How to make a good hole (woodworking drill)
Hit the tree. (At that time, make sure that there is no gap between the wood and the work material.)

Wrong drilling method (woodworking drill)
It is not enough to increase the rotation speed of the electric. The tip of the drill may be seized or chipped. </ span>
Maintain the proper rotation speed of the optimum drill.
In the case of a through hole, at the end, it assists after idling.
Drilling deeper than the groove length (effective length) will lead to damage to the drill, so drill with a drill that has a slight margin beyond the depth of the hole to be drilled. (We do not recommend the effective length of the last minute) </ span>