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Equipment Discussions >> Mounts

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nganga
super member


Reged: 03/16/08

CGEM motor cogging
      #5537628 - 11/24/12 06:17 PM

Hello,

A firmware fix was supposedly in the works to fix this problem. Does anyone know the status of this?

Clem


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Stew57
Carpal Tunnel
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Reged: 05/03/09

Loc: Silsbee Texas
Re: CGEM motor cogging new [Re: nganga]
      #5537705 - 11/24/12 07:09 PM

Supposed to be ready early next year.

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nganga
super member


Reged: 03/16/08

Re: CGEM motor cogging new [Re: Stew57]
      #5537919 - 11/24/12 10:04 PM

Quote:

Supposed to be ready early next year.




Thanks Mark.

Clem


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svtdoug
sage


Reged: 02/07/11

Loc: Gig Harbor, WA, USA
Re: CGEM motor cogging new [Re: nganga]
      #5554760 - 12/04/12 10:21 PM

Supposedly very soon. Most issues have been solved, waiting for beta release to test.

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orlyandico
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Reged: 08/10/09

Loc: Singapore
Re: CGEM motor cogging new [Re: svtdoug]
      #5554931 - 12/05/12 12:41 AM

I've finally seen this cogging for myself.

I suspect the fix will entail keeping the motor powered even when its not moving so it doesn't slip back to one of the cog positions.


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svtdoug
sage


Reged: 02/07/11

Loc: Gig Harbor, WA, USA
Re: CGEM motor cogging new [Re: orlyandico]
      #5743888 - 03/19/13 08:01 PM

I, along with other beta testers, have been working with Derek of Celestron, on
a firmware fix for this Dec Cogging issue for over a year now. Derek has been
most helpful, but he has not been allowed to finish the fix. He has been pulled
off the project for months at a time, to work on new products, etc. Last month
we were told that Derek was back on the project and it was his highest priority,
and that we should have something to test this month (March of 2013). This week
we found out he has been taken off this project once again, and that it will be
"next" inline. We have heard this so many times before.

I just wrote Celestron telling them of my frustration - that I am unable to use
my mount for any serious imaging until this fix is accomplished, and with star
party season fast approaching, my satisfaction with the CGEM is quickly eroding.

If you have a CGEM or CGEM DX mount with the saw tooth dec cogging issue, and
are frustrated with the delay in getting a fix, it may be helpful for you to
email Celestron Tech Support, and let them know that you are interested in getting this issue solved quickly. You can write to them at -
http://www.celestron.com/c3/support3/index.php?_m=tickets&_a=submit

I am sure this issue is affecting their sales, and their reputation. Hopefully
some pressure upstream in management will help them to rethink their priorities.

Doug


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svtdoug
sage


Reged: 02/07/11

Loc: Gig Harbor, WA, USA
Re: CGEM motor cogging new [Re: svtdoug]
      #5743994 - 03/19/13 08:59 PM

Update: I just had some feedback and encouragement - that the more folks who let Celestron know about this issue - and the delay in getting it fixed, and how it is affecting them and their use of the CGEM, the more likely it is to get fixed soon.

Thanks,

Doug


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orlyandico
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Reged: 08/10/09

Loc: Singapore
Re: CGEM motor cogging new [Re: svtdoug]
      #5744146 - 03/19/13 10:27 PM

IMNSHO.. Celestron probably cares less about us CGEM owners because they already got their money from us. And I understand the AVX doesn't have this problem, so going forward, if ever they come out with a CGEM AVX, the pressure to fix this DEC cogging will vanish. After all, we are not new sales.

Given that a very good polar alignment would allow minimal to no DEC guiding at typical focal lengths, maybe the DEC cogging is not as severe an issue as we all think? for me the 8/3 is a more severe issue..


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svtdoug
sage


Reged: 02/07/11

Loc: Gig Harbor, WA, USA
Re: CGEM motor cogging new [Re: orlyandico]
      #5744423 - 03/20/13 03:16 AM

Orlyandico,

Celeston HAS committed to fixing this issue, as evidenced by the amount of work and several firmware beta versions already produced. That has been established. They just have not committed the resources to finish the job.

A good polar alignment is great for those fortunate to have a permanent mount, but for those like me who do not, a near perfect polar alignment is energy and time consuming. And for what ever reason, I find that it works for a while, but eventually the drift rate increases, requiring more fussing with the polar alignment.

I own a 2 axis auto guider and a mount that was designed and advertised to guide in two axis for one reason - that is to use it for guiding in two axis. Anything short of that, in my opinion, is not getting what you paid for.

FWIW, I do not have any probables with the 8/3 issue.

Doug


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dickbill
scholastic sledgehammer


Reged: 09/30/08

Re: CGEM motor cogging new [Re: orlyandico]
      #5744855 - 03/20/13 10:50 AM

Quote:

I've finally seen this cogging for myself.

I suspect the fix will entail keeping the motor powered even when its not moving so it doesn't slip back to one of the cog positions.




what does it look like, oscillations in dec?


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orlyandico
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Reged: 08/10/09

Loc: Singapore
Re: CGEM motor cogging new [Re: dickbill]
      #5745055 - 03/20/13 12:30 PM

Sawtooth pattern.

Generally with DEC guiding, there is a lot of backlash, a dead spot if you will. So by deliberately mis-aligning the azimuth a little bit, you can ensure that all DEC corrections are in one direction only. So once the slack has been taken up, DEC corrections should be "instantaneous."

The problem with the CGEM is that the motor has 5 lobes on its armature, and it "cogs" i.e. if you command the motor to move a very small amount, it will not move that amount unless the amount is at least one rotor lobe. This is because the rotor lobes are attracted to the magnet.

You can feel this cogging effect on stepper motors - if you turn them by hand, you can feel the "grittiness." But - a stepper motor has 200 lobes on its armature.

