It’s a regular Sharpie, so not a fine point. I should have thrown a ruler in there for scale. It’s making a line about 1mm wide, so the ripples are fairly noticeable. I took another picture with a ruler and uploaded it.
I’m on a Mac, so my (native) options are limited. I’m currently using jscut, which seems to be working nicely. I had the same thought that maybe it was generating gcode that had ripples in it, but jscut allows me to preview the output. I didn’t trust that either, so I downloaded another app called CAMotics (I think) that also previews milling gcode. I’m pretty familiar with this sort of thing from 3D printing, but the milling side of gcode is definitely new to me. I can virtualize Windows and run estlcam as recommended, but I’m pretty sure that jscut is doing an ok job for the time being and the virtualization route is just a few steps more than I’d like to do unless necessary. I’ve uploaded my sample diagonal test code (which I stopped after it drew the first line). As far as I can tell, this gcode contains straight lines, not ripples, so it has to be the machine not the code.