I cut an S pattern to check for backlash in the X axis and the results were perfect in Easel. I haven’t tried generating the gcode in Easel and using UGS to carve, but that should produce an imperfect circle as well if the problem is Easel. The size of the circle doesn’t matter either. I’m not losing steps… They just don’t happen, like they aren’t in the code. The circle was perfect along the Y axis, but had a very slight flat spot at each of the X axis extremes–we’re talking only 1 or 2 tenths of a mm–but it is noticeable. I flashed my Adruino back to the X-Carve GRBL and tried the same cut in Easel. Perfection! This makes me question Easel and how toolpaths are calculated for circles.

Then I tried cutting a circle drawn in Inkscape with Estlcam and UGS. My machine is dialed in and is very accurate on everything (steps per mm are dead on), even arcs and curves–but the perfect circle is like the holy grail… I have had some issues with perfect circles as well. I have found something interesting when I was carving today.

Esti cam cnc arcs circle not working