Small bit drilling, drilling machine speed is fast or slow?
The two cutting edges should be the same length, and the cutting edge is usually between 8~12 degrees. Do not cut the cutting edge even lower than the back angle, so that the drill can not be drilled. In addition, the drill bit should be slightly sharpened so that the axial resistance of the bit during drilling will be reduced, so that the drill can save a lot of effort when drilling down.
This size is easy to guarantee. A drill bit is to make two cutting edges for the small angle grinding symmetry, if you want to drill the round, can put some small angle grinding, namely some sharp, this bit in drilling, centering is better, the hole wall is relatively light.
The main reason for the large size is the asymmetry of the sides of the drill. Also, do not drill directly with such a large drill. First drill with a small bit, then use a larger bit to expand the hole