So what happens with the CGEM is, as your DEC drifts off, the guider commands a correction. But until that correction is big enough (i.e. long enough, i.e. the DEC drift is big enough) for the motor to rotate by one cog, the motor won't rotate. Or it might, but it "snaps" back to the previous position.

The net effect is your DEC error has to grow to a certain level before the DEC axis moves back. It is exactly the same effect as stiction. On my mount (AP600) the axis won't move until a substantial-enough torque is applied. This is mechanical and is an axis problem, rather than a motor problem. But the effect is the same, the DEC error has to build up to enough of a level before it gets corrected.

I spent a Mach1 to banish the DEC stiction on my AP600. But after doing a very good polar align of the AP600 (2' from the pole) I discovered that I can get away with not guiding in DEC at all, for up to 10 minutes. So this is one possible solution to cogging or stiction.

This solution isn't good enough for 20 minutes, and I don't think it would work for a CGEM. The AP600 has very stiff axes (which contributes to the stiction) but the effect is, whatever small DEC backlash it has, it doesn't move very often due to wind etc.

My CGEM has real bearings in DEC, so this means the slightest wind or cable drag will cause it to bump up against its limits (since the worm and ring gear can't be 100% tight against each other). When that happens, you need to correct in DEC right away.

Some people have used a string to deal with the cogging. I'm not entirely sure about the details of that.


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svtdoug
sage


Reged: 02/07/11

Loc: Gig Harbor, WA, USA
Re: CGEM motor cogging new [Re: dickbill]
      #5745180 - 03/20/13 01:45 PM

Quote:


what does it look like, oscillations in dec?




There are at least two ways to determine if you have this issue with your mount.

1st way: If you have a phd guiding graph that looks like this - a very
pronounced saw tooth pattern:
http://edhiker.blogspot.com/2011_10_01_archive.html#2779568578551726255

2nd Way: Using the hand controller, select "GET RA & DEC" from the main menu or
"GET AXIS POSITION" under the "UTILITIES" menu. Set the slew rate to 1 or 2
(0.5X or 1X sidereal rate, the kind of rate you would use in guiding) and press
the north or south button for about half a second. Normally, the DEC position
will change by a few arcseconds. But if you continue short steps in the same
direction, you may find a point at which the displayed dec position will no
longer advance. The numbers might change a bit in response to pressing the
button, but then come back to about the same value. The same thing happens when
you are trying to guide. The result is that if you limit the pulse to half a
second (500 milliseconds) and keep going in the same direction it will never get
past this "bad spot", until the size of the correct gets large enough to
overcome this "bad spot" or cog of the motor. I looked at the drive signals to
the DEC motor and saw that each time I pressed the button the motor would be
driven, but then the voltage would go to zero, even though the position slipped
back. This is not how a traditional servo system works...
Pasted from <http://www.cloudynights.com/item.php?item_id=2702>

Here is a video I made of checking the dec using this method -
http://www.youtube.com/watch?v=bVqW8ZGi7_4 Note, this video was made with the
dec motor removed, but the same check can be made without taking the mount
apart.

The result of this problem with imaging is that you will end up with inaccurate
guiding, resulting in oblong stars and blurred images.

Doug


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dickbill
scholastic sledgehammer


Reged: 09/30/08

Re: CGEM motor cogging new [Re: svtdoug]
      #5745248 - 03/20/13 02:18 PM

Thanks Orlyandico and good video Doug, with a very clear reccord of the 'spring back'.
Your video suggests the easiest (the only?) solution might be to change the slew rate to 3 or 4, to break the cogg, but the guiding software might not give this option.
I think phD guides at a slew rate of 1 or 2, is it imposed by the mount?


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orlyandico
Post Laureate
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Reged: 08/10/09

Loc: Singapore
Re: CGEM motor cogging new [Re: dickbill]
      #5746106 - 03/20/13 08:06 PM

If you increase the speed of the guide rate, PHD calibration will notice this increased speed. So PHD will use shorter pulses ( speed X time = distance )

So the cogging will still be there.

Only option is wait for a firmware fix, or don't buy a CGEM or CGEM DX.

Or don't guide in DEC.


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dickbill
scholastic sledgehammer


Reged: 09/30/08

Re: CGEM motor cogging new [Re: orlyandico]
      #5747201 - 03/21/13 09:36 AM

but then, it could be a fix in the guiding software (phd...) as much as in the celestron firmware.
For example, an option to change the rates or guide pulses in dec only.

I use phd with short pulses (400ms), which is well enough to move the star 24 pixels during the North Dec calibration, in ~10-20 steps, but barely enough to move the star back south a few pixels.
Is this due to backlash, cogging or both?


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svtdoug
sage


Reged: 02/07/11

Loc: Gig Harbor, WA, USA
Re: CGEM motor cogging new [Re: dickbill]
      #5747751 - 03/21/13 02:39 PM

Quote:

but then, it could be a fix in the guiding software (phd...) as much as in the celestron firmware.
For example, an option to change the rates or guide pulses in dec only.

I use phd with short pulses (400ms), which is well enough to move the star 24 pixels during the North Dec calibration, in ~10-20 steps, but barely enough to move the star back south a few pixels.
Is this due to backlash, cogging or both?




That is due to backlash. I looked into this once with PHD, by communicating with the developer. When PHD does the calibration routine in dec, I wondered if that information about backlash (the amount of guiding pulses needed to reverse the direction in Dec) is used during guiding to reverse the dec guiding pulses, if there were an occasion to reverse corrections due to wind or whatever. The answer is no, PHD does not take that into consideration. Therefore, at least with my mount, if there is a need to reverse the direction of dec guiding, there is a LONG wait to get that reversal done, and a large deviation in the dec guiding graph. But my backlash is larger than what is suggested by the post above.

