Improvements to electric drills for masonry

The electric drill most commonly used to drill holes into masonry is the "hammer drill". In this type of drill the bit has both a turning and a back-and-forth hammering motion. One danger in using a powerful drill of this sort is that when the bit becomes stuck the drill is powerful enough to turn itself around the bit. If the operator keeps hold of the drill, he may be thrown off balance. I find that hammer drills do not make holes of a precise diameter.

Unlike drills, electric impact wrenches and impact drivers are capable of exerting very short strong impacts that turn the shaft of the tool. Impact drivers turn like drill until the shaft encounters a large resistance and then they begin to twist the bit by a series of short impacts.. These tools are easier to control than a drill exerting a large torque continuously. It would be worth investigating whether a masonry drill could be invented that used an impact action with a very short stroke, both for turning and hammering.

A simple experiment (and perhaps a good student project) would be to investigate how well an electric impact wrench or drill driver functions as a masonry drill. I have tried a Ryobi brand impact driver and a 1/4" diameter masonry bit. To use a drill bit in the tool, it is necessary to buy a "speed chuck" such as Amazon.com. The impact driver did well in drilling through masonry joints and the sides of concrete block. It was very slow in drilling into solid concrete, but it did as well as my Bosch hammer drill and made a more precise hole. One project would be to try this experiment with a larger bit and a more powerfull impact driver such as an electric automotive impact wrench.

A more elaborate project would be to fabricate a tool that could exert both turning impacts and back-and-forth impacts. This would imitate the hammer drill but use much shorter and more powerful strokes.