking and guiding is started. Additionally having an out travel limiter would help protect the worms.?

My conclusion is based on Roland's explanation in the document that Brian linked.? If you read paragraph 6, I don't know what else to conclude.? It's pretty much what you stated.

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Brian?

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Brian Valente

astro portfolio?

portfolio

astrobin?

Exactly! This is what I keep telling people, if the images work at the pixel pitch you are working at and whatever the atmosphere allows you to achieve who cares what your measurements are??

There are countless film and digital images that are technically flawed that have inspired millions. I have seen technically perfect images that are artless and flat. All images require interesting content otherwise why bother???

Worrying about counterweight shaft wiggle as a backlash indicator for fixed worms used to be somewhat useful though for the knowledgeable still not all that important.? But this is not important or useful in the age of spring loaded worms.?

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Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astropheric Weather Forecast - South Pasadena, CA?

I will be interested to hear the answer, because I feel strongly that equipment should be designed so that plugging something into the wrong socket should not cause damage.? (An engineering best practice that seems to be unknown to astronomy equipment manufacturers.)? I have tape over all the sockets I don't use on my Gemini.

What's intriguing is that it partly works.? There may not be much wrong.

Last night, at a star party, I set up my G11T and plugged my hand controller into the wrong port. It didn’t work of course, but when I noticed it and plugged it into the HC port it would stall out within the first?
few pages at startup. It stalled on the quick start/cold start etc. page or the mount selection page and would not go farther. I have been using my CGX-L mount recently and it isn’t picky at all about where I plug in the hand controller. It isn’t a great excuse but it’s all I’ve got. I tried unplugging everything and waiting for a minute or two a bunch of time, but?had no joy. Does anyone know of a fix short of getting a whole new Gemini 2 setup??

Jeff

Jamie I recently installed the stable release of astroberry.? The Ekos version is 3.5.5.? I am pretty sure that your code is probably not in there.? Is it safe to install the latest version of astroberry?? If they advertise a stable release, then I presume the latest is unstable.

Any advice on how to update/upgrade Ekos in a safe way?? I need something in a later release and started with apt-get update/upgrade and got several error messages.? I am getting errors about Buster and astroberry.? The indillib link talks about an rpi-update command, also telling that it broke the entire installation.

Hopefully nothing is broken after what I did.? Looking at a link in indilib?, it has a long procedure but it's unclear if that is just for upgrading.

Your comment about just upgrading sounds easy, did I miss something?? Of course, I don't want to reinstall my entire distro from scratch, just want the updates, and not from source code.

The asiair is a raspberry pi. If you're comfortable doing so, you can load any rpi distro including astroberry, stellarmate etc. It's a bit of a time and effort investment though. Just use a separate sd card to try it out. Those two distros do have my driver updates.?

If your time settings are off, slews and plate solves can fail. I'd check that first.?
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jamie.amendolagine@...

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On Sun, Aug 28, 2022 at 11:24 AM, Chip Louie wrote:

Henk,

I have never seen or read anything about APs design. When I originally penciled out using a spring loaded OPW on my G11 I did what seemed logical in my mind and used an outward travel limiter only and used as low a spring rate as possible to keep the worm fully engaged in the worm wheel. My thought was that sliding friction was bad and stiction was worse. By reducing sliding friction stiction should not be an issue while guiding. Because the worm should never stop moving once tracking and guiding is started. Additionally having an out travel limiter would help protect the worms.?

My conclusion is based on Roland's explanation in the document that Brian linked.? If you read paragraph 6, I don't know what else to conclude.? It's pretty much what you stated.

I have no insight into the asiair. I don't have one, and haven't been able to gleen what version they are using. I'm not sure what logs they provide, but there may be some version information in those. If you can get those I might be able to tell.?

edit: this is the release log from asiair -- I don't see any mention of indi updates, but I'm assuming that there have been indi updates, and they just don't mention "indi"



Having said that, I don't expect my changes to result in this. I did not modify slew commands.?

Jamie
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jamie.amendolagine@...

On Sat, Aug 27, 2022 at 05:43 PM, Jim Magill wrote:

But how about tolerance to wind?? ?I have been trying to use my 127mm refractor at f7.5 or f5.3 (with the reducer) and having difficulty even with a mild breeze.? ?