Doug


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orlyandico
Post Laureate
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Reged: 08/10/09

Loc: Singapore
Re: CGEM motor cogging new [Re: svtdoug]
      #5747983 - 03/21/13 04:25 PM

MaximDL can overcome the backlash when guiding in DEC. You can define how long a pulse to send when reversing direction. For example if it takes 10 seconds worth of DEC guiding pulses to take up the backlash, you can define this so if a reversal is needed Maxim will immediately send a 10 second long pulse.

The problem then is.. will a 10-second long pulse result in elongated stars. If you're doing narrowband, then no. But if unfiltered, you would almost certainly get elongated stars.

There is really no way to totally solve declination guiding issues except to buy a high-end mount.


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dickbill
scholastic sledgehammer


Reged: 09/30/08

Re: CGEM motor cogging new [Re: svtdoug]
      #5748222 - 03/21/13 06:18 PM

Quote:

I wondered if that information about backlash (the amount of guiding pulses needed to reverse the direction in Dec) is used during guiding to reverse the dec guiding pulses, if there were an occasion to reverse corrections due to wind or whatever. The answer is no, PHD does not take that into consideration. Doug




Have you tried with high backlash setting in the hand controler and/or with PEC on?

I tried two times to guide with PEC ON, and found it might be better (slightly). I got to try again...


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andysea
Pooh-Bah
*****

Reged: 09/03/10

Loc: Seattle, WA
Re: CGEM motor cogging new [Re: dickbill]
      #5749448 - 03/22/13 10:54 AM

You guys have far more patience than I have for sub standard equipment!! Typically I just get rid of it and swear off that manufacturer.
I'm impressed with your perseverance!!


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Patrick
Postmaster
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Reged: 05/16/03

Loc: Franklin, Ohio
Re: CGEM motor cogging new [Re: andysea]
      #5749577 - 03/22/13 12:25 PM

Quote:

You guys have far more patience than I have for sub standard equipment!! Typically I just get rid of it and swear off that manufacturer.
I'm impressed with your perseverance!!




Not everyone can afford to swear off the cost leaders...

Patrick


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dickbill
scholastic sledgehammer


Reged: 09/30/08

Re: CGEM motor cogging new [Re: Patrick]
      #5749616 - 03/22/13 12:47 PM

well, we are being finicky here. These issues are probably of no consequences at focal lenght under 1500 mm. It's only when you go over that that you need to consider all the smallest issues.

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orlyandico
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Reged: 08/10/09

Loc: Singapore
Re: CGEM motor cogging new [Re: dickbill]
      #5749961 - 03/22/13 03:27 PM

not really.. the 8/3 on mine is so huge that even 500mm unguided is problematic..

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Mike X.
scholastic sledgehammer


Reged: 06/28/10

Loc: Greece-Athens and Rome-Italy
Re: CGEM motor cogging new [Re: orlyandico]
      #5750026 - 03/22/13 03:58 PM

I'm getting more and more convinced towards an atlas or the new azeq6pro...I would love to have a Cgem but...not the 8/3 error...

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rmollise
Postmaster
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Reged: 07/06/07

Re: CGEM motor cogging new [Re: Mike X.]
      #5750207 - 03/22/13 05:16 PM

Don't forget the original Atlas. Cheap. Robust. Known quantity...hard to go wrong with it.

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Geo.
Carpal Tunnel
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Reged: 10/01/08

Loc: Upstate NY
Re: CGEM motor cogging new [Re: Mike X.]
      #5750246 - 03/22/13 05:31 PM

Quote:

I'm getting more and more convinced towards an atlas or the new azeq6pro...I would love to have a Cgem but...not the 8/3 error...



Of course these use stepper motors, which can have their own issues, but advanced drivers can keep a stepper energized to hold it between steps. This sounds like what Celestron is trying to get to, I guess.

The Nexstar SE6/8 mounts use an Indian made motor. The 5/8 and 5/8i mounts used Pittman Lo-Cog drives. I think were found in the CGE and the Meade LX200GPS 16" mounts. Too bad these aren't a swap out, I have a box of them. The Lo-Cogs have "twisted" amature cores so no one spot is attracted to one field magnet.


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Mike X.
scholastic sledgehammer


Reged: 06/28/10

Loc: Greece-Athens and Rome-Italy
Re: CGEM motor cogging new [Re: Geo.]
      #5750334 - 03/22/13 06:17 PM

Very true Rod

Geo..true..steppers have their cons too but so far the SW seems to have a better record.
I am a celestron fan personally... But if the steppers provide me the same tracking resolution with they servo counterparts that's what made me think I favor of them,


Edited by Mike X. (03/22/13 06:29 PM)


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tboconnor
member


Reged: 01/14/10

Re: CGEM motor cogging new [Re: Mike X.]
      #5751122 - 03/23/13 02:11 AM

I just checked mine - when I set the rate to 2, and look at the RA and DEC numbers, I dont see any pauses or movement back when moving the mount.

Does this mean I dont have a cogging issue?


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Raginar
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Reged: 10/19/10

Loc: Rapid CIty, SD
Re: CGEM motor cogging new [Re: tboconnor]
      #5751436 - 03/23/13 09:46 AM

tboconnor,

You won't see it until you're guiding. Your PHD graph will have a 'sawtooth' pattern in declination.

Very frustrating, and the reason most of us get rid of our CGEMs. Mine was 'fixed' via hypertuning (thanks Ed!) but only at lower weights than I wanted (<20# was the sweet spot for my particular mount).

I was up front when I sold it.

Chris


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svtdoug
sage


Reged: 02/07/11

Loc: Gig Harbor, WA, USA
Re: CGEM motor cogging new [Re: tboconnor]
      #5753006 - 03/23/13 11:37 PM

Quote:

I just checked mine - when I set the rate to 2, and look at the RA and DEC numbers, I dont see any pauses or movement back when moving the mount.

Does this mean I dont have a cogging issue?




With the mount balanced in Dec, if you are pressing short (about half a second) blips with the hand control in dec, and the dec numbers continue to go up or down, without any hangups, or rollback, then you likely do not have the issue. Do check both directions though. Check going one way for a minute of short bursts, then reverse and check the other direction for a minute or so. But as Chris suggested, check your PHD guiding graph for any sawtooth pattern in dec to make sure. If you want more information on this check - I posted a video further up this thread.

Cheers,
Doug


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svtdoug
sage


Reged: 02/07/11

Loc: Gig Harbor, WA, USA
Re: CGEM motor cogging new [Re: svtdoug]
      #5787300 - 04/09/13 02:44 AM

Just a quick update on the cogging issue. We received a new beta motor control firmware version from Celestron about a week ago for testing. The early test result are encouraging. The dec cogging seems to be cured, no sign of it from any testers. There are several intermittent issues that we and Celestron are dealing with, but those might be due to other things than the firmware, a sick RA motor in my case. I have done a lot of testing, but all indoors, as we have had non-stop cloud cover since the beta release. Other tester have been able to guide and the results are good, so far.

The bottom line is that Celestron heard from the user community and put the resources where they need to be to get this problem solved. Hopefully there will be a stable version soon for public release.

Thanks for all who commented about this issue.

Doug


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jonbosley
professor emeritus


Reged: 10/19/05

Loc: Texas
Re: CGEM motor cogging new [Re: svtdoug]
      #5787849 - 04/09/13 11:21 AM

That is very good news Doug I am glad Celestron are finally addressing the issue, it has most likely hit sales as they have know about this issue for a long time.

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Raginar
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Reged: 10/19/10

Loc: Rapid CIty, SD
Re: CGEM motor cogging new [Re: jonbosley]
      #5788079 - 04/09/13 01:13 PM

That was always the problem in the past. They had some software ideas to get rid of the cogging, but it always hard broke some other routines.

Hopefully they can figure it out. I really liked my CGEM.


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Mike X.
scholastic sledgehammer


Reged: 06/28/10

Loc: Greece-Athens and Rome-Italy
Re: CGEM motor cogging new [Re: Raginar]
      #5788227 - 04/09/13 02:07 PM

I'm really glad they come out with a fix!!! Thats great news!! (even if i just bought an azeq6gt 2 weeks ago...Couldn't wait anymore )

Edited by Mike X. (04/09/13 02:10 PM)


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dickbill
scholastic sledgehammer


Reged: 09/30/08

Re: CGEM motor cogging new [Re: Mike X.]
      #5788574 - 04/09/13 04:01 PM

That's great news. Assuming that happens and we can download the upgrade from C, does it require a special cable ? i never did that.

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Raginar
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Reged: 10/19/10

Loc: Rapid CIty, SD
Re: CGEM motor cogging new [Re: dickbill]
      #5788598 - 04/09/13 04:15 PM

Dickbill, you'll need a cable like you use to do computer control.

Also, they thought they had this fixed last year too. Don't hold your breath. The guy who does it ends up getting pulled to work other projects; they already have your money


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svtdoug
sage


Reged: 02/07/11

Loc: Gig Harbor, WA, USA
Re: CGEM motor cogging new [Re: Raginar]
      #5813822 - 04/21/13 06:48 PM

I'm pleased to report that beta testing is going well for the CGEM motor control firmware update that addresses the Dec cogging issue. We are testing the second version this month and results are very good - no dec cogging, and dec RMS values of 0.25 pixels during guiding has been achieved.

But, we need more testers. If you have a CGEM, and are somewhat familiar with updating the firmware via MCUpdate, and can do somewhat controlled tests and write concise reports of the results, and would like to participate - here is how:

1. Go to Teamcelestron.com and register as a member.

2. If you don't already have MCUpdate and HCUpdate installed on your computer, go to the Celestron website, download and installed these two programs. These are the required programs to update your mount's firmware.

3. Go back to the TeamCelestron website, click on the Firmware link, then the Motor Controller section, then the Version 31.07 section. Read through this section to get an idea of what is going on. It also would not hurt to read through the previous version 30.91 thread to see what issues have come up and have been resolved.

4. Download the 31.07.cel file. Its in the first post by Derik in the 31.07 section and install it in your Motorcontroller folder (which will be created on your computer when you install MCUpdate.exe).

5. Run MCUpdate.exe. The beta version 31.07 will now be in the list of available firmware updates. Select it and load it into your mount for both axis - Azmith and Alt.

6. Read all the disclaimers about testing beta firmware, understand the risk, and please test every function that you have ever used with your mount. All the utilities and Setup functions. You can do a lot of testing indoors if you have cloudy conditions. Of course, setup, aligning, ASPA, and guiding under the stars is the best test.

The more testing we can accomplish, the quicker this version will be released to the public.

If you have any questions, please ask!

Thanks!

Doug


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gmartin02
professor emeritus
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Reged: 04/11/05

Loc: Santa Clarita, CA
Re: CGEM motor cogging new [Re: Raginar]
      #5813959 - 04/21/13 08:18 PM

Quote:

That was always the problem in the past. They had some software ideas to get rid of the cogging, but it always hard broke some other routines.

Hopefully they can figure it out. I really liked my CGEM.



This is incorrect. The other big introduced problem (that was so hard to track down) in the firmware that addressed the Dec cogging issue was unrelated to the Dec cogging fix. It's a long story, but available by reading the TeamCelestron motor control forum posts.


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amdizack
member


Reged: 08/23/12

Loc: Goodyear, AZ
Re: CGEM motor cogging new [Re: gmartin02]
      #5814006 - 04/21/13 08:41 PM

I have had my CGEM for 6 months, and just noticed this issue last night. I ONLY had the issue when I was imaging East of the Meridian. Anything I started tracking in the West came out just fine.

Does this fit into the category of this CGEM issue? Or would I see it East AND West of the meridian?


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gmartin02
professor emeritus
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Reged: 04/11/05

Loc: Santa Clarita, CA
Re: CGEM motor cogging new [Re: Raginar]
      #5814008 - 04/21/13 08:41 PM

Quote:

Dickbill, you'll need a cable like you use to do computer control.

