Tool for sharpening drills. How to sharpen a drill?

Working with screwdrivers and drills, many people have the question "How to sharpen a drill for metal?" And the answer to it, unfortunately, very few people know. Most often, blunt drills are replaced with new ones. But the fact that the drill is blunted is not the reason to throw it away.

What kind of grinding device can be used in domestic conditions?

In everyday life the most common are spiral drills. They allow you to drill both different metals and wood. Intruding into a metal or other material, the cutting edge of such a device pulls the chips outward on its surface. When drilling soft materials, the chips look like a folded tape, and when a drill penetrates into a solid material, it is free-flowing.

When drilling, the hole receives a conical shape. This is due to the rotation of the cutting edges along the conical path. In this case, the lower edges should be only at the very end of the spiral drill, and on the conical - there should be no protruding elements. All this allows you to remove the shavings more efficiently, due to the appearance of the "back corner". For optimal drilling, it must be calculated correctly. If the sharpening   The angle is 5-10 degrees.

Consider how the sharpening of the drill for metal is performed.

To sharpen drills with an abrasive bar is tedious and long. It is much more convenient to use a grinder or other similar device. For grinding drills, you can make an electric grindstone with an engine up to 300 W and a shaft rotation speed of up to 1500 rpm. In this case, it is necessary to assemble the platform for the motor and find the parts for installing the abrasive wheel.

When sharpening a spiral drill, the angle between the cutting edges for drilling different materials must be different. For drilling bronze, brass, aluminum - 115 (± 5) degrees, steel - 135 (± 5), for drilling soft materials, such as plastic or wood - 95 (± 5) degrees. In shops, in most cases, drills have a universal angle between the cutting edges (120 degrees). Whichever grinding device you use, it is necessary that its tip coincides with the axis, and the edges have the same length.

After forming the edges, you need to process their back surface, sharpen them in the form of a cone. You can use a washer to control this grinding element. Its diameter should be less than the diameter of the drill by 33%. Then, grinding the metal with an increase of 0.2 mm clearance between the drill and the washer on each millimeter of the arc, form the rear corner.

Forming the edges and the rear corner must be done carefully, so as not to damage the cutting surface of the device. For grinding, it is recommended to use a part of the abrasive wheel, which is closest to the end.

In addition to the cutting edges, a jumper actively participates in the drilling process - an edge between the rear surfaces. She kneads and pushes the material. To facilitate drilling, its length is reduced, but if it is removed completely, the drill will quickly break down. This edge should be reduced to 0.5-1.5 mm (depending on the diameter of the drill). If the drill is sharpened less than 4 mm in diameter, the jumper should not be reduced at all.

Sharpening a drill for metal is not an easy task, but it is quite feasible at home. The device for sharpening drills can be bought or manufactured with your own hands, which is much more economical and much more interesting.