A manually-powered, hand-held, surgical device intended to be used to remove circular sections of the skull vault (calvarium) to provide access to the interior for diagnosis (e.g., the insertion of a neuroscope), or treatments [e.g., to alleviate intracranial pressure (ICP)], or for the removal of a bone flap for brain surgery. It is typically a drill brace or a housing containing bevelled and/or straight teethed gears rotated via a side handle, and a Jacobs chuck or gripping collet to attach an exchangeable rotating endpiece (e.g., a cranial drill, bur, trephine or perforator). This is a single-use device.