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  1. #1
    I have just finished a new build, Though all axis are moving as required the steppers are getting very hot, even with minimal movement.
    The steppers are Nema 23s 4.2 amp, they do not seem to be struggling at all. Any help with this would be highly appreciated. Thanks

  2. #2
    Steppers draw full current at idle.

    Unless you have a driver that reduces current at idle and that function is enabled.

    Are you sure you have the current settings correct?

    What driver?
    What voltage?

    Have you measured the temperature?

    Steppers can run hot, over 80c without issue.

  3. #3
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 6 Hours Ago Has been a member for 8-9 years. Has a total post count of 1,637. Received thanks 291 times, giving thanks to others 10 times.
    I was surprised at how hot steppers run - problem is that they need to draw power even when stationary to hold position. As said above, most stepper drivers have a "half-current" option that reduces current to half when the motor is stationary for more than a second or so, which reduces heating considerably. I aim to have my motors run at about "just not quite too hot to hold", which is around 60C.

    I start with the nominal rated current of the motor, based on its spec, and set the driver accordingly. I then adjust the max current so that in normal use the motor ends up at about the temperature as mentioned. There's a lot of discussion around things like peak/average/RMS current and what the driver settings mean. These discussions usually end up with a general conclusion of "search me, Guv!" as no-one is quite sure what the driver and the motor manufacturers are specifying. Hence the rule of thumb, "adjust so it's at about the right temperature."

  4. #4
    Quote Originally Posted by Neale View Post
    I was surprised at how hot steppers run - problem is that they need to draw power even when stationary to hold position. As said above, most stepper drivers have a "half-current" option that reduces current to half when the motor is stationary for more than a second or so, which reduces heating considerably. I aim to have my motors run at about "just not quite too hot to hold", which is around 60C.

    I start with the nominal rated current of the motor, based on its spec, and set the driver accordingly. I then adjust the max current so that in normal use the motor ends up at about the temperature as mentioned. There's a lot of discussion around things like peak/average/RMS current and what the driver settings mean. These discussions usually end up with a general conclusion of "search me, Guv!" as no-one is quite sure what the driver and the motor manufacturers are specifying. Hence the rule of thumb, "adjust so it's at about the right temperature."
    Hi Guys thanks for the replies. I ran the machine in idle this morning, the temp rose slowly over a 45 minute period, until it reach almost unholdable state, thats is as far as I got. The X motor which is smaller that the others got barely warm.
    POwer supply is 36 volts, the drivers are DM542, the Motors are rated at 4.2 amps. I am almost sure I set them at halve current setting. I will open up the case and have a look.

  5. #5
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 13 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,709. Received thanks 328 times, giving thanks to others 8 times.
    Stepper motors will quite happily run at 80degC.
    Not being able to hold your hand on them after 45 minutes isn't of any concern. If they were getting that hot within 10-15minutes, I'd be concerned, but not after 45 minutes.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  6. #6
    Quote Originally Posted by erniehatt View Post
    Hi Guys thanks for the replies. I ran the machine in idle this morning, the temp rose slowly over a 45 minute period, until it reach almost unholdable state, thats is as far as I got. The X motor which is smaller that the others got barely warm.
    POwer supply is 36 volts, the drivers are DM542, the Motors are rated at 4.2 amps. I am almost sure I set them at halve current setting. I will open up the case and have a look.
    Sounds like a Longs or Wantai drive kit.
    Had the same characteristics on my old X2. All still works.
    I put it down to the highish inductance of the cheapish motors.
    It's not like you can set the driver current too high for them and burn them out!.

  7. #7
    Quote Originally Posted by dazp1976 View Post
    Sounds like a Longs or Wantai drive kit.
    Had the same characteristics on my old X2. All still works.
    I put it down to the highish inductance of the cheapish motors.
    It's not like you can set the driver current too high for them and burn them out!.
    There's no heat generated in inductance, but higher inductance might be due to a larger number of turns of finer gauge wire which will increase the resistance of the winding as well. Heat is generated in resistance (RMS Amps squared x Ohms) so there might be a relationship there. Motor specs include the resistance as well as inductance so you could make a subjective comparison of which motor might run hotter for a given current, but there are other factors that will affect the true RMS current drawn by the motor anyway. As always there are several worms in every can!
    Last edited by Kitwn; 2 Weeks Ago at 03:34 AM.
    An optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.

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