My first test was a hand written G code file. But the same "Test Pattern" used for testing a computer printer for aspect ratio accuracy, would be a good test for your machine as well: Draw a perfect square in your vector graphics based software, or CAD program. Next, draw diagonal lines from corner, to corner of the square. (The point where these lines intersect should be the exact center of the square). Using the exact center of the square as the reference point, draw a perfect circle within the square, with it's outer edges touching the lines of the square (this should occur at the exact midway point of the walls of the square between it's corners). Save the graphic, and output to your CAM program to generate the g code file. Do a test cut on your machine, and measure the results. They should match exactly, the measurements used in drawing the graphic. If not, the results should give you a "starting point" from which you could determine any fine tune adjustments needed to correct any inaccuracies. Hope this helps.