im making a round knob, i need 2 set screws in the body, when i pu the holes in i can only dim the dist between the holes, when i try to dim from the edge of the part, the dim goes on an angle from the center, also the holes dont go straight in. i tried using a plane on the outside and from the inside, hole wizzard ignores the plane and goes to the surface. what am i doing wrong here?