Also, they thought they had this fixed last year too. Don't hold your breath. The guy who does it ends up getting pulled to work other projects; they already have your money



If you were holding your breath, it might be almost time to exhale.

As Doug said above, we have gotten 2 new beta versions in the last 3 weeks, and the latest version is guiding really well in Dec (for me now better than guiding in RA). We could use some more beta testers.

Note: The new motor control firmware is based on "beta" code (not just a tweak to the existing release code, but a re-write from scratch), and has not been thoroughly "fine tuned" yet for public release. That being said, I am now able to use the current beta MC release for multi hour unattended guided imaging without issues.

"The guy who does it..." actually has a name, which is Derik.

Derik, you rock!

Greg


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gmartin02
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Re: CGEM motor cogging new [Re: amdizack]
      #5814208 - 04/21/13 09:56 PM

Quote:

I have had my CGEM for 6 months, and just noticed this issue last night. I ONLY had the issue when I was imaging East of the Meridian. Anything I started tracking in the West came out just fine.

Does this fit into the category of this CGEM issue? Or would I see it East AND West of the meridian?




My CGEM initially had more problems Dec guiding close to the pole. With more use, as the mount continued to break in, the Dec cogging issue appeared to become worse across all latitudes, regardless of which side of the meridian I was guiding on. I wonder if the object(s) you were guiding on East of the meridian was higher in celestial latitude than the object(s) West of the meridian?


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tboconnor
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Re: CGEM motor cogging new [Re: gmartin02]
      #5816572 - 04/22/13 11:35 PM

This is really great news - I have one of the older hand controllers - will I be able to update it with this firmware?

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wolfman_4_ever
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Re: CGEM motor cogging new [Re: tboconnor]
      #5816629 - 04/23/13 12:14 AM

looks like Derik just released 31.11 beta and it for the cgem's and cge-pro's..

Go join the beta team!


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gmartin02
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Re: CGEM motor cogging new [Re: tboconnor]
      #5817755 - 04/23/13 03:11 PM

Quote:

This is really great news - I have one of the older hand controllers - will I be able to update it with this firmware?



I am pretty sure the answer is "Yes". I think any of the CGEM supplied HCs can be used to upgrade the newest HC or MC firmware. It's best to upgrade to the most recent "official release" HC (4.21) & MC (6.17) versions and make sure those work on your mount before trying a beta MC version.

You can check your firmware versions by using the Version option on the Utility menu in the HC.


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Re: CGEM motor cogging new [Re: gmartin02]
      #5832603 - 04/30/13 03:37 PM

Beta testing going well, now have third version this month. Only remaining small bug is we are getting some bumps in dec guiding when using anti-backlash settings, if the dec changes directions. No reports of any dec cogging from about a dozen testers.

Jointly, Derik from Celestron is testing the same firmware version for CGE Pro mount. If you have a CGE Pro mount, Derik needs beta testers badly. If you can test - please go to TeamCelestron.com, register and follow the thread on Firmware/MotorControl/Version 31.15.

Thanks,
Doug


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Re: CGEM motor cogging new [Re: svtdoug]
      #5832813 - 04/30/13 05:23 PM

Cool, thanks for the update. I haven't started AP with my CGEM, but I have a feeling this will be a must have when I do.

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TimP
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Re: CGEM motor cogging new [Re: svtdoug]
      #5832891 - 04/30/13 05:57 PM

This is great news. Thanks for updating the post.

Tim


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tboconnor
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Re: CGEM motor cogging new [Re: TimP]
      #5832967 - 04/30/13 06:39 PM

I've been using the beta for a few days. I haven't really

Y been able to properly test it for AP, but I like the way the. Motors behave when slewing. Seems a lot more precise for some reason.


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svtdoug
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Re: CGEM motor cogging new [Re: tboconnor]
      #5881172 - 05/23/13 09:39 PM Attachment (38 downloads)

We thought the new motor control firmware would be released by now, but there have been several users with strange results, and Derik is exploring whether they are due to hardware issues or the firmware.

But here is proof that the new firmware solves the dec cogging issue. This image is my first with my C8 at the full 2000mm fl. I never was able to guide well enough to attempt before.

This image consists of 23, 5min frames, with no throw-outs. It was shot 3 days before a full moon, on 4/22/13, so it did have some gradient issues, but I was pretty pleased with the guiding.

M-51
CGEM with 31.17 beta MC firmware
C8 OTA
ST80 and SSAG for guiding
Modified Canon XSi
Captured with Backyard EOS, stacked with DSS, processed with PS-3.

Doug


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Raginar
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Re: CGEM motor cogging new [Re: svtdoug]
      #5881602 - 05/24/13 03:36 AM

Wow Doug, gorgeous

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Stew57
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Re: CGEM motor cogging new [Re: svtdoug]
      #5881843 - 05/24/13 09:36 AM

I wish they would have just fitted the VX motors into the CGEM/DX. Would solve the 8/3 error and the cogging. Seems a waste to spend all this time developing firmware that will have to be replaced if motors and control board are changed. I hope they are still going to do the change. I do hope they have not changed their mind.

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gmartin02
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Re: CGEM motor cogging new [Re: svtdoug]
      #5882255 - 05/24/13 12:59 PM Attachment (25 downloads)

Nice shot Doug (I think I have seen it before on a TeamCelestron post).

Here is more proof that the Dec cogging issue is fixed. The attached picture is of M92

Specifics:

Scope: AT8RC w/AP CCDT67 focal reducer - f/l about 1090mm
Camera: Canon T2i w/Astronomik CLS clip-in filter @ISO 1600
Guiding: Tak FS-60 w/Orion SSAG guide camera
Set of 13 - 4 minute stacked subs combined with set of 13 - 45 seconds stacked subs.

