Question 650General Subjects - Assistant Engineer

The correct answer is A) slightly larger than the web thickness of the larger drill. When drilling holes larger than 1/2 inch, it is a good practice to first drill a pilot hole. The pilot hole should have a diameter slightly larger than the web thickness of the larger drill. This helps to guide the larger drill and prevent it from wandering or binding during the drilling process. The pilot hole provides a starting point and reduces the strain on the larger drill bit, leading to a cleaner, more accurate hole. The other options are incorrect because: B) a pilot hole smaller than the dead center of the chisel edge would not provide adequate guidance; C) a pilot hole too small would not allow the larger drill to cut effectively; and D) a pilot hole equal to half the diameter of the larger drill would be too large and may not provide the necessary support.