Just a tip... If using Mach3 it is best to avoid G2 /G3 arcs. If that is not possible then create the toolpath with a lead-in with the same radius as the arc for all circular cut-outs. (There is basically a 'never to be fixed' tangential control bug which will rotate the tool whilst lowered into the work - this does not cause problems for thin material but can be a real pain when cutting thicker stuff). Tweakie.
