Bad initial guiding on my AP600e


Worsel
 

Tom


I do not know about the 600, but A-P recommends a separate power supply for their recent mounts.

Bryan


Tom Blahovici
 

I guess it doesn't help that the temperature was at -10C.  Seems to get worse as the temperature goes lower. Last night it was only one exposure where I had this issue.  Last week, when the temperature was -15 I had quite a few more.
Is it possible the power supply contributed?  I have a powerwerx 30 amp switching supply but I power the whole imaging setup with it.  This includes a ASI6200, ASI290, Moonlight Nitecrawler and a dew heater.
Tom


Ram
 
Edited

I used this mount when I was getting started in AP.  I have since upgraded to a newer AP mount 
This mount has significant stiction on the DEC axis. This appears as backlash when you calibrate with PhD or any other software. But this isn't backlash in the true sense of the term. This mount uses plane bearings on the DEC axis that are quite sufficient for the payload but unfortunately suffers from stiction.
The mount will not move over several commands and then suddenly take off.  It has overcompensated now and will again have to be guided back.  And then it goes on oscillating. RA guiding is usually awesome but DEC guiding is a disaster. 

I do not know a good solution to the stiction issue, maybe a light lubricant on the DEC axis rather than a heavy one may help but it may introduce other issues. 

But there is a very easy workaround: Dont polar align too precisely.  Set phD to guide in only one direction on the DEC axis. When it is moving in only one direction, there is very little stiction. You will see your problems go away.


Emilio J. Robau, P.E.
 

Indeed,

 

If it ain’t broke, don’t broke it.

 

Emilio J. Robau. P.E.

Professional Engineer

Florida, Montana, North Carolina

www.robau-designs.com

 

Designs for Human Habitation and Environmental Conservation

Civil Engineering - Project Management – Permitting – Consulting  Ph: 239-206-8000 Direct: 239-204-4322

2770 Horseshoe Drive S, Suite 7, Naples, Florida 34104

 

This e-mail message is sent from Robau and Associates, LLC, and is intended only for the addressee. This message and any attachments may contain information that is confidential or privileged. Upon receipt of any electronic file/data from Robau and Associates, LLC, you are agreeing to the following: This file/data is for informational purposes only. It is the responsibility of the recipient to reconcile this electronic file/data with the actual project site conditions. Recipient agrees to indemnify and hold harmless Robau and Associates, LLC for any defects or errors in this file/data.  Unauthorized use, dissemination, distribution or copying of this e-mail and any attachments is strictly prohibited. If you have received this email in error, please notify the sender by reply e-mail and delete the message and any attachments.

 


Roland Christen
 

Adding simple backlash compensation is not something I recommend. It can very easily cause system instability in Dec. PHD2 has a new adaptive compensation that might work well, but you would need to go to their user group to find out if this fits your needs. If your guiding is good then i would leave it be.

Rolando



-----Original Message-----
From: Emilio J. Robau, P.E. <ejr@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Tue, Jan 19, 2021 9:16 am
Subject: Re: [ap-gto] Bad initial guiding on my AP600e

Roland,

A follow up on dec backlash.   So, I should be allowing PHD to measure backlash and then applying it accordingly?  I thought the recommendation was not to do that.   Even without it, I have excellent tracking.
 
Thanks
 
Emilio J. Robau. P.E.
Professional Engineer
Florida, Montana, North Carolina
 
Designs for Human Habitation and Environmental Conservation
Civil Engineering - Project Management – Permitting – Consulting  Ph: 239-206-8000 Direct: 239-204-4322
2770 Horseshoe Drive S, Suite 7, Naples, Florida 34104
 
This e-mail message is sent from Robau and Associates, LLC, and is intended only for the addressee. This message and any attachments may contain information that is confidential or privileged. Upon receipt of any electronic file/data from Robau and Associates, LLC, you are agreeing to the following: This file/data is for informational purposes only. It is the responsibility of the recipient to reconcile this electronic file/data with the actual project site conditions. Recipient agrees to indemnify and hold harmless Robau and Associates, LLC for any defects or errors in this file/data.  Unauthorized use, dissemination, distribution or copying of this e-mail and any attachments is strictly prohibited. If you have received this email in error, please notify the sender by reply e-mail and delete the message and any attachments.
 

