how to sharpen diamond core drill bit

1. Before grinding the bit, the main cutting edge of the bit and the grinding wheel face should be prevented from being on the same level, that is to say, the whole edge should be ground when the cutting edge touches the grinding wheel face. This is the first step of the relative position of the bit and the grinding wheel.
2.This Angle is the front Angle of the bit. If the Angle is wrong, it will directly affect the size of the top Angle of the bit, the shape of the main cutting edge and the bevel Angle of the transverse edge. Here refers to the position relationship between the shaft line of the drill bit and the surface of the grinding wheel. Take 60°, and this Angle is generally more accurate. Here we should pay attention to the relative horizontal position and Angle position before the bit grinding edge, both should be taken into account, do not ignore the Angle in order to straighten out the edge, or ignore the edge in order to straighten out the Angle.
3.After the cutting edge touches the grinding wheel, grind from the main cutting edge to the back, that is, start from the cutting edge of the bit to contact the grinding wheel, and then slowly grind down the entire back cutting surface. When the drill cuts in, it can touch the grinding wheel gently, grind the edge of a small amount first, and pay attention to observe the uniformity of the spark, adjust the pressure on the hand in time, and pay attention to the cooling of the drill, not to let it burn, resulting in discoloration of the cutting edge, and annealing to the cutting edge. When the cutting edge temperature is found to be high, the drill should be cooled in time.
4.This is a standard bit grinding motion where the main cutting edge swings up and down on the grinding wheel. This means that the hand holding the front of the bit evenly swings the bit up and down on the grinding wheel. The hand holding the handle can not swing, but also prevent the rear handle from warping up, that is, the tail of the drill can not be warped above the horizontal center line of the grinding wheel, otherwise it will make the cutting edge dull, unable to cut. This is the most critical step, and how well the drill grinds has a lot to do with it. When the grinding is almost finished, it is necessary to start from the edge and gently rub the back corner again to make the back of the edge more smooth.
5.After grinding one edge, grind the other edge. It must be ensured that the edge is in the middle of the drill axis, and the edge of both sides should be symmetrical. Experienced master will look at the symmetry of the drill point under the light, slowly grinding. The rear Angle of the bit cutting edge is generally 10°-14°, the rear Angle is large, the cutting edge is too thin, the vibration is severe when drilling, the hole is trilateral or pentagon, the chip is needle-like; The rear Angle is small, the axial force is very large when drilling, it is not easy to cut in, the cutting force is increased, the temperature rises, the bit fever is serious, even can not drill. The rear Angle is suitable for grinding, the tip is in the center, and the two edges are symmetrical. When drilling, the drill bit can remove chips lightly, without vibration, and the aperture will not expand.
6.After grinding the two edges, pay attention to grinding the tip of the bit with a larger diameter.After grinding the two edges of the bit, there will be a plane at the tip of the two edges, which affects the center positioning of the bit. It is necessary to reverse the Angle behind the edge and sharpen the plane of the tip of the edge as small as possible. The way to do this is to stand the drill bit up, align it with the corner of the grinding wheel, at the root behind the blade, and pour a small slot into the tip of the blade. This is also an important point of the bit centering and cutting light. Note that when trimming the edge chamfering, do not grind to the main cutting edge, which will make the front Angle of the main cutting edge larger, directly affect the drilling.
There is no certain formula for grinding drill bits. It is necessary to accumulate experience in actual operation, explore through comparison, observation, trial and error, and add a certain human intuition to grind drill bits better.