Hi,
Last time I calibrated my $100/$101 values, I went blue in the face trying to figure out correct average values that would work across the work area and for various dimensions of the cut, and found out the hard way that it is quite difficult to find a “perfect” pair of values (I should have read the multiple posts from @RichCournoyer on this, stating that the effort is pretty much hopeless and one might as well do a test cut and scale the CAD based on the measured results). I ended up leaving the calibration factors alone, and indeed adjusting tolerances here and there while designing.
The inner geek in me has been thinking about correcting the small non-linearities of the movements on the X and Y axis by first mapping them across the work area and then having GRBL compensate for them dynamically. A map of $100/$101 calibration factors depending of x and y position, if you will. Kinda like the basic “bed leveling” function of 3D printers, where a sensor comes and probes the surface across a large 2D area, and Marlin firmware then has this matrix of correction coefficients that it applies to correct the tilting of the surface.
Has anyone entertained a similar idea ? It’s probably not worth the effort (i.e. many people get extremely good precision without resorting to this), but imagine if we had a fully automatic belt stretch compensation/calibration procedure based on one test cut, wouldn’t that be nice ?
Does the Shapeoko use the vanilla GRBL 1.1 source code publicly available ?
Cheers,
Julien