Patent attributes
A drill having a web which is provided by a central portion of a cylindrical main body of the drill and which includes a back-tapered portion and a constant-thickness portion. The cylindrical main body has a large diameter portion and a small diameter portion contiguous to the large diameter portion, such that a step is provided between the large and small diameter portions. The large diameter portion provided by the axially distal end portion of the cylindrical main body has an axial length which is larger than an axial length of the back tapered portion of the web provided by the axially distal end portion of the web, such that a boundary between the back-tapered portion and the constant-thickness portion of the web is located in the large diameter portion of the cylindrical main body.