I could never do 4 minute guided subs with the CGEM at this focal length & weight without massive star trailing until using the new beta firmware.


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gmartin02
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Re: CGEM motor cogging new [Re: gmartin02]
      #5882270 - 05/24/13 01:05 PM Attachment (22 downloads)

Here is another image with the new beta firmware on the CGEM.

Same scope/guiding setup as above.

M81, 16 - 400 second subs stacked


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Ron (Lubbock)
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Re: CGEM motor cogging new [Re: gmartin02]
      #5882387 - 05/24/13 01:57 PM

You guys are killing me with your nice images. I can't download the new MC firmware due to a communication issue with the hand controller port. I upgraded the HC firmware successfully to 4.21, and something suddenly stopped working (probably a bad cable or driver issue). Can't connect to the HC at all, even with NexRemote. I'm waiting for replacement cables from AstroGadgets.com to arrive. I hope it's just a bad electrical connector and I can install the new firmware. Until then, I have to get perfect Dec. alignment to avoid the dreaded sawtooth pattern. Oh well, it's a full moon week anyway.

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Re: CGEM motor cogging new [Re: Ron (Lubbock)]
      #5882397 - 05/24/13 02:01 PM

Don't we need to see pictures over 480secs to prove that it's actually gone? Without it, you've just confirmed that it works within a worm gear cycle. I always had success at 5 minutes or so, I never got much beyond that.

Can you guys remove your reducers too? It'd be nice to see long focal length shots. 1000mm and longer exposures would be great .

Chris


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Re: CGEM motor cogging new [Re: Stew57]
      #5882448 - 05/24/13 02:32 PM

Yeah, I'd buy a retrofit kit of that, Stew57!

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WesC
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Re: CGEM motor cogging new [Re: Raginar]
      #5882453 - 05/24/13 02:34 PM

Quote:

Don't we need to see pictures over 480secs to prove that it's actually gone? Without it, you've just confirmed that it works within a worm gear cycle. I always had success at 5 minutes or so, I never got much beyond that.

Can you guys remove your reducers too? It'd be nice to see long focal length shots. 1000mm and longer exposures would be great .

Chris




Well, both of them said that they were never able to do exposures of this length before, so its definitely a huge improvement!


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EFT
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Re: CGEM motor cogging new [Re: WesC]
      #5882496 - 05/24/13 02:58 PM

Quote:

Yeah, I'd buy a retrofit kit of that, Stew57!




That's exactly why they have to take care of the issue with firmware. If there is a retrofit, it will not be free because it is not absolutely required. Thus, the most sensible way to handle things is to get the existing units fixed with an "easy" no-cost to the consumer firmware upgrade. Then, they can either sell a retrofit package or service for people that want that and change the future mounts if that ends up being desirable. The wisest choice was to come up with a firmware fix first that would cost the existing owners nothing to implement.


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Ron (Lubbock)
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Re: CGEM motor cogging new [Re: WesC]
      #5882506 - 05/24/13 03:02 PM

This image is a recent M101 comprised of 43 x 15 minute (900s) subs at 1280 mm. I have not upgraded to the new version of MC firmware- this was taken with the old software. You've just got to absolutely eliminate Dec. drift to get long subs. with a CGEM. I would also be suspicious of anyone who uses a guide scope and blames their CGEM for elongated stars. Some of these people may be disappointed when they upgrade the MC firmware and find out that their stars are still elongated.



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gmartin02
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Re: CGEM motor cogging new [Re: Raginar]
      #5882741 - 05/24/13 05:22 PM

Quote:

Don't we need to see pictures over 480secs to prove that it's actually gone? Without it, you've just confirmed that it works within a worm gear cycle. I always had success at 5 minutes or so, I never got much beyond that.




Chris, The firmware fix is to correct an issue with Dec guiding. Dec guiding issues have nothing to do with worm gear cycles.

Quote:


Can you guys remove your reducers too? It'd be nice to see long focal length shots. 1000mm and longer exposures would be great .

Chris



My picture of M81 above was shot with a reducer on a telescope with a native 1625mm focal length - the reducer effectively shortens the focal length to about 1090mm (over 1000mm). The pictures were 400 seconds (6 minutes & 40 seconds), which are the longest I have tried so far, but I plan to try longer images in the future.

Greg


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Ron (Lubbock)
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Re: CGEM motor cogging new [Re: gmartin02]
      #5882795 - 05/24/13 05:49 PM

The M101 image above was taken at about 1280 mm, which is easy on my mount with proper polar alignment. I have done imaging at 2000 mm with the old firmware, but it was difficult, with frequent lost guide stars in Ph.D. guiding. I hope the new MC will make 2000 mm a reality for me so I can do more small targets.

Good news: I was able to upgrade to MC v 31.15 this afternoon, and I will try it out this weekend. The problem was an Ativa USB-RS232 adapter that had trouble communicating with the hand controller. I am told there are many of these USB-serial cables out there that won't work for the firmware update because the drivers don't talk to the CGEM hand controller properly. Be aware of that before buying one online. I got the other adapter from AstroGadgets.com and it works fine. The Ativa cable is going back to the local store where I bought it.


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cn register 5
scholastic sledgehammer


Reged: 12/26/12

Re: CGEM motor cogging new [Re: Ron (Lubbock)]
      #5882877 - 05/24/13 06:41 PM

Don't forget to provide feedback on your experiences with the beta upgrade - good or bad - to the Celestron beta site. Apparently the vast majority of people who have downloaded the software have not done so.

Chris


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Raginar
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Re: CGEM motor cogging new [Re: Ron (Lubbock)]
      #5883728 - 05/25/13 10:34 AM

Ron,

That's beautiful. Nice medium focal length image of M101.

Greg,
I misunderstood my CGEM then. So you're telling me that 8/3 harmonic issue is not due to the worm gear cycle? Or is that still there and this just fixes the 'sawtooth' many of us experienced in dec?


