Countersinks
Single Flute Countersinks should be used when multi-flute countersinks chatter or the hole is too small for a multi-flute countersink to enter.
60° Countersinks are used for centering.
82° Countersinks are used for countersinking flathead screws.
90° Countersinks are used for chamfering and deburring.
100° Countersinks are used to make screw and rivet holes.