60° Countersinks are used for centering.
82° Countersinks are used for countersinking flathead screws..1/4,COUNTERSINK 100DEG SGL FLUTE - 3600E 90° Countersinks are used for chamfering and deburring. Single Flute Countersinks should be used when multi-flute countersinks chatter or the hole is too small for a multi-flute countersink to enter.