With lighter winds, I'd check the inertia being placed about the DEC axis and minimize that.? A 5-inch refractor can increase the inertia significantly about the declination axis.? Dampening a large radius balance wheel (pendulum) structure that can apply torque forces down to the tripod can easily become an issue.? The DEC may not track much, but it can wind up if buffeted.

On 2022-08-27 23:38, Peter Boreland via groups.io wrote:

Chip, if your Ra guide error is twice your Dec error will you get round stars?

If both are smaller than the limit of resolution in the picture, yes.? It is normal for RA error to be larger, because the earth is rotating in RA and not in declination, so we have a motor running in RA but not in declination.

Also, now that we polar-align with very precise methods, we can get dec error extremely small, while RA error is not a lot smaller than it was with older methods.

Henk,

I have never seen or read anything about APs design. When I originally penciled out using a spring loaded OPW on my G11 I did what seemed logical in my mind and used an outward travel limiter only and used as low a spring rate as possible to keep the worm fully engaged in the worm wheel. My thought was that sliding friction was bad and stiction was worse. By reducing sliding friction stiction should not be an issue while guiding. Because the worm should never stop moving once tracking and guiding is started. Additionally having an out travel limiter would help protect the worms.?

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Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astropheric Weather Forecast - South Pasadena, CA?

Peter,

If you look close enough no, but if you backup enough yes. In absolute terms no you should see eggs.

I'm no expert like you guys but like all digital images I imagine it depends on pixel scale, amount of error difference and what scale the resulting images are observed at.?

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Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astropheric Weather Forecast - South Pasadena, CA?

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On Fri, Aug 26, 2022 at 09:06 PM, Brian Valente wrote:

Michael has it correct, you are likely seeing the effects of the spring-loaded worm. It's not a good idea to try to zero it out, that's not how the spring-loaded worms work

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Roland Christen from AP did a nice writeup on this recently (AP mounts have spring-loaded worms as well) which may make for good background reading on this topic:

"why is a mount springy"

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It looks like the AP SLW works different than the Losmandy one.? They have a backoff screw to limit the outward movement of the worm whereas the Losmandy SLW has a backoff screw to limit the inward movement of the worm.? The idea with AP is that the spring pressure is kept low, appropriate for tracking but not? for slewing whereas with Losmandy it is higher to handle the pressure required for slewing and is mostly aimed at preventing bind-up while allowing tighter settings to minimize backlash.? Is that a correct assessment?

Daniel,

Thanks for posting. Captured over 2.5 hrs, great job!

You might want to consider toning down your dither. 10 arcsec dither seems mighty excessive! There are those here who can make a more insightfully recommendation based on your camera pixel size and focal length. You really ought to aim for a few pixels not the other side of the universe.?

On the positive side, recovery after dither is excellent. A+?

Your PE is 8.3" p-p, which is in the range for an unmodded mount. But you do have a 4" p-p second order harmonic. You mind what to try using adaptive PEC in PHD2, and set the period length to 239.34s, and let PHD2 guide out the 120s and 60s errors. If you use PEC then you will need at least two worm period in order to get the 240 and 120 errors. I would not both with the third order harmonic at 60s.

Now the your 76s error is 2.3" p-p. After correction is remains high at 1" p-p. It's twice the size of you 120 and 240s errors after correction This really limits the Ra performance of you mount greatly. We have ways to eliminate this error in the hackers forum.?

What does all this mean. Well your Ra rms error is twice you Dec error. For round stars you want them to be the same order of magnitude. If you got your Ra down to where the Dec axis is, your total rms error would drop from 0.7" to 0.5", which is very good, and seeing on any given night becomes the dominant factor and not your mount.

Peter?

Chip, if your Ra guide error is twice your Dec error will you get round stars?

Peter

Jim, if the wind is noticeably moving your spring loaded worm you might want to batten down the hatches?? you mitigate the wind effect somewhat with a blind of some sort. Most of the time wind gusts cause sudden jumps in dec and Ra that results in crap guiding. If you focal length is under 200 mm you might be OK.

That sounds?exactly like?what I’m seeing! ?I’ll have to try the ethernet connection … thanks for pointer!

The PEC options didn't appear for me when I was connected via USB, but did when I connected using Ethernet; see this thread?in the Gemini-II group.

Ok. I’ll?ignore for now.?