I'm hoping to gain more knowledge, share some knowledge, and maybe provide a useful post for people to reference in the future.
I see a lot of people talking about how to cool their motors and questions about is it OK to let them get so many degrees warm. I have NEMA 17 steppers on my Prusa I2 that are 68 oz in. They are being driven by A4988 pololus. Once I learned how to set v-ref and added a second PC power supply to my printer, my axis have never missed a step. The 2nd supply was necessary because either the first cheap one wasn't delivering all the amperage it said it could or my printer was pulling more power than spec, so I now have a 2nd supply running my heat bed.
All of that said, my motors have NEVER got hot. Both of my Z motors always feel room temp metal cold. E is only slightly above Z in temp. You have to leave your finger on there for ten seconds to even notice the difference. My X and Y are just slightly above room temp. They feel like a coin you have been holding entirely enclosed in your hand for about thirty seconds. Try it, you'll see what I mean.
From reading and discussing with others there are only three reasons that I have come up with why steppers should get hot.
A. The driver (i.e. pololu) is turned up too high providing the motor with too much current.
B. The motor is too small for the application.
C. The axis the motor is attached to is providing too much resistance.
A is probably the only real reason, but people compensate for B and C by turning up the current (A).
I have read some research and white papers about micro stepping, from what I understand it is accomplished by fine control of current in the coils of the stepper motor. It applies more current to winding A than to winding B, so the shaft moves forward (toward winding B). Then it brings up the current on B while lowering the current on A until they are equal. At this point the shaft holds still. Ideally this was a uniform distance to the last micro step and is fraction of the distance a full step takes. Based on this fluctuation of even a milliamp in your system could cause inaccurate step.
Can anyone add or subtract from my list? Provide commentary or other on my understanding of micro stepping?
I see a lot of people talking about how to cool their motors and questions about is it OK to let them get so many degrees warm. I have NEMA 17 steppers on my Prusa I2 that are 68 oz in. They are being driven by A4988 pololus. Once I learned how to set v-ref and added a second PC power supply to my printer, my axis have never missed a step. The 2nd supply was necessary because either the first cheap one wasn't delivering all the amperage it said it could or my printer was pulling more power than spec, so I now have a 2nd supply running my heat bed.
All of that said, my motors have NEVER got hot. Both of my Z motors always feel room temp metal cold. E is only slightly above Z in temp. You have to leave your finger on there for ten seconds to even notice the difference. My X and Y are just slightly above room temp. They feel like a coin you have been holding entirely enclosed in your hand for about thirty seconds. Try it, you'll see what I mean.
From reading and discussing with others there are only three reasons that I have come up with why steppers should get hot.
A. The driver (i.e. pololu) is turned up too high providing the motor with too much current.
B. The motor is too small for the application.
C. The axis the motor is attached to is providing too much resistance.
A is probably the only real reason, but people compensate for B and C by turning up the current (A).
I have read some research and white papers about micro stepping, from what I understand it is accomplished by fine control of current in the coils of the stepper motor. It applies more current to winding A than to winding B, so the shaft moves forward (toward winding B). Then it brings up the current on B while lowering the current on A until they are equal. At this point the shaft holds still. Ideally this was a uniform distance to the last micro step and is fraction of the distance a full step takes. Based on this fluctuation of even a milliamp in your system could cause inaccurate step.
Can anyone add or subtract from my list? Provide commentary or other on my understanding of micro stepping?