Calibration question

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

anyway to adjust motion?

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.

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interesting way to have that programmed. no way to correct the grid?

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.

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its not a giant issue. just tickles my ocd

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Fascinating Will. I didn’t know that (but then, there’s a lot I don’t know…) :slight_smile:

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I describe the math behind it over here: Cannot Calibrate Z Axis


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

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Just change to inches, then you won’t notice because the numbers are so small to begin with. :smiley:

True enough. I find it easier to adjust and edit the code if its metric though

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