开云体育

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. Gemini_users
  2. Messages
Expanded Topics Messages Polls
Date
Re: Need advice on strange guiding problem

 

开云体育

I resent the image to your email, bypassing Google. ?Hopefully that will be readable.

As to the slipping.

1. Yes, I have checked the coupler
2. Clutches are tightish. ?I can make them move with come moderate pressure on them, but I can see how guiding changes could do it. ?I have previously tried this with clutches really tight and really loose. ?No real change.
3. As I mentioned in my original message, I have trid swapping the motors and well as the gearboxes (and as well the worms). ?No real difference.

It is a mystery.



On Sep 29, 2024, at 10:19?AM, Paul Kanevsky <yh@...> wrote:

It's nearly impossible to read the PE chart due to small scale. What I was interested in seeing was any sudden jumps, and especially those that don't repeat with the worm cycle (which requires more than one worm cycle to be recorded). PE looks OK from a very high level, but I really can't see the details in the image to be sure.
?
As to what else can be slipping:
?
1. Oldham coupler, as you already checked
2. Clutches
3. Encoder ring inside the servo (you can try swapping DEC and RA servos to see if the problem goes over to DEC)
?
Additionally, poor connection to the encoder(s), noisy or intermittent cable connection, or encoder damage / dirt on the encoder optical ring can all cause issues that look like something is slipping. I had one servo that was misbehaving. Turns out a small spider crawled through the external connector and put up some spiderwebs inside the motor that caused all kinds of strange problems :) Dirt or damage in the gearboxes can also cause erratic behavior.
?
For most of these, try swapping the components between RA and DEC to see what makes the problem switch to the other axis.
?
Regards,
?
? -Paul
?
On Sun, Sep 29, 2024 at 12:02 PM, Bill Tschumy wrote:
Paul (and others),
?
I’ve attached a screenshot showing the unguided results over about 18 minutes. ?You can sort of see the periodic error which I think is 478 seconds (about 8 minutes) for the GM8. ?I’m not sure what this tells us, but hopefully it will be useful.
?



I also noticed a curiosity last night. ?Ekos has a “Plate solve and center target” function. ?It will automatically repeat this until the error is less than some amount (30 arcsec in my case). ?Lately it seems to be having more trouble zeroing in on the target. ?Here is a screenshot of what it did. ?Rows 8 through 18 are its trying to zero in. ?Note that the declination zeros in nicely. ?However, the RA seems to oscillate by overshooting the center each time (assuming I’m reading this correctly). ?It oscillates between a positive error and a negative error.
?
?
It seem kind of surprising it would be overshooting in this case.
?
Back to the guided results I posted initially, it sort of feels like something is slipping. ?It tries to make a correction, but doesn’t get there (or possibly goes too far). ?The most likely thing I know of that could slip is the connection of the motor shaft and the worm shaft to the Oldham coupler. ?However, I’ve verified several times that the set screws are tight. ?I don’t see how that connection could be slipping. ? Is there any place else in the system where slippage could occur?
?
Bill

On Sep 28, 2024, at 3:41?PM, Bill Tschumy <bill@...> wrote:
Paul,
?
I should be able to get an unguided log tonight.
?
Yes, Gemini 1. ?The autoguider is connected to the main camera, which in turn is connected to a Raspberry Pi 4. ?The RPi4 also has a USB cable coming out that goes into the RS232 port on the Gemini 1 (via a USB to serial converter). ?Pretty sure I’ve tried the autoguider plugged directly into the RPi4, but I can try that again to see if if there are any differences.
?
Bill
?
--?
Bill Tschumy
Otherwise -- Longmont, CO
www.otherwise.com
?

