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Countersink Burrs

What are countersinks burrs used for?

The head of the countersink has a conical shape. The conical shape causes deburring or countersinking into the existing drill hole.

The countersink angle is decisive for the countersink. There are different angles which are intended for different applications. These are for the countersink:

  • 60° for deburring
  • 75° for rivet heads
  • 82° for countersunk screws US standard
  • 90° for countersunk screws
  • 120° for countersinking of sheet metal rivets

The number of cutting edges is normally odd for a smooth run when countersinking. Our countersinks have three cutting edges.

The chip is removed via the flute profile. The shank is available in four different versions: cylindrical shank, Morse taper, bit shank and 3-face shank. A bit shank or 3-surface shank, for example, prevent the tool from slipping in the drill chuck and make them ideal for use in hand drills.


Since our countersinks are made of the tool steels HSS, HSSCo 5 and tungsten carbide, you can use them to cut a wide variety of metals. The countersinks are available with the coatings TiN, TiAlN and our RUnaTEC. Extremely important for countersinks is the countersink angle. The different countersink angles are suitable for different applications.

Flat countersink

Flat countersinks have a cylindrical shape compared to countersinks. Countersinks are used to produce countersinks for cylinder head screws, hexagon head screws and nuts.

At its tip there is a fixed guide which is inserted into the pre-drilled hole. This ensures a stable guidance of the drilling machine and precise working.

The cutting edges cut the material and make space for the head of the screw. Cylinder head screws and hexagon head screws are flush with the surface of the workpiece.

Flat countersinks are available in two versions, for through hole and thread core hole. The difference lies in the two workpieces which are connected with a screw.

With the through hole, there is a thread only in the second material. With the thread core hole, both materials have a thread.

The diameter of the fixed guide for the through hole is larger than for the thread core hole. Thus, for a through hole for thread M12 (fine grade), the diameter is 13.0 mm. For the thread core hole, the diameter of the fixed guide for the M12 thread is 10.2 mm.