A concise history of the rotary hammer drills
Perhaps the most significant Gap between human beings and the rest of the animal world is our capacity to make and use tools. Tools have allowed us to perform tasks which would be hard or impossible to execute otherwise. The drill is the perfect illustration of this. Without a drilling apparatus we would be hard-pressed creating a hole in a material like wood, let alone tougher materials like steel or concrete, not that steel and concrete would likely exist without using different tools anyway, but that is a tangent I will ignore. If We follow the history of this drill back in time we come to the early Egyptians and Harappans, who used a device known as a bow drill, which even more commonly used for making fire, was also utilized in basic woodworking tasks. It was also used by the ancients’ equivalent of the modern dentist; the notion of which I’m sure would raise the heart rate of anybody with a phobia about dental treatment. The components of the device are the bearing block, the spindle, the fireboard and the bow. The string of the bow is wrapped around the spindle, which is held in place at one end from the bearing block and in the drilling end by the fireboard. Leverage is afforded the consumer of the device by the string attached to the bow.
Another Simple device that has been used for centuries is the bohrhammer drill. The components of the device are the drill shaft, a heavy flywheel, a narrow piece of board with a hole in the center, and a string. The flywheel is connected to the base of the shaft and the part of plank is placed over the surface of the shaft by way of the hole. The length of cord is put through a hole at the surface of the shaft and can be attached to either end of the plank. There is a hole in the end of the shaft where the pieces are placed. The board is then held in place while the shaft is rotated until the board has lifted to close the surface of the shaft and the cable is tightly wrapped round the shaft. The tip of the shaft is placed on the material that is to be drilled and downward pressure is put on the board. The shaft spins quickly and once the board reaches the base of the shaft it is permitted to rebound causing the cord to once more wind around the shaft, and the drilling can re-commence.
A More comfortable device is that the brace and bit, which is a drill with a u-shaped grip. The user places pressure on the surface of the drill with one hand and can provide rotational motion through the u-shaped grip with another hand. The u-shaped grip could be thought of as a sort of crankshaft that provides increased torque compared to other hand drills, but with a slower rate of rotation. Another instrument from the not too distant past is that the flip side drill that looks like an eggbeater, and has a handle to grip with one hand on one side, and a rotational device with a handle on the opposite side, which offers the drilling momentum.