I have been programming helical cut outs lately with great success. Just thought I would share for those that dont know how. Example: I want to mill a round out of a square. Lets say 2" round, first Draw 2 times 2" circle one at 0 and one lets say 1" deep. I just draw the one and duplicate and translate 1 to 1" deep. Then I put a point on the top circle, then click that point and duplicate and translate how ever deep u want the helics I will use .050. So that will make 20. now click line and top point connect, then line and bottom point connect. they should all connect. you can click it all and hit ctrl T if you want the direction to change.Noe click it all duplicate and translate 19 times at -.050 . Then I click the 1 circle up from the bottom and the bottom circle and the bottom point and connect, then click bottom point hit ctrl +d, {so your duplicating the point} with ctrl still pushed in I click the last circle bottom yellow and then hit connect. The reason for that is then my last pass goes all the way around at 1' deep.
Here it the sample file: