Method for producing drill hole in concrete, ceramic etc involves first drilling smooth hole with drilling head aligned coaxial with drilling tool and then through eccentric revolving spindle parallel to itself to produce rear cut section

摘要

First a smooth drill hole is made of the desired diameter with a normal drill and then the drilling head (6) is turned without further advance to produce a rear cut section (2). In the initial step the drilling head is aligned coaxial with the drilling tool and in the second step the revolving movement of the drilling head without changing the angular position of the head is generated through revolving movement of the drilling spindle (5) parallel to itself. Independent claim describes drilling tool with spindle mounted rotatable in eccentric assembly (10) whose outer diameter is slightly less than the diameter of the drill hole. When the spindle and eccentric assembly are mounted in the drill hole the spindle by rotating the eccentric is movable on a revolving path eccentric with the drill hole parallel to itself.