This type of core drill is no longer in use as modern drill technology allows standard drilling to accomplish the same at a much cheaper cost.
This gives exploration companies the information necessary to begin or abandon mining operations in a particular area.Īn oriented core goniometer, commonly used when analyzing cores for contacts and other structural featuresīefore the start of World War Two, Branner Newsom, a California mining engineer, invented a core drill that could take out large diameter cores up to 16 feet in length for mining shafts. The core samples are recovered and examined by geologists for mineral percentages and stratigraphic contact points. This is the reason that diamond-tipped core drills are commonly used in construction to create holes for pipes, manholes, and other large-diameter penetrations in concrete or stone.Ĭore drills are used frequently in mineral exploration where the coring may be several hundred to several thousand feet in length. Core drills are used for many applications, either where the core needs to be preserved (the drilling apparatus used in obtaining a core sample is often referred to as a corer), or where drilling can be done more rapidly since much less material needs to be removed than with a standard bit. The earliest core drills were those used by the ancient Egyptians, invented in 3000 BC. For drilling masonry, carbide core drills can be used, but diamond is more successful when cutting through rebar.
Core drills are commonly water cooled, and the water also carries away the fine waste as a slurry. Core drills used for concrete and hard rock generally use industrial diamond grit as the abrasive material and may be electrical, pneumatic or hydraulic powered. The material left inside the drill bit is referred to as the core.Ĭore drills used in metal are called annular cutters. A modern core drill is a drill specifically designed to remove a cylinder of material, much like a hole saw.
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