three-lipped

- Internal side-cutting tool (boring tool) or spiral-fluted counterbore (three-lipped twist drill) to produce the hole with machining allowance for reaming.

3. Preparation for reaming Detlev Krechlok 1990

Being a three-lipped tool, it is used for expanding holes (preparation) for reaming.

6. Centring, drilling and counterboring or countersinking Dieter Frank 1990

- three-lipped twist drill (spiral countersink) - head counterbore or counterboring tool with pilot

1. Objectives and contents of practical vocational training in the working techniques of “Drilling, Countersinking and Counterboring” 1990