Yet another stepper motor problem

[akonneker]

Hello all,

I've spent a while trying to figure out my problem and searching the forum for anybody with a similar experience, but no luck so far. My problem is thus:

I'm using the motor shield to drive a small 6-wire, unipolar, 0.9 degree/step NEMA17 stepper made by Lin Engineering. The problem is that only the microstepping seems to work. If I try any other mode in the 'step' function the motor just seizes. I'm pretty thoroughly confused.

I'm trying to run the motor off of the arduino USB supply, but I've also plugged in a 12V 1300mA rated power supply to the arduino DC jack with no difference.

Here is a link for the data sheet:http://www.alltronics.com/mas_assets/acrobat/28M053.pdf

Does anyone have any insights?

For perfect clarity here is my test code:

Code: Select all

#include <AFMotor.h>
AF_Stepper motor(200, 2);
void setup(){  }

void loop()
{ 
  motor.step(400, FORWARD, MICROSTEP);  //stops working if 'MICROSTEP' is switched to any other mode
  delay(300);
  motor.step(400, BACKWARD, MICROSTEP);
  delay(300);
}


[adafruit_support_bill]

From the specs, it looks like the motor was designed to be driven with about 14.4v, so your 12v supply should work better than the 5v you get from USB.

It is odd that only the microstepping works. Usually that it the mode that doesn't work if the motor is under-powered. You might try reversing the red/blue or green/black wires to see if it runs any better.

[akonneker]

I've tried all permutations of the non-common wires and running it on the 12V supply and there doesn't seem to be much difference. The shaft doesn't move at all, but the motor will vibrate slightly. This is my first experience with stepper motors, so I'm pretty mystified.
I'm getting a benchtop power supply in the next week or so, and I can try running it at the specified voltage, but I would expect that 12V should work if the microstep mode works on 5V.

For now I guess I'll be content with running it in microstep mode, since it seems to work quite smoothly. It's just so weird to me that it's the only thing that works.

[adafruit_support_bill]

I'm a bit puzzled too. A couple other things to try:

* Test the coil resistance to see if there are any internal shorts. The resistance from the common wire to the other two wires in each pair of coils should be fairly close to the same.

* Disconect the common wires (insulate the ends so they don't short on anything). This effectively makes your motor a bipolar stepper.