6 Tips To Easily Grind Drill Bits

Fried Dough Twists drill is a commonly used drilling tool with simple structure. Grinding the drill edge is very important for workpiece processing, but it is not easy to grind it properly. The key is to master the methods and techniques of grinding. Once the methods are mastered, coupled with multiple grinding experiences, one can effectively grasp the grinding scale of the drill bit.
The top angle of Fried Dough Twists drill is generally 118 °, which can also be regarded as 120 °. If you can master the following 6 techniques for sharpening drill bits, there is generally no problem.
1. Before grinding the drill bit, the main cutting edge of the drill bit should be placed on a horizontal plane with the grinding wheel surface, which means that when the cutting edge contacts the grinding wheel surface, the entire edge should be ground. This is the * step of the relative position between the drill bit and the grinding wheel. Once the position is set, slowly move it towards the grinding wheel surface.
2. This angle is the tip angle of the drill bit. If the angle is not correct at this time, it will directly affect the size of the drill bit tip angle, the shape of the main cutting edge, and the cross cutting angle. This refers to the positional relationship between the axis of the drill bit and the surface of the grinding wheel, taking 60 ° is sufficient, which is generally more accurate to see. Here, it is important to pay attention to the relative horizontal and angular positions of the drill bit before grinding. Both should be balanced and taken into account. Do not neglect the proper angle or angle in order to level the cutting edge.
3. After the cutting edge contacts the grinding wheel, it should be ground backwards from the main cutting edge, that is, starting from the cutting edge of the drill bit to contact the grinding wheel first, and then slowly grinding downwards along the entire back cutting surface. When the drill bit is cut in, it can gently touch the grinding wheel, first perform a small amount of grinding, and pay attention to the uniformity of the sparks. Adjust the pressure on the hand in a timely manner, and also pay attention to the cooling of the drill bit. Do not let it burn too hard, causing the cutting edge to discolor and eventually anneal. When the temperature of the cutting edge is found to be high, the drill bit should be cooled in a timely manner.
4. This is a standard drill bit grinding action, where the main cutting edge swings up and down on the grinding wheel, meaning that the hand holding the front of the drill bit should evenly swing the drill bit up and down on the grinding wheel surface. But the hand holding the handle cannot swing, and it is necessary to prevent the back handle from tilting upwards, that is, the tail of the drill bit cannot be raised above the horizontal centerline of the grinding wheel, otherwise it will make the cutting edge dull and unable to cut. This is the most crucial step, whether the drill bit is well ground or not is closely related to it. When the grinding is almost done, start from the edge of the blade and gently rub against the back corner to make the back of the blade smoother.
5. After grinding one edge, grind the other edge, ensuring that the edge is in the middle of the drill axis and symmetrical on both sides. Experienced masters will inspect the symmetry of the drill tip under bright light and slowly polish it. The back angle of the cutting edge of the drill bit is generally 10 ° -14 °. If the back angle is too large, the cutting edge is too thin, causing severe vibration during drilling. The hole opening is triangular or pentagonal, and the chips are needle shaped; The back corner is too small, and the axial force during drilling is very high, making it difficult to cut in. The cutting force increases, the temperature rise is high, and the drill bit heats up severely, even making it impossible to drill. The back angle grinding is suitable, with the tip aligned and the two blades symmetrical. During drilling, the drill bit can easily remove debris without vibration, and the aperture will not enlarge.
6. After grinding the two edges, pay attention to grinding the tip of the drill bit for drill bits with larger diameters.
After grinding the two edges of the drill bit, there will be a flat surface at the tips of the two edges, which affects the center positioning of the drill bit. It is necessary to invert the angle behind the edge to make the flat surface of the edge as small as possible. The method is to stand the drill bit upright, align it with the corner of the grinding wheel, and make a small groove at the root behind the blade, facing the tip of the blade. This is also an important point for centering the drill bit and cutting lightly. Be careful not to grind the chamfer of the grinding edge to the main cutting edge, as this will cause the rake angle of the main cutting edge to be too large, directly affecting the drilling.
There is no fixed formula for grinding drill bits, and it is necessary to accumulate experience through practical operation, compare, observe, repeatedly experiment and explore, and add a certain level of human intuition in order to better grind drill bits.