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Author Topic: AstroEQ and cg4 dual axis motor drive  (Read 246 times)

lbim

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AstroEQ and cg4 dual axis motor drive
« on: March 22, 2019, 00:41:12 »

Thomas,
My CG4 dual axis motor drive controller box was destroyed in field accident. I bought AstroEQ USB telescope mount controller in September 2017 and didn't have many chance to got to know it better, life was not cooperating with that. Now I have CG4 mount, still operational two original step motors and my question.
Can I safely connect those motors directly to AstroEQ controller? Will it work and will not burn AstroEQ controller?
My knowledge about step motors is very limited, every bit of info is much appreciated.
I know that those motors (42PM48L are rebranded 42BY48L) are slow and not good for fast mount motion.
This is not a problem for now, I need to have proper tracking speed of mount. If this will work now I will spend more time and money to make it better later.
Need you assistance, please advise.
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TCWORLD

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Re: AstroEQ and cg4 dual axis motor drive
« Reply #1 on: March 22, 2019, 08:24:41 »

Hi,

No problem at all using the CG4 dual-axis kit - they are basically the same motors as the EQ5 DA kit which is what the AstroEQ was originally designed for.

I believe the settings for the EQ3-2 Skywatcher Type 1 or Type 2 should work (not sure which one).

Kind Regards,
Tom
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Tom Carpenter (AstroEQ)

lbim

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Re: AstroEQ and cg4 dual axis motor drive
« Reply #2 on: March 25, 2019, 16:06:36 »

Hello Tom,

Thank you very much and appreciate your quick respond.
It is a good solution for now, and in case when I will upgrade (it will be soon) step motors could you suggest what motors should I use?
I am thinking of geared motors to avoid belts and wheels, have limited conditions to do mechanical works.
Promise not bother you to much with many questions.

Regards,
LBIM
 
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lbim

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Re: AstroEQ and cg4 dual axis motor drive
« Reply #3 on: April 14, 2019, 15:27:34 »

Any suggestions to my question above? Anybody?
Need some directions for what kind of motors and where to look.
Any words of recommendation are greatly appreciated.
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jslight

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Re: AstroEQ and cg4 dual axis motor drive
« Reply #4 on: April 19, 2019, 05:11:55 »

I am using NEMA17 stepper motors that work great on my Celestron CG-4.  You can use them with either gears or belts/pulleys (the latter is recommended to reduce backlash).  NEMA14 motors would also work (smaller size).

Stepper specs (from https://www.astroeq.co.uk/tutorials.php?link=custommotors):
  • Rated Current: <1.2A per Phase
  • Rated Voltage: Lower voltage generally have higher torque, but can cause stuttering. Higher voltage (max 12V) will reduce stuttering issues.
  • Inductance: again, lower is better. Look for something <10mH per phase
  • Step Angle: typically 1.8 degrees or 0.9 degrees.

Based on my experience with my motors (5.4V), I would recommend finding motors with a voltage rating close-ish to, but lower than, the voltage supply you are using (e.g. ~9-11.5V motors w/ 12V supply); you don't need the extra torque with a CG-4.  Also, I would recommend using 0.9 steppers if you are doing lots of astrophotography, 1.8 steppers if you want higher top speeds.  OMC Stepper Online has a good selection.

Probably the more difficult part is making the mounting brackets; personally, I just cut pieces of L-angle aluminium and drilled holes (easy  ;D).
« Last Edit: April 19, 2019, 05:56:28 by jslight »
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lbim

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Re: AstroEQ and cg4 dual axis motor drive
« Reply #5 on: April 20, 2019, 00:33:06 »

jslight,

I am very grateful for your detailed information, really appreciate this.
In my recent setting the AstroEQ with dual-axis steppers kit is working as advertised, have no problem at all.
It is enough for good tracking and when I've try to use it as goto mount it shows that steppers upgrade is necessary. Your respond will help me to get there sooner than later.
Once more thanks a lot.

LBIM
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