Suggested Procedure
Step 1: Drill a hole with the 9/32" drill.
Step 2: Ream the hole with the 5/16" reamer.
Step 3: Consult the mounting hole drawing and calculate the depth required for the .451/.458" hole to leave .225" minimum length of the 5/16" (.312") diameter hole. Using the special 29/64" pilot drill, drill to the depth calculated above, perhaps leaving a little excess to be removed in step 7.
Step 4: Drill with the 17/32" drill, if necessary, so as to leave approximately 1" of the 29/64" diameter hole length.
Step 5: Tap with the 1/2 - 20 plug tap (tap with tapered lean) as deep as possible without striking the chamfered seating surface that was produced by the pilot drill.
Step 6: Tap to the final depth with the 1/2 - 20
UNF bottoming tap.
Step 7: Examine the seating surface of the mounting hole. If it has been marked by the tapping operation, touch it up with
the pilot drill.