--
Roland Christen
Astro-Physics


Emilio J. Robau, P.E.
 

Roland,


A follow up on dec backlash.   So, I should be allowing PHD to measure backlash and then applying it accordingly?  I thought the recommendation was not to do that.   Even without it, I have excellent tracking.

 

Thanks

 

Emilio J. Robau. P.E.

Professional Engineer

Florida, Montana, North Carolina

www.robau-designs.com

 

Designs for Human Habitation and Environmental Conservation

Civil Engineering - Project Management – Permitting – Consulting  Ph: 239-206-8000 Direct: 239-204-4322

2770 Horseshoe Drive S, Suite 7, Naples, Florida 34104

 

This e-mail message is sent from Robau and Associates, LLC, and is intended only for the addressee. This message and any attachments may contain information that is confidential or privileged. Upon receipt of any electronic file/data from Robau and Associates, LLC, you are agreeing to the following: This file/data is for informational purposes only. It is the responsibility of the recipient to reconcile this electronic file/data with the actual project site conditions. Recipient agrees to indemnify and hold harmless Robau and Associates, LLC for any defects or errors in this file/data.  Unauthorized use, dissemination, distribution or copying of this e-mail and any attachments is strictly prohibited. If you have received this email in error, please notify the sender by reply e-mail and delete the message and any attachments.

 


Worsel
 

Tom

PHD2's adaptive backlash compensation MAY be able to mitigate (not eliminate) that amount.  If not, you can try uni-directional Dec guiding.  See pages 28 and 29 of the PHD2 documentation.

Bryan


Tom Blahovici
 

Ok,
I thought I had it adjusted well.  I re-greased the mount a while ago, and used a dial indicator to determine the play. Ok, maybe I can set the direction of the final slew or delay Voyager for a longer period.
Or just wait for my AP1100! 
Tom


Roland Christen
 


If I look at the PhD guiding assistant it tells me I need 2300 ms of dec backlash compensation.  So is this related to Dec backlash?
Yes, this is exactly Dec backlash and is typical of this mount. You can try to adjust it out, but it's not an easy thing to do.

Rolando

-----Original Message-----
From: Tom Blahovici <tom.va2fsq@...>
To: main@ap-gto.groups.io
Sent: Mon, Jan 18, 2021 6:31 pm
Subject: [ap-gto] Bad initial guiding on my AP600e

Hi
I have run into something with PhD guider that I would like feedback here first before going to their forum.
I use Voyager, and the way this works and the problem is :
1) It does a precise goto to an object.  In other words it does a goto, then it plate solves and if the error is less than 18" it starts the PhD guiding.
2) On this first positioning, and the start of guiding, the dec axis plot is drifting down a lot.  You can see that there is a lot of corrections being made.  As the Dec drift gets worse than 2" of arc, Voyager aborts.
3) Voyager, restarts the guiding and then all is OK.  The overall guiding is better than 0.5" over 20 minutes.

If I look at the PhD guiding assistant it tells me I need 2300 ms of dec backlash compensation.  So is this related to Dec backlash?
I am using a CP4. 

Thanks for any insight.
Tom

--
Roland Christen
Astro-Physics


Tom Blahovici
 

Hi
I have run into something with PhD guider that I would like feedback here first before going to their forum.
I use Voyager, and the way this works and the problem is :
1) It does a precise goto to an object.  In other words it does a goto, then it plate solves and if the error is less than 18" it starts the PhD guiding.
2) On this first positioning, and the start of guiding, the dec axis plot is drifting down a lot.  You can see that there is a lot of corrections being made.  As the Dec drift gets worse than 2" of arc, Voyager aborts.
3) Voyager, restarts the guiding and then all is OK.  The overall guiding is better than 0.5" over 20 minutes.

If I look at the PhD guiding assistant it tells me I need 2300 ms of dec backlash compensation.  So is this related to Dec backlash?
I am using a CP4. 

Thanks for any insight.
Tom