Hot steppers

Discussion in 'Calibration, Help, and Troubleshooting' started by Paul Seccombe, May 29, 2016.

  1. Paul Seccombe

    Paul Seccombe Well-Known Member

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    I've just run my first (Benchy) print after moving over to the Titan Hybrid config. All appeared Ok but I have noticed that the pancake stepper is mad hot (guessing over 100C) and this is after only 1h20 of operation. I have checked my stepper setting and it was a little high (620mV) so hopefully this was the issue but I was wondering if anyone else had had issues with the small steppers.

    I checked the X and Y steppers and they were quite warm but nowhere near as hot (50C maybe).
     
  2. elmoret

    elmoret Administrator

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    .62v is appropriate for a full size NEMA17. It is too much for a short stack NEMA17.
     
  3. Paul Seccombe

    Paul Seccombe Well-Known Member

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    Thanks @elmoret. I will be trying lower levels today. It would be interesting to know what others are using with their pancake steppers.
     
  4. Old_Tafr

    Old_Tafr Well-Known Member

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    Having just started to look at buying a couple of spare Pololu boards, the information you need to work out the voltage seems to be in two places.

    The data sheet for the NEMA17 and the information on the Pololu (4988 & DRV8825) which is here....

    http://reprap.org/wiki/Pololu_stepper_driver_board

    This contains the info you need to calculate the voltage to set if you know the value of the driver boards reference resistor.

    The doc mentions the board getting hot and interrupting the current and also motors getting hot, but not in any great detail.

    I would be interested to know which Pancake motor you use and what voltage setting you arrive at, based on the rated current of the stepper and the equations in the doc.
     
  5. Paul Seccombe

    Paul Seccombe Well-Known Member

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    I'm using these steppers for the Titans. They have a rated current of 0.7A. If the sensing resistor is 0.05 on my drivers then the 300mV I have them now set to is still over-rating them to 0.75A but nowhere near the 1.55A I was putting through them. At 0.75A they appear to be running quite happily and are running at the same type as temperature as the bigger steppers on the stages. I will continue to drop the current to see when they start to skip see where I get to.
     
  6. R Design

    R Design Well-Known Member

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    @Old_Tafr if you're starting from scratch (rather than the build manual for a series of identical printers) it's not so much about numbers as Tom explains....
     
  7. Stefan

    Stefan Well-Known Member

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    I'm running a 13Ncm pancake (the small one without a connector) and it is getting very hot too....
    until now it did not melt any thing :) but I am planning to decrease the current too.
     

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