--?
Bill Tschumy
Otherwise -- Longmont, CO
www.otherwise.com
Re: Need advice on strange guiding problem

 

It's nearly impossible to read the PE chart due to small scale. What I was interested in seeing was any sudden jumps, and especially those that don't repeat with the worm cycle (which requires more than one worm cycle to be recorded). PE looks OK from a very high level, but I really can't see the details in the image to be sure.
?
As to what else can be slipping:
?
1. Oldham coupler, as you already checked
2. Clutches
3. Encoder ring inside the servo (you can try swapping DEC and RA servos to see if the problem goes over to DEC)
?
Additionally, poor connection to the encoder(s), noisy or intermittent cable connection, or encoder damage / dirt on the encoder optical ring can all cause issues that look like something is slipping. I had one servo that was misbehaving. Turns out a small spider crawled through the external connector and put up some spiderwebs inside the motor that caused all kinds of strange problems :) Dirt or damage in the gearboxes can also cause erratic behavior.
?
For most of these, try swapping the components between RA and DEC to see what makes the problem switch to the other axis.
?
Regards,
?
? -Paul
?
On Sun, Sep 29, 2024 at 12:02 PM, Bill Tschumy wrote:

Paul (and others),
?
I’ve attached a screenshot showing the unguided results over about 18 minutes. ?You can sort of see the periodic error which I think is 478 seconds (about 8 minutes) for the GM8. ?I’m not sure what this tells us, but hopefully it will be useful.
?



I also noticed a curiosity last night. ?Ekos has a “Plate solve and center target” function. ?It will automatically repeat this until the error is less than some amount (30 arcsec in my case). ?Lately it seems to be having more trouble zeroing in on the target. ?Here is a screenshot of what it did. ?Rows 8 through 18 are its trying to zero in. ?Note that the declination zeros in nicely. ?However, the RA seems to oscillate by overshooting the center each time (assuming I’m reading this correctly). ?It oscillates between a positive error and a negative error.
?
?
It seem kind of surprising it would be overshooting in this case.
?
Back to the guided results I posted initially, it sort of feels like something is slipping. ?It tries to make a correction, but doesn’t get there (or possibly goes too far). ?The most likely thing I know of that could slip is the connection of the motor shaft and the worm shaft to the Oldham coupler. ?However, I’ve verified several times that the set screws are tight. ?I don’t see how that connection could be slipping. ? Is there any place else in the system where slippage could occur?
?
Bill

On Sep 28, 2024, at 3:41?PM, Bill Tschumy <bill@...> wrote:
Paul,
?
I should be able to get an unguided log tonight.
?
Yes, Gemini 1. ?The autoguider is connected to the main camera, which in turn is connected to a Raspberry Pi 4. ?The RPi4 also has a USB cable coming out that goes into the RS232 port on the Gemini 1 (via a USB to serial converter). ?Pretty sure I’ve tried the autoguider plugged directly into the RPi4, but I can try that again to see if if there are any differences.
?
Bill
?
--?
Bill Tschumy
Otherwise -- Longmont, CO
www.otherwise.com
?
Re: Need advice on strange guiding problem

 

开云体育

Paul (and others),

I’ve attached a screenshot showing the unguided results over about 18 minutes. ?You can sort of see the periodic error which I think is 478 seconds (about 8 minutes) for the GM8. ?I’m not sure what this tells us, but hopefully it will be useful.

PastedGraphic-1.png


I also noticed a curiosity last night. ?Ekos has a “Plate solve and center target” function. ?It will automatically repeat this until the error is less than some amount (30 arcsec in my case). ?Lately it seems to be having more trouble zeroing in on the target. ?Here is a screenshot of what it did. ?Rows 8 through 18 are its trying to zero in. ?Note that the declination zeros in nicely. ?However, the RA seems to oscillate by overshooting the center each time (assuming I’m reading this correctly). ?It oscillates between a positive error and a negative error.

PastedGraphic-2.png

It seem kind of surprising it would be overshooting in this case.

Back to the guided results I posted initially, it sort of feels like something is slipping. ?It tries to make a correction, but doesn’t get there (or possibly goes too far). ?The most likely thing I know of that could slip is the connection of the motor shaft and the worm shaft to the Oldham coupler. ?However, I’ve verified several times that the set screws are tight. ?I don’t see how that connection could be slipping. ? Is there any place else in the system where slippage could occur?

Bill

On Sep 28, 2024, at 3:41?PM, Bill Tschumy <bill@...> wrote:

Paul,

I should be able to get an unguided log tonight.

Yes, Gemini 1. ?The autoguider is connected to the main camera, which in turn is connected to a Raspberry Pi 4. ?The RPi4 also has a USB cable coming out that goes into the RS232 port on the Gemini 1 (via a USB to serial converter). ?Pretty sure I’ve tried the autoguider plugged directly into the RPi4, but I can try that again to see if if there are any differences.

