Interpolate the inscribed circle first. That's very quick and easy and can be run faster than following the outline of the hexagon. You could even use the hole interpolation wizard in G-Wizard Editor:
GWCC: Happily Interpolating Holes with CNC Conversational Programming! « CNCCookbook CNC Blog CNCCookbook CNC Blog
Once you have a hole interpolated with the 1", swap tools and make one roughing pass and then one finish pass. Shouldn't be that much material to remove after the interpolated hole is cut, so maybe you wouldn't even need 2 passes, but let's just be conservative.
Should be pretty easy to write that code.
Best,
BW
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