ava faasimine: koonilise süvendi töötlemine eritööriista – koonilise süvisti abil (vt süvistus, koonussüvisti; vrd silindersüvistus, otssüvistus), beveling or tapering the work material around the periphery of a hole creating a concentric surface at an angle less than 90 degrees with the centerline of the hole for the purpose of chamfering holes or recessing screw and rivet heads (see: countersinking, counterboring and spotfacing; countersink; compare: counterboring, spotfacing)