3-Axis Calibration

I made this to check whether the X, Y & Z axes on my printer are set-up correctly.

I have made this part with a notch at 50mm on all axes and and an overall length on all axes of 100mm. I figured this would allow me to see if any inaccuracy got worse as the travel increased, i.e, is the %age error at 50mm the same as at 100mm.

I designed it with radii at the edges in a bid to remove any edge bulges from affecting the measurement. I am not sure how successful that was, but it shouldn't affe