My sizes are out

[routercnc]

The fact you are cutting circles makes me wonder about the I & J moves, settings for those in the controller (if any), and anything associated with going around corners ?

This is a bit of a long shot but does it do the same thing if cutting out 33 mm square holes (ignoring the tool rad in the corners) ?

I just remember something years ago on I & J radius settings (note: this was in Mach3).

Another option: Is there is a setting for "Maintain velocity (and approximate toolpath)" OR "slow down and follow it exactly" - might be a factor ?

Sorry, just some straws to clutch at.