GRBL for both the old and updated CNC frame. I did use the old DRV8825 for the old CNC. This setup made perfect circles. The updated CNC used GRBl with the TB6600 drivers. I will test my drivers, but I think you might be right about it being mechanical. The reason it might be mechanical is that the old CNC used a solid 40x40 extrusion for the gantry rails instead of two 80x20 extrusions.
Hey Jimmy! Looks like I found out what's causing the misalignment! Not the software, not the steppers, not the direction of cut, not the drivers.. It was the eccentric v-wheels! What's weird was that I needed to loosen them NOT tighten, haha. After I loosened them ALL (including the z-axis) to the point of the wheels being able to spin a bit, I was able to get super concentric circles! Thanks you guys for your help!
This thread literally stopped me tearing my hair out! I had exactly the same problems and had tried everything - everything except loosening the concentric nuts on the x axis!! As soon as I did this it worked... thankyou everyone for contributing!
Thanks Stanley!! You save me! I had this problem and was losing hope. Now, its solved. Thanks for sharing!