Tungsten Carbide Brad Point Drill Bit Ⅲ

In last part we know that the tungsten carbide brad point drill bits cut a clean hole by firstly cutting the hole periphery with outlining spurs instead of a straight chisel to avoid pulling off the wood fiber. This part we will explain the two basic types of brad point drill bit.

There are basically two types of tungsten carbide brad point designs we use. One works best in hardwoods and the other works best in softwoods. Tungsten carbide brad point drills that are specifically designed for softwood produce too much heat and are hard to push in hardwoods. Although brad point drills specifically designed to cut hardwood will cut softwood, the aggressive cutting edges have a tendency to lift the weak grains of the softwood resulting in a ragged edge around the opening of the hole. 

The difference between the two types of points is in the design of the outlining spurs. The brad point drills that work best in softwood have rounded spurs, which help to hold the grains of the wood down while sheering them off. There is a certain amount of rubbing that occurs between the outlining spur and the wood before it is cut. The outlining spurs on brad point drills for hardwood come to a sharp point and simply cut the stronger grains off clean. No rubbing occurs and therefore no unnecessary heat is produced by the cutting action.

(To be continued. This article is divided into 5 parts, and this is part 3. For part 2 please refer to http://news.chinatungsten.com/en/tungsten-information/80397-ti10361; for part 4 please  refer to http://news.chinatungsten.com/en/tungsten-information/80399-ti-10363)

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