I have a Zenbot and it is accurate consistently up to .004 for my woodworking projects. If you are experiencing problems, there are many factors that could apply. The machine itself is belt driven, so expect it not to be as accurate as a mill with ballscrews. The spindle motor is not pro quality, since it is a standard roto-zip which will have unusually high runout. If your motor tuning configs are right, and gen configs are right, it is a very stable, and consistent little machine. How much is your machine deviating? If we are talking thousandths, how many. If we are talking in tens of thousandths, then your motor tunings are probably off.