Some old favorites

I'm starting over with learning how to use this after having it stored away for so long. It took some time last night just to figure out how to program a spiral in the Arduino language. I know I've drawn this before but I wanted to see with the new piece of fish line how consistently it would draw. The waves you can see in the pattern are caused by two things I think. As the string piles up on the bobbins it causes it to move a different distance with each step. The bobbins are not perfectly aligned with the center of the motor since they are just glued on with epoxy and I think that accounts for a lot of the waves as well.
I have a variable in the program for how long it pauses between steps of the motors. If it tries to move too fast it looses steps. The fastest it can move is about 10 milliseconds between steps. For this picture I had it delaying 30 milliseconds. I had it increasing the radius of the spiral by 5 motor steps for each time around.
Now I want to try a rectangular pattern and see how consistent it is.

blew the dust off after a long rest

I finally got this out of storage yesterday. This was the last thing I had been working on in April 2014.