Drill grinders, also known as the drill grinding machines, are a device used to grind large drill bits that ranges from 3 to 75 millimeters. Drill grinding machines can also be used to grind end mills, taps, chamfering cutters, and the outer part of workpieces. High precision drill grinders or high precision drill grinding machines are especially known for their superior precision and convenient operation.
Some of the features of drill grinding machines include:
1. Drilling grinding machines are able to grind drill bits up to 3 to 32 millimeters, with specific models capable of drilling drill bit size above 76 millimeters. They can also hierarchical drill bits, NC drill bits, screw taps, chamfering cutters, end faces of end mills, round bars, etc.
2. When grinding different materials, the motor of the drill grinding machine can be conveniently rotated to restore the grinding upon grinding each material. Such simple mechanism can ensure safety and reduce the time for wheel replacement
3. Drill grinding machines can be coupled with 6-jaw chuck, which allows grinding operations to be completed in a single clamping, enabling simple, accurate and efficient grinding.
4. Unlike the other more complicated machine tools, drill grinding machines are known for the ease-of-use characteristics. You do not require highly skilled workers to operate one of these machines.
To understand how drill grinders work, we need to have a basic understanding of each cutting edge of a drill bit. A drill bit can typically come with two to three cutting edges. In this case, we’ll use a twist drill bit as an example:
● The Main Cutting Edge: The main cutting edges are the two longest edges meant for cutting into material. As the main component of a drill bit, the main cutting edges are often the first to be grinded. They are positioned at an angle of about 118 degrees to one another.
● The Secondary Cutting Edge: The secondary cutting edge is the outermost edge of a drill bits, and are not always present in all twist drill bits. It is mainly responsible for making sure that the drill bit is able to make a clean hole.
● The Chisel Cutting Edge: This is the edge that is placed on the material in a twisting motion. It allows the drill bit to drift on a smooth surface, which is why when drilling into metal, pre-drilling or at least center punch is required before actually initiating the drilling.
● The Cutting Angles: In most cases, a drill bit with relatively sharper cutting angle is always better than that of a blunt one. For general purposes, it is not mandatory that the point angle is at 118 degrees.
Now we can start addressing how to go about using a drill grinding machine to grind your drill bits. First and foremost, it is advisable that you begin with a fairly large drill bit. Hold the drill bit in your right and have it position on your left index finger. Have the drill bit pressed against your index finger with your left thumb. Now stand on the left side of the drill grinding machine and place your left index finger on the tray of the grinding machine so that you can place the drill bit on the machine at ease.
Next, things may get a little more complicated here on out as two movements need to be combined. You place the drill bit with the left main cutting edge facing the moving drill grinding machine wheel, gently bring down the rear part with your right hand immediately, and raise the front part with your left, and then turn the drill bit clockwise about one-eighth of a rotation at the same time.
After every one-eighth of rotation, remove the drill bit and see if you are holding the drill bit correctly. If too much pressure is applied on the drill bit or you are holding the drill bit too long against the drill grinding machine wheel, the drill bit can overheat. You have to cool it with water if it glows or gets too hot. Shift to the second main cutting edge by turning the drill bit and continue just as you did with the first one if the main cutting edge reveals a smooth edge. All you have to ascertain now is that the drill bit is balanced, and both of the main cutting edges are of the same length.
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