The twist drill bit is the type produced in largest quantity today. It comprises a cutting point at the tip of a cylindrical shaft with helical flutes; the flutes act as an Archimedean screw and lift swarf out of the hole.

The twist drill bit was invented by Steven A. Morse of East Bridgewater Wholesale Jonas Jerebko Jersey , Massachusetts in original method of manufacture was to cut two grooves in opposite sides of a round bar, then to twist the bar (giving the tool its name) to produce the helical flutes. 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.


Twist drill bits range in diameter from 0.002 to 3.5 in (0.051 to 88.900 mm)[5] and can be as long as 25.5 in (650 mm).


The geometry and sharpening of the cutting edges is crucial to the performance of the bit. Small bits that become blunt are often discarded because sharpening them correctly is difficult and they are cheap to replace. For larger bits Wholesale Avery Bradley Jersey , special grinding jigs are available. A special tool grinder is available for sharpening or reshaping cutting surfaces on twist drill bits in order to optimize the bit 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 Wholesale Isaiah Thomas Jersey , even for industrial users, most holes are drilled with standard high speed steel bits.



A 5 mm carbide bit displaying shallow point angle.
The most common twist drill bit (sold in general hardware stores) has a point angle of 118 degrees, acceptable for use in wood Wholesale Kyrie Irving Jersey , metal, plastic, and most other materials Cheap Marcus Smart Jersey , although it does not perform as well as using the optimum angle for each material. In most materials it does not tend to wander or dig in.


A more aggressive angle, such as 90 degrees, is suited for very soft plastics and other materials; it would wear rapidly in hard materials. Such a bit is generally self-starting and can cut very quickly. A shallower angle Cheap Marcus Morris Jersey , such as 150 degrees, is suited for drilling steels and other tougher materials. This style of bit requires a starter hole, but does not bind or suffer premature wear so long as a suitable feed rate is used.


Drill bits with no point angle are used in situations where a blind Cheap Terry Rozier Jersey , flat-bottomed hole is required. These bits 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.


Long series drill bits are unusually long twist drill bits. However, they are not the best tool for routinely drilling deep holes Cheap Jaylen Brown Jersey , as they require frequent withdrawal to clear the flutes of swarf and to prevent breakage of the bit. Instead, gun drill bits are preferred for deep hole drilling.

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LG Optimus 3D is the 3DS of Android phones

Posted On : Sep-15-2011 | seen (72) times | Article Word Count : 414 |

The LG Optimus 3D is the rst 3D Smartphone that is officially introduced in India. It runs of Android 2.2 Froyo OS and the processor is the Dual core 1 GHz ARM cortex A9. The LG Optimus 3D is the w 檚 first 3D Smartphone that is officially introduced in India. It runs of Android 2.2 Froyo OS and the processor is the Dual core 1 GHz ARM cortex A9. It features a huge 4.3 inch capacitive touchscreen an