Tooling comp offsets the cutter depending on which direction you are
cutting. There are codes for comp left and comp right and the tool diameter
is set in there somewhere. For example, if you use tooling comp left and
cut a 1" diameter circle clockwise, you will cut a hole in the wood that is
1" plus 2 X the cutter diameter, but the disc cutout would be 1". If you
used the same settings and cut the circle CCW, the hole would be 1"
I don't know anything about WINCNC, I use Bobcad/cam for my CNC mill. I can
draw a part (or import), generate the code, and send it to my mill all from