Hi Rich:
There should generally be no problem with a polyline, the problem comes in when a program modifies any element of the polyline by adding a "BULGE" factor tag to it to indicate that line is a bulged polyline entity.
As you guys have seen, the errors generally come into being when either entities cross over each other, ( mainly arc's, Mach3 fixed lines automatically) , OR when a recess in a profile is attempted to be profile by the tool radius distance. By this I mean the first step when generating a toolpath is to offset the main profile by the tool radius amount. This offset profile is used for the computation of the path itself. The module I use doesnt always generate a perfect offset. This is specially true of deep recesses. The result is the message "Sorry, Self intersecting profile found.". When this occurs a smaller tool radius will often work, or larger radisu in some cases. This is due to a breakdown in the 3d solid manipulation. I may find a solution at some point, but reducing the pockets depth may help as well. In the end using a lower radisu tool may be best for the cut in any cae, but Ill leave those details till the end.
Thx
Art