Bill

--?
Bill Tschumy
Otherwise -- Longmont, CO
www.otherwise.com
Re: Help needed re: connecting Gemini 2 to PC

 

Paul,
Thanks for the advise and the links. I'm going to follow those instructions & hopefully everything will work okay.
?
Ron
Re: Help needed re: connecting Gemini 2 to PC

 

I don't know about TheSky6 and Nina, but my Raspberry Pi running Ekos connects to the Gemini II through the USB-b port.? Ekos uses serial connections for their drivers, in this case over USB, so the Gemini II clearly supports that.
?
Re: Help needed re: connecting Gemini 2 to PC

 

David,
Good to hear from you.? I am also a dedicated MI-250 user. I got mine from the original owner back in 2005, and it has performed perfectly ever since. My Gemini I that just got fried was the one that came with the mount back in 2005, so I guess I can't complain about it finally shooting craps. Can't think of another electronic device I bought in 2005 that is still working!
Thanks for yur advise.
Ron
Re: Need advice on strange guiding problem

 

开云体育

Paul,

I should be able to get an unguided log tonight.

Yes, Gemini 1. ?The autoguider is connected to the main camera, which in turn is connected to a Raspberry Pi 4. ?The RPi4 also has a USB cable coming out that goes into the RS232 port on the Gemini 1 (via a USB to serial converter). ?Pretty sure I’ve tried the autoguider plugged directly into the RPi4, but I can try that again to see if if there are any differences.

Bill

On Sep 28, 2024, at 3:09?PM, Paul Kanevsky <yh@...> wrote:

So the calibration looks good. How about an unguided tracking log over a few worm cycles?
?
This is with Gemini-1, correct? How is your autoguider connected to Gemini?
?
Regards,
?
? -Paul

On Sat, Sep 28, 2024 at 12:44 PM, Bill Tschumy wrote:
Paul,
?
I have calibrated and re-calibrated many, many times. ?I have also tried a variety of different pulse lengths for calibration. ?If calibration is off then there must be some other fundamental problem that is causing it. ?I’ve attached the Calibration Plot that Ekos generates. ?It doesn’t look particularly bad to me.
?
I do use a somewhat longer pulse length (around 1250 ms) because if I do shorter the Dec calibration looks worse.
?
?
?
Sometimes the Dec calibration dots can be a bit squirrely although the ones here look fine to me.
?
I should also mention that I’ve tried adjusting the RA worm play ad nauseum and that doesn’t seem to help.
?
Bill

On Sep 28, 2024, at 9:22?AM, Paul Kanevsky <yh@...> wrote:
Hi Bill, it looks like to me that the autoguider isn't calibrated properly. Corrections are often insufficient in RA, and sometimes overshoot a quick jump. The first step is to measure your periodic error during tracking (capture a few cycles of tracking error while not guiding). See what tracking looks like without autoguider corrections. Then, a guide log may help diagnose what's going on while guiding is engaged. PHD2 also has a number of diagnostic/calibration tools that may help figure out what's going on.
?
Regards,
?
?-Paul
?

--?
Bill Tschumy
Otherwise -- Longmont, CO
www.otherwise.com
?

--?
Bill Tschumy
Otherwise -- Longmont, CO
www.otherwise.com
Re: Need advice on strange guiding problem

 

So the calibration looks good. How about an unguided tracking log over a few worm cycles?
?
This is with Gemini-1, correct? How is your autoguider connected to Gemini?
?
Regards,
?
? -Paul

On Sat, Sep 28, 2024 at 12:44 PM, Bill Tschumy wrote:
Paul,
?
I have calibrated and re-calibrated many, many times. ?I have also tried a variety of different pulse lengths for calibration. ?If calibration is off then there must be some other fundamental problem that is causing it. ?I’ve attached the Calibration Plot that Ekos generates. ?It doesn’t look particularly bad to me.
?
I do use a somewhat longer pulse length (around 1250 ms) because if I do shorter the Dec calibration looks worse.
?
?
?
Sometimes the Dec calibration dots can be a bit squirrely although the ones here look fine to me.
?
I should also mention that I’ve tried adjusting the RA worm play ad nauseum and that doesn’t seem to help.
?
Bill

