Drilling And Tapping New Thread In The Hole
Drill out the old threads using the correct diameter drill bit. Blow the hole clean.
Tap the new thread using the correct tap.
NOTE:
The thread taps referred to in the text are specially made for use with the HELI-COIL system.
Use methylated spirit or similar to lubricate the threading operation in aluminum. Thread longer threads in stages, backing out the tap and blowing the tap and the hole clean in between.
Thread the hole to the proper depth (or through if it is to be threaded throughout).
C: drill depth.
D: cutting phase.