I'm programming a pocket that looks sort of like a rats maze, with one island in the middle made up of a bunch of interconnecting "walls" in this maze.

The problem I'm having is that Gibbs seem to ignore this island and machines out the entire pocket. This was with a larger endmill that was almost the width of the "hallway" between "walls", (ie: hallway is .48", so endmill is .375").

But when I changed the endmill to 1/8", everything comes out fine.

I noticed a similar problem yesterday on another part where gibbs ignored one one of the islands in a pocket. I didn't try changing the tool diameter there, but it was a larger tool roughing out the pocket. I ended up working around that problem by drawing a polygon around the island and made the polygon an island in the pocket, then contoured out the actual island.

Has anyone else experience this problem? Any idea what Gibbs is doing, or how to avoid this problem in the future?

Thanks.