Hi Lee,

Something else to check - is the circle round or oval? It looks very much like you have set the X axis up with the wrong data. If the circle is round then the Y axis is also out. You have not said whether the piece is the right height in the Y axis. Apologies - just looked at your post again and you say it is 3mm out all round. As mentioned by Kwackers, some accurate measurement is needed to determine if the error is cumulative. i.e. gets larger the further the axis travels. If this is indeed the case, you will need to double check your leadscrew pitch, stepper steps and steps per mm.

Mike