The other day I cut a 42" diameter circle for a table, to my surprise it was 41¾ x 41⅞.
I don’t normally do projects this size, and the .006" per inch was something that never bothered or was noticed by me.
I used the built in calibration wizard at like 12", and it was good enough for smaller projects.
What i did to correct it:
Create a gcode in my Cad software with 2 single lines 46" apart about 1" long. Make sure the tool paths are on the outside of the lines with the smallest bit (1/16" endmill). I only went like 1/16" deep.
Run it
Hook the tape measured and measure it.
Plug it into the following formula:
T/R=EF
EF×CR=NR
distance Traveled divided by distance Requested equals Error Factor
Error Factor times Current motor Revolution equals New motor Revolution
Example:
45.724 / 46 = .994
.994 × .6859 = .68178
The red box is where the motor revolution is, not to be confused with driver resoltion and associated dip switches.
