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Trying a nema 11

bj jones
2016-03-19
2016-03-28
  • bj jones

    bj jones - 2016-03-19

    i have a nema 11 with the 27:1 gearbox part #11HS12-0674D-PG27
    while trying it with my pro2 controller @12v . i notice it runs quit abit HOTTER
    i have not measured the actual temp but you can not hold in you hand.
    its rated the same voltage as the nema 17,
    the nema 17 is just warm to the touch
    but the'nema 11 is HOT
    Should i not worry?
    should i drop voltage down to 6v ?
    should i just stick with the NEMA 17 ?
    the reason i am trying thr N-11 is i was trying to Lighten my setup

    http://omc-stepperonline.kancart.com/item_detail/133-Gear-Ratio-27-1-Planetary-Gearbox-Dual-Shaft-Nema-11-Stepper-11HS12-0674D-PG27

     
  • brownrb

    brownrb - 2016-03-19

    Hi BJ

    I see the ratings for the Nema11 as
    Rated Current/phase 0.67A
    Phase Resistance 5.6ohms
    Recommended Voltage 12-24V

    but for the Nema17
    Rated Current/phase 0.4A
    Phase Resistance 30ohms
    Recommended Voltage 12-24V

    5.6 ohms vs 30ohms, so yes the Nema11 is gonna run a LOT hotter than the Nem17 at the same current level.

    If you adjusted the current on an EasyDriver/DRV8825 to suit a Nema17, then decided to swap it for a Nema11, well its gonna be VERY HOT

    You will need to attach the Nema11, set to full steps with coil power ON, then measure the current in one phase of the stepper and set the pot so the measured current was 70% of 0.6A or arround 420mA

     
  • bj jones

    bj jones - 2016-03-20

    thanks robert, i forgot about adjusting the driver and voltage, that did the trick , i can hold it in my hand now, the NEMA 11 seems to have plenty of torque, its very light and small

     
  • brownrb

    brownrb - 2016-03-20

    Hu BJ
    glad that its running as you wanted now. I havent tried the NEMA 11, let me kmow how you find it once you've had it out under the stars, be very interested to hear how it performs for you.

    Cheers
    Robert

     
  • bj jones

    bj jones - 2016-03-28

    I was able to Test the Nema11 Under the Stars This week end.
    It performed very well. I use a Canon 6d with a BaaderComa Corrector and the Gear Hanges Upside down on my 8" Newt I use APT or BYEOS to Focus and the Nema11p27 held the weight of the camera gear.as well as the Nema27p27.
    After adjusting the voltage with the 8825DRV it runs nice and cool. i use Half Stepping so I'm at 1.2 microns per Half step
    the nema 11 with the 27:1 gearbox part #11HS12-0674D-PG27
    is Light weight and Small

     
  • brownrb

    brownrb - 2016-03-28

    Looks great BJ, well done. Very impressive with the belt drive. I would guesss you get a bit more reduction using that. Did you manual focus with live view in APT or use the auto focus? Ive played with APT a bit, but I have a one-shot color CCD and rarely use the Canon EOS now.

    Regards
    Robert

     
  • bj jones

    bj jones - 2016-03-28

    It took a few tries but i was finallly ablle to find a gear that match the diameter of my focus wheel 1.5"
    It is a 25 tooth. i was tring to stay as close to 1:1 as i could. i had a 1.8" dia pully and the movment was so fine i had to use +10 -10 buttons to see any change in focusing
    i was using manual focus, i have not tried auto focus i APT yet , will try soon

     

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