[jsapers]

Hi All,

We are using a home built CNC mill running on Mach4. When we cut circles, we noticed flats on the top and bottom of the holes (see attached pictures). We measured the backlash of our machine and it was not significant. We tried different Gcode generators and got the same result. After that, we cut a square with the corners facing in the X and Y directions. After inspecting the square, we found that the corners pointing in the Y axis directions were flat instead of pointed and the Y axis diagonal is 0.015" shorter than the X axis. It seems to us that for some reason the controller is not directing the machine to travel the full Y distance. Has anyone seen this issue/ know if there is a setting that could fix this?

Thanks,
Josh

[joeavaerage]

Hi,
if its not backlash then it is machine flexure....they have a similar effect.

I've used Mach4 for many years and I expect a circularly interpolated hole to be within 0.02mm (0.0008 in) of round. Even then I would expect that the majority of the 0.02mm
out-of-round, say 0.015mm, would be the flexure of the 1.5mm and 3mm tools that I commonly use.

Craig

[jsapers]

Thsnks for responding! I am reluctant to say it is flexure as we still see the same problem when we lower the feed rate and reduce the force on the tool.