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Ron (Lubbock)
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Re: CGEM motor cogging new [Re: Raginar]
      #5883754 - 05/25/13 10:46 AM

I got a chance to try MC v 31.15 last night. It was windy as heck and I only had 30 minutes to try it out before clouds rolled in, so I can't wait for a better night to do a more thorough assessment. However, here's my first impression.

I deliberately misaligned the scope enough that I would expect a pretty bad sawtooth pattern with a period of maybe 2-3 minutes. Not only was there no sawtooth in three different parts of the sky, but the RMS value of the Dec. guiding was ridiculously low! Dec. guiding is indeed noticeably smoother and quieter than RA guiding, as Derik from Celestron mentioned over on their site. The slewing of the scope is also smoother. There was no change to the RA guiding or its RMS value, except that it settled down after a few minutes and wasn't disturbed by skips in the Dec. guiding. I think I'm going to enjoy imaging with this mount a lot more now.

I'll wait for a second imaging session under better conditions, then post my assessment over on the Celestron beta tester site.


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gmartin02
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Re: CGEM motor cogging new [Re: Raginar]
      #5884282 - 05/25/13 04:19 PM

Quote:

Greg,
I misunderstood my CGEM then. So you're telling me that 8/3 harmonic issue is not due to the worm gear cycle? Or is that still there and this just fixes the 'sawtooth' many of us experienced in dec?



Hi Chris,
This explanation may not be the best, but here goes: The "8" is the period of rotation of the worm gear. The 8/3 harmonic issue is due to gear ratio of the first spur gear to the worm gear. This is inherent to the design of the gearbox, and has nothing to do with firmware. This design makes it very hard to train PEC for the mount because there are 2 different "significant" periodic errors (the 8 minute one and the 3 minute one), it can cause quite a large "total" periodic error, and one that is not consistent worm cycle to worm cycle. Also, some mounts show more error in one of the other periods than others, so the problem may be worse on your mount than in others mounts.

I think the only way this could be corrected would be with a gearbox replacement with a 1 to 1 gear ratio between the worm gear and the first spur gear (and MC board/motor replacement to match the new gear ratio).

Note: This 1 to 1 worm/spur gear ratio has already been done in the newly released AVX mount. I would guess that Celestron will eventually release a new version of a CGEM class mount with this gear ratio, thereby eliminating the problem.

Celestron has not announced if they are going to spend the time & money to make an upgrade package to fix the already released CGEM mounts. Since they know about the problem and have customers complaining about it, in the perfect world they would make an upgrade package to correct this, but that would be a lot of engineering time and money spent on an existing mount that could be used instead to apply to a new mount (with other improvements as well). Also, it is not just a case of replacing the hardware in the existing mount - once the new hardware was in place, the MC firmare would also have to be changed to match the new hardware, tested extensively, and tuned before the mount would work with the new hardware - again, even more time and money. We will have to wait & see on this one for the existing mounts.

All that being said, the slopes of the periodic errors are fairly smooth, so they should be able to be guided out as long as the guiding corrections are issued ofter enough (every couple of seconds).

For long exposure times at longer focal lengths, there are a lot of other things that can prevent images from producing round stars. Things like seeing conditions, non-periodic mount errors, quality and sensitivity of the guide camera, guide scope focal length, appropriate selection of guide star, guiding software setup, flexure between guide scope & imaging scope, etc., etc., etc.

Probably the biggest culprit of the above for long focal lengths is flexure between guide scope & imaging scope. The best way to deal with this is to use an off axis guider with a high quality guide camera. I am currently getting some flexure between my AT8RC & my guide scope when imaging directly overhead - this is only significant enough to ruin images when the scope is pointed within about 15 degrees of the zenith, so with my current setup I avoid targets that will enter this area. The very first thing on my shopping list is to get the SX Lodestar guide camera and the TS-OAG9 off axis guider to eliminate flexure problems.

In summary, then 8/3 problem is still there - the new beta firmware fixes the "sawtooth" in Dec issue (that was preventing me from getting any usable images with long focal length scopes).

Anyone that knows has a better explanation of the 8/3 issue - feel free to correct any inaccuracies in my above post.

Final notes:

In general, I think it would be hard for any manufacturer to make a really, really accurate mount for AP at the price point that these mounts are being offered for. At these price points, many engineering and manufacturing compromises need to me made, and the mounts are too inexpensive to spend the time testing and tuning each mount individually. You get what you pay for - that why Astro-Physics mounts cost so much more: High quality (expensive) motors, more time spent machining, and individual mount testing/tuning before shipment. I would be shocked if any company (including Astro-Physics) could produce a mount for under $2000 that could handle a 30-40 pound imaging load and be super accurate for AP.

Greg


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svtdoug
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Re: CGEM motor cogging new [Re: Raginar]
      #5884377 - 05/25/13 05:20 PM Attachment (14 downloads)

Quote:

Don't we need to see pictures over 480secs to prove that it's actually gone? Without it, you've just confirmed that it works within a worm gear cycle. I always had success at 5 minutes or so, I never got much beyond that.

Can you guys remove your reducers too? It'd be nice to see long focal length shots. 1000mm and longer exposures would be great .

Chris




Hi Chris,

My image of M51 on the previous page was taken without a focal reducer - at the full 2000 mm fl for the C8.

I've also imaged at 600 seconds with the firmware fix. This image was taken 4/11/13 at Camp Delany, with v30.91 of the beta firmware, using an Orion 8" Astrograph at 800mm fl. It consists of 12 - 10 min frames for 2 hrs total. Granted, its shorter focal length. The photo is also cropped about 60%.

Greg - nice images! And nice explanation of how the firmware fits in.

One other note - just to set the record straight: The majority of CGEM users have never had this dec guiding problem, your motors were manufactured correctly. For those people, great, this firmware is not a big deal, and it is possible to get great images without upgrading. But for those who have this dec cogging issue, myself included, it has made imaging extremely difficult and frustrating. For us folks, this firmware fix is very good news, is very welcome, and gives new life to our CGEM's. We are very grateful that Celestron has addressed this issue.

