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BlackBox Motor Overheating

Discussion in 'Motors' started by dwh, May 1, 2019.

  1. dwh

    dwh New
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    The NEMA 17 stepper motors are running too hot from the BlackBox Controller. I have adjusted the axis current 'pots' fully counter clockwise against the stop. I tried the clockwise direction, but that only increases the heatup and cogging. There is more than adequate torque at this minimum setting, but the motors seem to be getting too much current, and I do not think they will last very long. The controller is used on a laser etcher using the X-axis, Y-axis, Y2-axis, and PWM/M3 signal.
    The system has accurate positioning and laser control, but has not been used very long in fear of damaging the stepper motors.
     
  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Where's the NEMA17s from? Blackbox at minimum outputs 1.0A - our NEMA17s are 1.7A.
    Heat is normal, putting a measurement to "hot" could help me judge if its problematic
     
  3. dwh

    dwh New
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    The steppers are standard duty that I have had for several years. A measurement of hot might be that they are too hot to touch after only 3-5 miutes, and hot enought to generate a scortching smell. This system has used other controllers without over heating and acutally staying cool for long periods of time. I may has some settings wrong, as I have just used most default settings. The system seems to function properly in displacement and laser control. If it would help to have a print out of the settings, I will try to get a listing.
    Thanks
     
  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Find the datasheet of your motors, who knows, maybe they are tiny little 700mA coils or something. BlackBox is 1Amp minimum (as our NEMA17s are 1.7A) - 1A is a good minimum for most motors, but with your unknown ones its hard to know. Or consider getting motors from us, then you know they are 1.7A 3.0V coil motors, which works great with BlackBox
     
  5. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Consider the old popular A4988 Pololu drivers, at max they put out 800mA (; BlackBox is a couple levels above that!
     
  6. sitoru

    sitoru New
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    what kind of speeds can you get from your steppers? right now I'm using some nema 17s from a delta 3d printer I took apart to use for my diy CO2 laser. They are rated for 1.7 but I think the torque is only 36 oz. I'm using them with my blackbox, but the other day I noticed they were getting hot. I can't seem to push them past 5000mm/min reliably.
     
  7. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Steppers are not inherintly 'fast' by nature. Also keep in mind Grbl's maximum steps per second limits
    - use larger tooth count pulleys
    - use lower microstepping
    - use higher torque motors
     
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  8. GS76

    GS76 Well-Known
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    I am glad I found this post.

    I have just received the Openbuilds Blackbox and the Openbuilds Nema17 stepper motors.

    I also noticed they are getting hot, but I am unsure if it is too hot. I have not adjusted the current pots or the grbl settings in the Openbuilds Control software.

    The temperatures I measured were as follows:

    1. 55 degrees after turning the system on. Measured after approximately 15 mins. Openbuilds Control software was not connected.

    2. 58 degrees. Measured after approximately 5 mins. Openbuilds Control software was connected. The "step idle delay" is set to 255 ms.

    3. 59 degrees. Measured after jogging the stepper back and forward for approximately 2 mins. Openbuilds Control software was connected. The "step idle delay" is set to 255 ms.

    Are these high temperatures?

    On another topic, where do I set the "micro-stepping" on the Blackbox?

    Thank you again for the help and the great products.
     
  9. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    See https://docs.openbuilds.com/blackbox/ > Section 2.2.1 deals with current adjustment, section 2.2.2 with microstepping (We don't recommend changing it)

    (The whole BlackBox documentation is worth a read,as is Home · gnea/grbl Wiki so you know how all the components work together and how Grbl (the firmware) works and is configured)

    Stepper motors do run hot. If its our NEMA17s, current adjustment pot turned all the way down is a good starting point - turn up a little if you have skipping
     
  10. GS76

    GS76 Well-Known
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    Hi Peter,

    Thank you for the reply. I will review the complete Blackbox documentation.

    Are the temperatures I measured excessive?
     
  11. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Where do you have the current set to at the moment?

    This is mentioned in the section 2.2.1 documentation as well.
     
  12. GS76

    GS76 Well-Known
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    Hi Peter,

    Thank you for telling me to read the Blackbox manual.

    I have found the following image for the wiring for the Nema17 motor to the Blackbox. See the link below.

    docs:blackbox:connect-nema17 [OpenBuilds Documentation]

    Is this how it should be wired, based on the colours of the wires?

    Thank you.
     
  13. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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  14. GS76

    GS76 Well-Known
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  15. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    If it was working before, and jogging the right directions, it was in order?

    There are 4 valid combinations that allow connection two coils to 4 pins - if you get it wrong it will not spin. If you get the combinations right but the order wrong it will work fine just reversed.
     
  16. GS76

    GS76 Well-Known
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    Thank you for this information, I was not aware.

    I will check this.
     
  17. sorin

    sorin New
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    Think I found the answer to my overheating issue too.
    I am using a 24V 0.6A stepper motor for my custom build z-axis, everything works great except that is overheating. This is the product name "T6 Mini Lead Screw Motion Stepper Motor Stroke Linear Guide Rail Slide Actuator 3D Printer Kit CNC+28 Step Motor50-200mm".

    These small linear rails do not seam to come in >1.0A versions. Is there any modifications I can do in order make this work? Maybe something to lower the minimum 1.0A to a 0.6A?
     
  18. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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  19. sorin

    sorin New
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    Thank you for your reply. Because of the specific application I am doing, need to reduce weight as much as possible on the z-axis.
    Short than replacing the stepper motor, I am assuming your reply means there are no modification that can be done?
     
  20. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Correct, its been designed from the ground up for power - typical of our machines - workhorses
     
  21. David the swarfer

    David the swarfer OpenBuilds Team
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    a Nema17 motor can have many different electrical characteristics for the same size and weight of motor, so you will be able to find a physically similar motor with a higher current rating, low voltage, and low inductance.
     
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