Masonry/concrete drill bits and other tooling:

WIKIPEDIA
Drill bits are cutting tools used to create cylindrical holes. Bits are held in a tool called a drill,which rotates them and provides axial force to create the hole. Specialized bits are alsoavailable for non-cylindrical-shaped holes. This article describes the types of drill bits in terms
of the design of the cutter. The other end of the drill bit, the shank, is described in the drill bit shank article. Drill bits come in standard sizes, described in the drill bit sizes article.A comprehensive drill and tap size chart lists metric and imperial sized drills alongside the required screw tap sizes. The term drill can refer to a drilling machine, or can refer to a drill bitfor use in a drilling machine. In this article, for clarity, drill bit or bit is used throughout torefer to a bit for use in a drilling machine, and drill refers always to a drilling machine.
Contents: 1 Metal drills, 1.1 Twist drill, 1.2 Gun drill, 1.3 Center drill and spotting drill,1.3.1 Use in making holes for lathe centers, 1.3.2 Use in spotting hole centers, 1.4 Core drill,1.5 Left-hand bit, 1.5.1 Screw extractor, 1.6 Countersink bit, 1.7 Index able drill, 1.8 Spade drill, 1.9 Trepan, 1.10 Ejector drill, 2 Wood drills, 2.1 Lip and spur drill,2.2 Spade bit,2.3 Forstner bit, 2.4 Step bit, 2.5 Center bit, 2.6 Auger bit, 2.7 Gimlet bit, 2.8 Hinge sinker bit, 2.9 Adjustable wood bit, 3 Other materials, 3.1 Diamond core bit, 3.2 Masonry drill,3.3 Hole saw, 3.4 PCB through-hole drill, 3.5 Installer bit, 4 Well drilling bits, 5 Materialsfor bit construction, 5.1 Steels, 5.2 Exotic materials, 5.3 Coatings, Metal drills
Twist drill: The twist drill bit is the type produced in largest quantity today. It drills holes in metal, plastic, and wood. The twist drill bit was invented by Steven A. Morse[1] of East Bridgewater, Massachusetts in 1861. He received U.S. Patent 38,119 for his invention
on April 7, 1863. The original method of manufacture was to cut two grooves in opposite sidesof a round bar, then to twist the bar to produce the helical flutes. This gave the tool its name. Nowadays, the drill bit is usually made by rotating the bar while moving it past a grinding
wheel to cut the flutes in the same manner as cutting helical gears. Tools recognizable as twist drill bits are currently produced in diameters covering a range from 0.05 mm (0.002") to 100 mm (4"). Lengths up to about 1000 mm (39") are available for use in powered hand tools.
The geometry and sharpening of the cutting edges is crucial to the performance of the bit.
Users often throw away small bits that become blunt, and replace them with new bits, because they are inexpensive and sharpening them well is difficult. For larger bits, special grinding jigsare available. A special tool grinder is available for sharpening or reshaping cutting surfaces on twist drills to optimize the drill for a particular material.Manufacturers can produce special versions of the twist drill bit, varying the geometry and the materials used, to suit particular machinery and particular materials to be cut. Twist drill bits are available in the widest choice of tooling materials. However, even for industrial users,most holes are still drilled with a conventional bit of high speed steel.
The most common twist drill (the one sold in general hardware stores) has a point angle of 118 degrees. This is a suitable angle for a wide array of tasks, and will not cause the uninitiated operator undue stress by wandering or digging in. A more aggressive (sharper) angle,
such as 90 degrees, is suited for very soft plastics and other materials. The bit will generally be self-starting and cut very quickly. A shallower angle, such as 150 degrees, is suited for drilling steels and other tougher materials. This style bit requires a starter hole, but will not bind or suffer premature wear when a proper feed rate is used.
Drills with no point angle are used in situations where a blind, flat-bottomed hole is required. These drills are very sensitive to changes in lip angle, and even a slight change can result in an inappropriately fast cutting drill bit that will suffer premature wear.
Drill bit geometry has several aspects:The spiral, or rate of twist in the drill, controls the rate of chip removal in a drill.
A fast spiral drill is used in high feed rate applications under low spindle speeds,
where removal of a large volume of swarf is required. Low spiral drills are used in cutting applications where high cutting speeds are traditionally used, and where the material has a tendency to gall on the drill or otherwise clog the hole, such as aluminum or copper.
The point angle is determined by the material the drill will be operating in. Harder materials require a larger point angle, and softer materials require a sharper angle.The correct point angle for the hardness of the material controls wandering,
chatter, hole shape, wear rate, and other characteristics. The lip angle determines
the amount of support provided to the cutting edge. A greater lip angle will cause the drill to cut more aggressively under the same amount of point pressure as a drill with a smaller lip angle. Both conditions can cause binding, wear, and eventual catastrophic failure of the tool.
The proper amount of lip clearance is determined by the point angle. A very acute point angle has more web surface area presented to the work at any one time, requiring an aggressive lip angle, where a flat drill is extremely sensitive to small changes in lip angle due to the small surface area supporting the cutting edges.The Mechanic Drills used widely by vendors to further describe the length of the drill itself.
The actual length x diameter must be found and published.The Jobber Drills used widely by vendors to further describe the length of the drill itself.
The actual length x diameter must be found and published.Most drills for consumer use have straight shanks. For heavy duty drilling in industry, drills with tapered shanks are sometimes used.Twist drill bit cutting edges, Twist drill bit with Morse taper shank 11/32" (8 mm) drills - long-series morse,
plain morse, jobber Long series drills are extended length twist drills. They are not the best tool for drilling deep holes, as they require frequent withdrawal to clear the flutes of swarf and prevent drill breakages. Gun drills are the preferred drills for deep hole drilling.
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