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 NCAA College Jerseys , 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, 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 Wholesale Authentic College Jerseys , 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 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, metal Wholesale College Jerseys Free Shipping , plastic, and most other materials, 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 Wholesale College Jerseys From China , 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, 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 Wholesale College Jerseys China , they are not the best tool for routinely drilling deep holes, 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.

Total Views: 163Word Count: 495See All articles From Author
What's happening to the personal touch on the World Wide Web?

The headlong speed with which we rush through the vast information superhighway is leaving human interaction in the cyber dust. How many times have you searched through a website to find a phone number only to discover that one doesn't exist? You'll communicate through e-mail only and if you can't fully explain your issue by written word--too bad! And try using email to try and figure out a technical support issue. It's frightening to see how many companies, of all sizes, are creating policy to use the World Wide Web to hide.

Make no mistake about it Wholesale College Jerseys , the Internet is the most powerful medium we'll see but it's not a place to play hide and seek with visitors. If you own a website, publish a number and man your phones. Answer quickly and use proficient, accommodating customer service specialists. And please don't preach to us about the cost of such a venture. The World Wide Web is creating more millionaires than at any other time in our country's history. Give some of your new found profits back. Be a faithful servant to your customer. Make the Internet all it should be and you will be rewarded beyond compare.

Brian Grinonneau is the general manager of McMann and Tate Advertising, an agency that works exclusively with the small business owner to help them stand out in an increasingly crowded marketplace where much of the advertising and products look the same. Today in various organizations, excel spreadsheets are widely used to maintain large number of contacts details with different attributes such as Name Wholesale Authentic NCAA Jerseys , Phone Numbers, Image, Business Address, House Address, Email Wholesale NCAA Jerseys Free Shipping , Website etc. But some time user find out ways to convert excel file contacts into vCard file format so that vCard file can be import in latest devices, email applications, social networking websites etc.