Thanks for all your help guys, I'm learning all the time.

I tweaked the axis stepping the other day to improve it a bit, making dimensions a bit more accurate. Upon machining a circle though, I have noticed it suffers at 3, 6, 9 and 12 o'clock, giving flat spots. Can I assume this could be a typical fault of the stepper motors or the board quality? Just a question really, trying to learn about this thing.