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Goodbye Mallet

Goodbye Mallet

New Tool-less Drill Bit Introduced at BeBoSa 2017
By Michael Findeis

An experienced core drilling operator certainly knows in an instance what the photographer had in mind when taking this picture. To loosen a stuck drill bit from the motor, there is often only one archaic way to do it and it involves a mallet and two 41-millimeter (1.614-inch) wrenches.

During summer 2010, the national associations of Germany, Switzerland, Austria and the Netherlands held a meeting and unanimously agreed that this cannot be the accepted method for modern diamond-drilling technology, especially as more powerful engines are being introduced to the industry.

The commonly-used 1.25-inch unified coarse (UNC) thread is an old U.S. thread taken from the first deep drillings in the mid-twentieth century and had been proven successful in the oil industry. As the thread had been tried and tested, it was applied to the new and upcoming industry of core drilling through drill bits introduced to the market in the late 1960s. This thread design is still in use today.

The initiative of the associations, especially the German association Fachverband Betonbohren und –sägen e.V., was to try and develop a new thread—one that allows for a quick change of core bit. With what was a quite demanding and complex task, the association was directed to the industry’s manufacturers association, the VDMA (Verband Deutscher Maschinen- und Anlagenbau). This association has the majority of diamond tool manufacturers within its membership, and promptly founded a task force to solve the “mallet and wrench” problem and develop a new thread design.

After numerous meetings and a series of tests with many contractors, the task force decided on a system that was presented to the public at the BeBoSa 2017 sawing and drilling trade show, held March 23-25 in Germany. Visitors were given opportunity to learn more about this core drilling development and test the new conical six times polygon profile thread for drill bits at the German association’s exhibit booth. Prior to this event, German association member Michael Findeis of Findeis Betonbohrservice GmbH presented this thread concept to CSDA members during the U.S. association’s March 14-18 Convention & Tech Fair in Puerto Rico.

The advantages of this new thread design are:
• It is easy to loosen the drill bit without using any tools. It provides an ergonomic assembly and disassembly of the drill bit. Both the operator and machine are considered, lowering the risk of injury
• High levels of torque are transferred easily and without vibrations
• It has excellent dynamic properties through a perfect concentricity
• A very short construction with low weight
• Self-centering
• There are no hollows, as they are in the thread, so it is easy to clean
• While drilling horizontal, the drill bit can be laid on the spindle. Then both hands are free and can be used to lock the screw nut

It is hoped that this new system can be offered by all manufacturers in the industry as a standard connection with their motors. Until this happens, contractors can use a six times polygon adapter for their existing machines. For more information, contact the German association at 49-6151 870956-0, or visit

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