Because of the First World War, Wegener's book went unnoticed outside Germany. In 1922, however, a third (revised) edition was translated into English, French, Russian, Spanish, and Swedish, pushing Wegener's theory of continental drift to the forefront of debate in the Earth sciences.
A drilling machine, called a drill press, is used to cut holes into or through metal, wood, or other materials (Figure 4-1). Drilling machines use a drilling tool that has cutting edges at its point.
A typical drill press often has an RPM limitation of between 2000-3600 RPM. If the chart above specifies a higher RPM than your machine is capable of, it should not cause a problem to run at a lower RPM. For instance, many people drill 1/16â³ holes at less than 10,000 RPM with no problems.The process of drilling holes in metal or similar materials without coolant is possible but not suggested.In most metals, the RPM rate can be decreased to 25% of what is shown above.DEPTH = 30% of the diameter of the tool plus the thickness of the material). Add in stroke up to product time. Add in stroke back to home time. Add in clamp and unclamp time. Add in any human factors, etc. Add in time for potentially dull tooling, etc. Add in time for less than adequate machine thrust, etc.