►Twist drill is a kind of common drilling tool, the structure is simple, but, it is not an easy thing to make a real good grinding. The key is to master grinding methods and techniques. The problem will be solved if you master methods.Chang sha langfeng  introduce manual grinding techniques of twist drill.
Apex angle of twist drill is 118 ° in general, and it also can be regarded as 120 ° Sharpening drill main several skills are summarized as follows:
1,Making the edge be equal with the grinding wheel surface.
Before grinding drill bit to the main cutting edge and grinding wheel surface is placed in a horizontal plane, that is to say, guarantee the edge grinding wheel surface contact the whole blade to grind. This is the first step, drilling and grinding wheel relative position location set to the grinding wheel surface by slowly again.
2, bit axis with the grinding wheel surface inclined angle 60 °
This angle is an angle of drill bit, this time in the right angle, it will directly affect the size of the bit apex angle and the shape of the main cutting edge and chisel edge angle. Here refers to the axis of the bit line and the location of the relationship between grinding wheel surface, taking 60 ° will be good, you can see this angle is compared commonly . To note here before the drill sharpening level and the relative angle position, both to overall consideration, don’t ignore to get the straight edge setting the ° , or to set the angle and ignoring the straight edge.
3, grinding from behind the back edge .
After contact edge grinding wheel, grinding from behind the main cutting edge toward also is from the bit edge started contact grinding wheel, and then along the entire blade surface after grinding down slowly. Bit can contact wheel gently, when cut to a small amount of grinding, uniformity and watch the sparks, adjust size hand pressure, also note that bit of cooling cannot be let the ground fire, be caused discoloration on the edge, and annealing on the edge. Find parts at high temperature in a timely manner will be bit cooling.

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