Using a negative number in “Stock to Leave” absolutely works to make an oversized slot. Here’s some test cards, plus I used it on the computer table attachment to the crossfire that I modified. I had designed it for 16 gauge and decided to move up to 12 gauge for the arm. Used it to increase the size of the slots. They were a little long, but since I was welding them anyway…
Smallest slot here is a 1/16". I had trouble programming the cut in Fusion since it was such a small slot. Had to make clearance 0, square corners, no lead-in. Plus it’s the first pierce. Didn’t really care since I just wanted to know the width here. This is in 12 gauge, increase in program is -.010", which makes the slot .020" wider (for others reading).
I’ll turn them off once I stop spending half my time figuring out how to use the program. Basically most CAM programs have the same features… they just hide them differently!