very basic cad cam software

[JAZZCNC]

That is why I suggested making the hole diameter slightly bigger and routing it out - this has worked for me for years!!! Of course if you have a drill cycle option that works fine as well. G.

So what if there are say 166 holes.? Do you change ever piece of geometry.? how longs that going to take.! (Answer In this case would actually be to tell Cam tool is 2.99mm but hole will still be wrong size)
What if the holes are for dowl pins and need to be exactly 3mm.? In this case a 3mm endmill won't work so again more time wasted swapping out endmills.

Maybe I'm being a bit Pedantic here but Better to get into a habbit of using the easiest and less disruptive option which in this case would have been a Peck drill than changing geometry or using fudges like under sizing tools in Cam.