Jose Corazon replied to the topic 'Re:Celestron focus motor' in the forum. 3 years ago

mhammady wrote:

El Corazon wrote:

mhammady wrote:

Bart wrote: Hi mate,
I have 3D printed a focus motor attachment & coupler for my C8.
I've shared a photo of my setup before here, I guess you can find it there.
What I like is that it still has a (big!) handwheel.

Would you like to have the design?
It uses a direct drive very flat Nema 17 stepper motor and the SilentStepper drivers (TMC2130) on a breadboard still.

Works flawlessly and runs absolutely smooth. I have attached a temp sensor and configured it to play well with the Moonlite protocol.

Cheers!
Bart



Hi Bart, thank you and would appreciate if you can share your 3D designs. I’m in the process of building mine.

One more thing is that your motor is much lighter and smaller (as I can tell from pictures) from the one I got, can you please also share your hardware specs as well?


Thank you
Mohamed



I use the MyFocuserPro, not the MyFocuserPro2 IDE, but assume much of it is interchangeable. The cranking power of a regular NEMA17 is plenty to lift a truck attached to a camera (figuratively speaking). A NEMA14 should be plenty. You can drive both from a DRV8825 stepper controller.

The beauty of building your own focuser is that once you have done it once, adapting it to another telescope is easy.

Also, with a DRV8825 you will have a stepper resolution of 6400 steps/rev, i.e. ~ 0.05 degrees, which more than likely is far better than the mechanical tolerance of your focuser.

All I can say is, I built one based on the MyFocuserPro (not 2) instructions and the result could not possibly (repeat; possibly!!) be better.

Jo

PS: Looks like Bart is using a slim version of the NEMA17 ( smile.amazon.com/gp/product/B00PNEQ79Q/r..._title?ie=UTF8&psc=1 ). I have that as well, but have not implemented it yet. Should work fine, though, I assume.


Thank you Jo, what confuses me a little is that the specs of the motor you mentioned in Amazon is “This is Short Height Bipolar Nema 17 stepper motor with 1.8 deg. step angle (200 steps/revolution). “

Is this specs still capable of 0.05 degree/step?

I would prefer using a lighter motor as the one I got is much heavier...


Thank you
Mohamed



The DRV8825 stepper controller allows you to select microstepping down to 1/32, i.e. 32x200=6400 steps/rev. In fact, you can use any microstepping mode in 2x intervals.
I am using my NEMA17 at 1/32 microstepping and the resolution is far better than required for my telescope, so you can try out how much resolution you require.

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