Abstract: A drill bit is formed of an insertion end part (1) and carrier part (2) containing drilling cutter members (8). The insertion end part (1) and the carrier part (2) are joined together by a threaded connection. The two parts are secured by a radially flexible spring washer (7) for preventing an unintended detachment of the two parts.

Abstract: In drilling a bore in a structural component (3) using a hollow cylindrical core drill bit (4) initially a guide such as a disk (1) or a template (12) is secured to the surface of a structural component (3) for guiding one of the inner or outer circumferential periphery of the core drill bit. At the commencement of the drilling operation, the core drill bit (4) is guided by the disk or template and maintains the bit in a centered position. The guide can be fixed to the surface of the structural component (3) in a known manner, such as by an adhesive or by fastening elements (2, 6) driven directly into the structural component. Generally core drill bits of smaller diameter can be guided by the outer circumferential periphery of the guide (2) or by the inside circumferential periphery of the template (12).

Abstract: A hollow drill (1) is made up of a tubular carrier part (2), a cutter part (3) and an intermediate part (4) extending between the carrier part (2) and cutter part (3). The intermediate part (4) is rigidly fixed to the cutter part (3). The carrier part (2) and the intermediate part (4) have axially extending extensions (11, 12) which telescope one into the other with solder (8) located between and removably connecting the extensions (11, 12) together.