Pilot Hole
First, drill the hole in wood or plastic to locate or guide a screw and expand the size according to the tap. Without a pilot hole, the screw may get too tight and either broke the material or snap the screw completely
![Countersink Chamfer Tool]()
Countersink
Install the chamfer drill on the bench drill. If you need to chamfer a 16mm hole, you can choose a 15-20mm chamfering device. Add water or cutting oil to cool when chamfering.
Finally, screw on until flush with the horizontal. This bit should use the bench drill, it is easy to shake and it will affect the chamfering effect if you use the hand drill.
![Countersink Chamfer Tool]()
