Re: A new focuser motor on my 1-1/4" JMI RCF

Corey Mooney

Hi Howard,

You've inspired me to make some progress toward motorizing my focuser ( 8" EAA rig on an OnStep mount).
Thanks for the tip on the little geared stepper motors. I ended up ordering a couple of these 10mm 1:275 steppers
Your results are promising. 

Could be fun to try and make a mini 3D printed alt-az mount using these itty-bitty motors to drive little baby worms or GT2 pullies. 


On Fri, Nov 8, 2019 at 8:47 AM Howard Dutton <hjd1964@...> wrote:
I just finished off these two focusers.  They now both have RJ22 jacks inside the housing and so a detachable cable can plug them in.

I discovered two things during my final setup/testing:

1. The actual current I was sending to the tiny stepper motor was less than I thought, I didn't have the drivers set properly at Vref = 2.5V.  This is a good thing, the motors are not being overpowered and don't need to be run out of spec.  I now use the full rated current, peak = 276mA when moving and drop back to 80mA at standstill.

2. I spent about 3 hours figuring out that a socket header for the CS signal (spi bus) to focuser2 wasn't making contact.  It was a bad socket header LOL, was loosing my mind trying to figure that one out...  Tested good for continuity even since I was pressing on the pin with the meter lead.  Let the pressure go and it would loose contact.

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