On Sep 28, 2024, at 9:22?AM, Paul Kanevsky <yh@...> wrote:
Hi Bill, it looks like to me that the autoguider isn't calibrated properly. Corrections are often insufficient in RA, and sometimes overshoot a quick jump. The first step is to measure your periodic error during tracking (capture a few cycles of tracking error while not guiding). See what tracking looks like without autoguider corrections. Then, a guide log may help diagnose what's going on while guiding is engaged. PHD2 also has a number of diagnostic/calibration tools that may help figure out what's going on.
?
Regards,
?
?-Paul
?

--?
Bill Tschumy
Otherwise -- Longmont, CO
www.otherwise.com
?
Re: Need advice on strange guiding problem

 

开云体育

Paul,

I have calibrated and re-calibrated many, many times. ?I have also tried a variety of different pulse lengths for calibration. ?If calibration is off then there must be some other fundamental problem that is causing it. ?I’ve attached the Calibration Plot that Ekos generates. ?It doesn’t look particularly bad to me.

I do use a somewhat longer pulse length (around 1250 ms) because if I do shorter the Dec calibration looks worse.


PastedGraphic-1.png

Sometimes the Dec calibration dots can be a bit squirrely although the ones here look fine to me.

I should also mention that I’ve tried adjusting the RA worm play ad nauseum and that doesn’t seem to help.

Bill

On Sep 28, 2024, at 9:22?AM, Paul Kanevsky <yh@...> wrote:

Hi Bill, it looks like to me that the autoguider isn't calibrated properly. Corrections are often insufficient in RA, and sometimes overshoot a quick jump. The first step is to measure your periodic error during tracking (capture a few cycles of tracking error while not guiding). See what tracking looks like without autoguider corrections. Then, a guide log may help diagnose what's going on while guiding is engaged. PHD2 also has a number of diagnostic/calibration tools that may help figure out what's going on.
?
Regards,
?
?-Paul
?

--?
Bill Tschumy
Otherwise -- Longmont, CO
www.otherwise.com
Re: Help needed re: connecting Gemini 2 to PC

 

?
The easiest way to connect to a Gemini 2 using Ethernet directly to a PC Ethernet port is to use Ethernet crossover cable or IME a crossover adapter with a standard CAT5/6 cable of appropriate length. I say this is easiest because even though the vast majority of computers these days have Ethernet ports that should automatically . detect what kind of connection they are talking to many people cannot successfully make a direct connection without using a crossover cable / crossover adapter or use a router to manage the connection.?
?
Also you can order and receive a crossover adapter from Amazon very quickly as well as a CAT5/6 patch cable as they are cheaper and involve a bit less setup to be successful than using a small router. Using router has its advantages but you may or may not have a use for what a router can bring to the table.? ?
?
--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astrospheric - South Pasadena?
Re: Need advice on strange guiding problem

 

Hi Bill, it looks like to me that the autoguider isn't calibrated properly. Corrections are often insufficient in RA, and sometimes overshoot a quick jump. The first step is to measure your periodic error during tracking (capture a few cycles of tracking error while not guiding). See what tracking looks like without autoguider corrections. Then, a guide log may help diagnose what's going on while guiding is engaged. PHD2 also has a number of diagnostic/calibration tools that may help figure out what's going on.
?
Regards,
?
?-Paul
?
On Sat, Sep 28, 2024 at 11:03 AM, Bill Tschumy wrote:

Group,

I have been trying to use a 14 year old GM8 mount (non-spring loaded worms; non-tucked motors) for variable star analysis. For this analysis, it is not essential that guiding is perfect, but I’d like to get it better than I’m currently achieving. This is with a small refractor of 740mm focal length.

The crux of the issue is that guiding in Dec seems to be reasonable (say 0.3 RMS”) but RA guiding is significantly worse (say 1.5 RMS”). I’ve attached a screen shot showing what the RA guiding looks like (blue is Dec; green is RA).




I am using KStars/Ekos for imaging and guiding but I get similar results if I use PhD.

The RA seems to bounce around somewhat chaotically. I do have pretty bad seeing where I’m located, but the fact that the Dec doesn’ bouce around as much indicates this in more than bad seeing.

