This checkbox determines whether leads in internal cutouts with corners will attach on the "flats" (sometimes curves), or at Internal Concave Corners.
NOTE If Pierce Centrally On Small Holes is checked and applicable, then the pierce centrally setting will take priority.
 Leadin at Internal Corners |
 Leadin at Internal Corners |
Notice in the above cases how pierce allowance is taken into account, the leadin is positioned so that the pierce allowance does not cross the part, but it can overlap the cut. Pierce Centrally On Small Holes takes a stronger approach in terms of keeping the pierce away from the cut altogether, where it can.
You may also notice that where the lead attached to the corners on the right, that the cut is shortened slightly, effectively using some UnderCut. This is to prevent the kerf of the tool gouging past the corner. The amount of UnderCut is automatically computed for you.
