Full bore
As a full-bore the earliest traditional techniques for drilling called into solid material. The material is not removed directly from the tool as with modern drills , but with sand as an abrasive between the workpiece and the tool. All materials known at the time, from wood to granite, could be processed.
The basic principle is to set a cylindrical drilling tool made of wood, copper or bone in rotation on a workpiece and to grind a hole in the workpiece by adding dry, sharp-edged sand (preferably quartz sand) . The removal consists of two components. On the one hand, the grains of sand get stuck in the drilling tool and have a grinding effect, on the other hand, the grains roll over the surface and break out fragments. Furthermore, the rolling grains in particular facilitate the rotation of the tool.
The rotary movement of the drill was usually accomplished using a fiddle bow, while the necessary contact pressure and guidance of the drill was carried out using a beam or board that was placed on the face at the upper end of the drill.
The first drills were the so-called whorl drills around 40,000 BC. They consisted of little more than a stick rotated between the palms of the hands by moving the hands together. Only before about 4000 BC BC, people stretched a tendon, once wound around the drill, between the ends of an elastic branch and thus discovered the fiddle drill . The first use of a mechanical drill guide was probably around the same time, as increased speed and force made it difficult to control the drill with bare hands.
See also
Hollow core drill , fire drilling