I have been working on this problem off and on for some time. I have tried.

1. Stripping the mount and completely cleaning/relubbing it 2 or 3 times
2. Swapped the worm and worm blocks between RA and Dec axes
3. Swapped the gear boxes between RA and Dec axes
4. Swapped the motors between RA and Dec axes
5. Shimmed the RA gear box to correct a slight misalignment at the Oldham coupler
6. Tried lubricating the Oldham coupler
7. Shifted the counterweight around to make it East heavy and East light
8. Tried a different power supply

None of this has made a significant difference. I still get poorer guiding in RA.




Anyone have any ideas on what is going on and how I might fix this?

Thanks,
Bill

--
Bill Tschumy
Otherwise -- Longmont, CO
www.otherwise.com
Re: Help needed re: connecting Gemini 2 to PC

 

Hi Ron,
?
First, Serial/RS232 is fully supported by Gemini-2, not sure why you say it isn't. Ethernet is definitely a better way to go, if you want to get the best out of the PC->Gemini link. Is your PC connected to a WiFi or other (home?) network, in addition to being connected to Gemini? If so, there's a little PC networking configuration that may be required, in addition to using a cross-over Ethernet cable (or a switch/router) that's already been mentioned. Here are some instructions that may help:
?
?
?
Regards,
?
? -Paul
?
On Fri, Sep 27, 2024 at 10:16 PM, stargazer66207 wrote:

Hello group,
?
Recently my trusty old Gemini I shot craps after 19 yrs of faithful service. I had to upgrade to the new Gemini 2 and Hand Controller.
As you know, the old Gemini I connected to a PC via a Serial/R12 connector cable which plugged in to one of the RJ 12 sockets on the control box. This does not work on the new Gemini 2.
I decided I want to connect via an ethernet cable (Cat 5) directly from the Gemini 2 to the ethernet port on my PC.? I have now installed this.
My question is: Now that I have the connection, what are my next steps to make it operational so that I can use programs like The Sky 6 and N.I.N.A. to run my mount?? I am a Newbie to Gemini 2, so any assistance you experienced Gemini 2 users can give me will be greatly appreciated! Thanks.
Ron Abbott
Need advice on strange guiding problem

 

Group,

I have been trying to use a 14 year old GM8 mount (non-spring loaded worms; non-tucked motors) for variable star analysis. For this analysis, it is not essential that guiding is perfect, but I’d like to get it better than I’m currently achieving. This is with a small refractor of 740mm focal length.

The crux of the issue is that guiding in Dec seems to be reasonable (say 0.3 RMS”) but RA guiding is significantly worse (say 1.5 RMS”). I’ve attached a screen shot showing what the RA guiding looks like (blue is Dec; green is RA).




I am using KStars/Ekos for imaging and guiding but I get similar results if I use PhD.

The RA seems to bounce around somewhat chaotically. I do have pretty bad seeing where I’m located, but the fact that the Dec doesn’ bouce around as much indicates this in more than bad seeing.

I have been working on this problem off and on for some time. I have tried.

1. Stripping the mount and completely cleaning/relubbing it 2 or 3 times
2. Swapped the worm and worm blocks between RA and Dec axes
3. Swapped the gear boxes between RA and Dec axes
4. Swapped the motors between RA and Dec axes
5. Shimmed the RA gear box to correct a slight misalignment at the Oldham coupler
6. Tried lubricating the Oldham coupler
7. Shifted the counterweight around to make it East heavy and East light
8. Tried a different power supply

None of this has made a significant difference. I still get poorer guiding in RA.




Anyone have any ideas on what is going on and how I might fix this?