Doug


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Stew57
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Re: CGEM motor cogging new [Re: gmartin02]
      #5884523 - 05/25/13 06:51 PM

You close with your explanation. For every 3 exact rotations of the worm gear the spur turns 8 exactly. Form many mounts the 8/3 rerror is very large. For some mounts this error is greater than the worm pe. The problem guiding for some is the 8/3 error is far from smooth. With an integer gear box or a 3 worm rotation PEC it would help immensely. I have been able to use the work arounds for the cogging but the 88/3 error gets me. Besides unguided video would be nice if the pec would work.

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Re: CGEM motor cogging new [Re: Stew57]
      #5885356 - 05/26/13 10:43 AM

Grey/Mark,

Thanks . For some reason I thought the two were intertwined and I guess I hopped the firmware would fix it for ya'll.

Doug,

That's beautiful. Mechanical issues or not, that's something to be proud of .


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Ron (Lubbock)
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Re: CGEM motor cogging new [Re: Raginar]
      #5892262 - 05/30/13 12:03 PM

I was able to spend a few more hours with the new MC firmware last night, and the results were less promising this time. The Dec. cogging issue is not gone on my mount, it turns out. If there is any misalignment in Dec., the sawtooth pattern is still there, as bad as ever. I was only able to get rid of it by doing accurate drift alignment. That being said, the mount worked really well when I did get it drift aligned, and the RMS value in PhD was as low as I've ever gotten it.

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Re: CGEM motor cogging new [Re: Ron (Lubbock)]
      #5892547 - 05/30/13 02:09 PM

Was this the beta firmware from teamcelestron? If so post on the site as feedback is needed. If it a release version there is no cogging fix present.

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Ron (Lubbock)
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Re: CGEM motor cogging new [Re: Stew57]
      #5892669 - 05/30/13 03:09 PM

It is beta version 31.15 and my findings have been posted on teamcelestron. Derik says I am the first lucky person to observe cogging with 31.15.

Edited to add: I was able to do a 4 hr. session a couple nights ago, and I did a very accurate polar alignment. I did not have any Dec. cogging during the whole session. Thus, I am thinking that the sawtooth pattern requires poor polar alignment. I am pretty happy with the way my mount is functioning right now, despite the trouble on the one night.




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jrbuete
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Re: CGEM motor cogging new [Re: Ron (Lubbock)]
      #5926652 - 06/17/13 11:58 PM

Just got a CGEM 1100HD a few months ago and noticed some issues with a movement in the eyepiece about every second while viewing objects... depending on the sky location is was either unnoticeable or annoying... just did the check posted above and yep... looks like the cogging issue but one question:
Is it normal for it only to be in one direction? I could get it to have several times per ' going up but going down, never a hitch...

Guess I'm waiting for the firmware before more pics... oh well..


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orlyandico
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Re: CGEM motor cogging new [Re: jrbuete]
      #5926671 - 06/18/13 12:11 AM

if your drift alignment is very good, and you're not getting any DEC corrections, then you wouldn't see any cogging because there wouldn't be any DEC corrections...

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rmollise
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Re: CGEM motor cogging new [Re: jrbuete]
      #5927134 - 06/18/13 09:56 AM

Quote:

Just got a CGEM 1100HD a few months ago and noticed some issues with a movement in the eyepiece about every second while viewing objects... depending on the sky location is was either unnoticeable or annoying... just did the check posted above and yep... looks like the cogging issue but one question:
Is it normal for it only to be in one direction? I could get it to have several times per ' going up but going down, never a hitch...

Guess I'm waiting for the firmware before more pics... oh well..




Are you saying you are observing visually? If so, this is another problem and you need to contact Celestron. Dec cogging only affects the dec axis when corrections are being applied to it. During normal tracking, NOTHING happens with the dec axis. The motor does not move.


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EFT
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Re: CGEM motor cogging new [Re: jrbuete]
      #5927297 - 06/18/13 11:21 AM

Quote:

Just got a CGEM 1100HD a few months ago and noticed some issues with a movement in the eyepiece about every second while viewing objects... depending on the sky location is was either unnoticeable or annoying... just did the check posted above and yep... looks like the cogging issue but one question:
Is it normal for it only to be in one direction? I could get it to have several times per ' going up but going down, never a hitch...

Guess I'm waiting for the firmware before more pics... oh well..




I agree that this is not likely the DEC cogging issue. Since it is happening while "going up" it is likely that it is a balance and stiction issue. If the axis is not well balanced, then when the mount is struggling to move up against the off-balance, the axis can begin to show signs of sticking due to the force being applied to the worm and ring gear. Essentially, the faces of the worm and ring gear are being pushed together hard enough to cause them to stick slightly and then quickly release giving you little jumps. When going the other direction, the mount is no longer struggling and as a result may move more smoothly. If this were happening in both directions, then the issue would most likely be one of worm and ring gear spacing. But when it only happens in one direction, it is almost always a balance issue.


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Raginar
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Re: CGEM motor cogging new [Re: EFT]
      #5927374 - 06/18/13 11:53 AM

I was going to guess balance too.

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jrbuete
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Re: CGEM motor cogging new [Re: Raginar]
      #5928275 - 06/18/13 09:18 PM

Thanks! I'll pay particular attention to my balance this weekend and see what happens, I know I was off a little bit since I balanced with my DSLR and then was doing visual at the end so...

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Stargazer78
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Reged: 03/05/13

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Re: CGEM motor cogging new [Re: jrbuete]
      #6057081 - 09/01/13 04:13 AM

I think I am experiencing this issue

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Raginar
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Re: CGEM motor cogging new [Re: Stargazer78]
      #6057504 - 09/01/13 11:41 AM

I didn't think the DX suffered this problem.

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