Hello, we are working on building our own Polargraph from the design on the instructables.

Our machine consists of:
the adafruit stepper motors http://www.adafruit.com/products/324
arduino uno (sainsmart brand)
L293D motor shield (also sainsmart brand)
a variable voltage power supply for the motorsheild (currently on 6v)
working from a windows laptop using "Polargraph 1.7-1.6" and the "application.windows32"

I was able to get the arduino loaded up and the processing application working. It seems to communicate with the machine and I uploaded the following properties:
***************************************************
# *** Polargraph properties file ***
#Tue May 13 14:59:16 MDT 2014
controller.pixel.samplearea=10.0
controller.pictureframe.position.y=190
controller.pictureframe.position.x=190
controller.testPenWidth.startSize=0.5
controller.machine.colour=969696
machine.motors.mmPerRev=95.0
controller.window.width=1318
controller.frame.colour=C80000
controller.image.position.y=178
controller.image.position.x=178
machine.motors.accel=200.0
controller.image.height=119
controller.machine.serialport=0
controller.window.height=593
controller.maxSegmentLength=2
machine.penlift.up=180
machine.penlift.down=90
controller.page.position.y=119
controller.vector.scaling=100.0
controller.page.position.x=278
controller.pictureframe.width=95
machine.step.multiplier=1
controller.grid.size=75.0
controller.testPenWidth.endSize=2.0
controller.pictureframe.height=95
controller.page.colour=DCDCDC
controller.testPenWidth.incrementSize=0.5
controller.image.width=119
machine.motors.stepsPerRev=200.0
machine.pen.size=0.8
controller.page.width=237
controller.pixel.mask.color=00FF00
controller.machine.baudrate=57600
controller.vector.minLineLength=0
machine.width=793
controller.page.height=356
controller.vector.position.y=0.0
controller.background.colour=646464
controller.image.filename=
controller.vector.position.x=0.0
controller.homepoint.y=119.0
controller.guide.colour=FFFFFF
machine.motors.maxSpeed=600.0
controller.homepoint.x=396.0
controller.density.preview.style=1
controller.pixel.scaling=1.0
controller.densitypreview.colour=000000
machine.height=1047
*******************************************************
everything looks good and the green "polargraph ready" is on. I then set the homepoint and then clicked "move to point" to a random spot. the motors stirred to life, going in opposite directions and then one motor starts vibrating without moving. the other motor just turns jumpily and neither of them fully stop no matter what I do in the application. I have to unplug it from my computer to get them to stop. I unplugged everything, switched the motors on the motor shield. they still went the wrong way and acted the same way(one turning, one vibrating)

Any ideas on what is not right?

Hello! Welcome.

Looks like you're doing it all right to me. You have for 200 stepsPerRev set, but that is easily fixed later. If you find the motors are turning in the wrong direction, you can just swap the pairs of wires and that should sort that, so don't worry about that.

Yep the shaking and jigging isn't right. Have you tried any other sketches on it - Perhaps the examples from the AFMotor library would be a good start (https://github.com/adafruit/Adafruit-Motor-Shield-library). There isn't really anything in the code that would make that behaviour, but it would be good to isolate it to being a hardware issue.

Try running just one motor (disconnect the other entirely). When you swapped motors, did the jumpy behaviour swap too?

Last thing - you say the motors never stop once they're started. Does the controller ever display "Polargraph ready" again, or does it just stay on "Busy..."? Also is that true even if you ask to do a really tiny tiny move?

sn

Ah, that's good news. You can either just turn your arduino upside down, or you can edit the source code to flip the motors.

sn