Thanks,
Bill

--
Bill Tschumy
Otherwise -- Longmont, CO
www.otherwise.com

PastedGraphic-1.png
PastedGraphic-2.png

Re: Help needed re: connecting Gemini 2 to PC

 

It might work as you connected them, if one or both ports are auto switching,
?
More than likely, you will need a hub or switch connected between the two.
?
Another possibility is to use a "cross-over" patch cable, assuming you are not already using one.
?
Your post is coincidental to what I will need to do for my recent upgrade of an MI-250 mount from Gemini I to Gemini II.
?
?
Help needed re: connecting Gemini 2 to PC

 

Hello group,
?
Recently my trusty old Gemini I shot craps after 19 yrs of faithful service. I had to upgrade to the new Gemini 2 and Hand Controller.
As you know, the old Gemini I connected to a PC via a Serial/R12 connector cable which plugged in to one of the RJ 12 sockets on the control box. This does not work on the new Gemini 2.
I decided I want to connect via an ethernet cable (Cat 5) directly from the Gemini 2 to the ethernet port on my PC.? I have now installed this.
My question is: Now that I have the connection, what are my next steps to make it operational so that I can use programs like The Sky 6 and N.I.N.A. to run my mount?? I am a Newbie to Gemini 2, so any assistance you experienced Gemini 2 users can give me will be greatly appreciated! Thanks.
Ron Abbott
Re: North Dec button not working

 

Sorry me typing not thinking
?
No a 15 pin VGA will not work as it is 3 rows DB15.?? You need two rows DB15.?? You can buy longer versions of what you have but try to get 2m at least.??? Also ensure its "encapsulated" that is moulded in plastic.??? These cables were dime a dozen years back and can still be purchased from computer shops.?? But I do advise buying from reputable sources as the male pins and female sockets should have little small friction fingers that keep good positive contact.
?
I have seen cheap no names that the mfgr just "pinches the pin" so it has a metal deformation that makes the positive contact.?? This will wear out quickly.
?
FWIW.....I blame my typos on drugs...just outa hospital (2 days ago) for more metal work in my spine.?? I'm the only person that can fracture vertebrae that are already fused...hoping on a SPECT CT scanner bed!?? Urrrgggh!?? Such is life!
--
Brendan
Re: North Dec button not working

 

开云体育

Brendan,

Are you saying that a standard VGA cable will work? ?I have several of those laying around. ?

I don’t understand your comment about “Aldo”. ?Is that a particular manufacturer? ?Or is this a comment that VGA cables will not work?

Can you give me a link to one you know works?

Bill

On Sep 18, 2024, at 6:37?PM, Brendan <brenatlilydale@...> wrote:

Yes I replaced one for user recently. ?Same issue. ?But they fail near the pins so doing a jumper is not so easy. ? ?DB15 Male /Female 2m or a little more. ? ?Mouser or Digikey. ? There are plenty of places that sell these. ?

Be aware there are DB15 for vga monitors that Aldo havd15 pins and these will not fit due to pin config.?

cheers
--
Brendan

--?
Bill Tschumy
Otherwise -- Longmont, CO
www.otherwise.com
Re: North Dec button not working

 

Yes I replaced one for user recently. ?Same issue. ?But they fail near the pins so doing a jumper is not so easy. ? ?DB15 Male /Female 2m or a little more. ? ?Mouser or Digikey. ? There are plenty of places that sell these. ?

Be aware there are DB15 for vga monitors that Aldo havd15 pins and these will not fit due to pin config.?

cheers
--
Brendan
Re: North Dec button not working

 

开云体育

Sorry for the delayed answer. ?Yesterday I was playing with the mount and noticed the North button was working again. ?After a few experiments I found that it was indeed the cable between the HC and the Gemini unit that was going bad (René was right). ?If the cable is flexed one way it fails and if flexed the other it works. ?I could probably temporarily work around it by splinting the cable.

It doesn’t seem that Losmandy sells replacement cables for the Gemini 1 anymore. ?Anyone have an idea where to get one or a suitable substitute?

Bill

On Sep 17, 2024, at 9:26?PM, Chip Louie <chiplouie@...> wrote:

On Sat, Sep 14, 2024 at 06:35 PM, Bill Tschumy wrote:
Brendan,
?
Thanks for the additional info. ?I will test this tomorrow.
?
Bill
?
?
So, what happened??
?
?
--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astrospheric - South Pasadena?

--?
Bill Tschumy
Otherwise -- Longmont, CO
www.otherwise.com
Re: North Dec button not working

 

I had this exact same problem. I too thought it might be the HC. Turns out all I did was replace the button battery in the main Gemini box (not the HC). Replaced battery and all is well.
?
Scott
181 - 200 of 34055