i calibrated my shapeoko xxl as i was about .25 mm out over 600mm. not bad but easy enough to adjust.

However… now the postion readout in carbide motion has odd numbers in the read out. i tell it to move from zero 5mm in x&y and the machine moves perfectly but the reado ut will read 4.997 and 5.001

Unfortunately, the numbers displayed in Motion are a rounding off of the grid numbers to which the machine can move (to envision this, draw up a 1/40th of a mm grid, then scale that grid to match the # of steps / mm which you’ve set Grbl to — those are the positions which the machine can actually move to.

It’s a consequence of a finite number of decimal points — the correction would be to go back to 40 steps / mm and to then map out where things fall and to scale things as needed to make them come out to the correct size.

thanks. i got it calibrated and its within .001 over 6" and .001 over 24" so im happy. just the display wont read even numbers. i probe the z and it leaves the bit at 31mm then i tell it to move up 1mm and it moves ( according to display readout ) 1.001mm. just drives my OCD crazy