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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 New Nike NBA 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, to suit particular machinery and particular materials to be cut. Twist drill bits are available in the widest choice of tooling materials. However Wholesale New NBA Jerseys , 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, plastic, and most other materials Wholesale Nike NBA Jerseys , 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, 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 Wholesale NBA Jerseys Online , 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, 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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Family Bonding Activities for Thanksgiving. Family Articles | November 6, 2002
... to reprint and change ... are three main themes for ... ... the harvest Wholesale NBA Jerseys Free Shipping , and family. We can lose track of these things when we're busy ... for c


Permissino to reprint and change title.
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There are three main themes for Thanksgiving: gratitude, the harvest, and family. We can lose track of these things when we're busy preparing for company and big meals, and Christmas shopping, and the kids are out of school too! Here are some ways you and the family can share some time recapturing the meaning of Thanksgiving, or even start some new traditions.



Let each member of the family make a list of things they're grateful for. Read the lists before the meal and save them for memories in years to come.


Start a "thanks" journal you'll keep all year.
Instead of writing down problems and concerns Wholesale NBA Jerseys From China , write down the things you're grateful for.


Think harvest! Make a trip to your local Farmers Market or Produce Row to take photos, have fun, and support the people who feed us all!


Spend the long weekend on family projects such as making a Family Tree. For help, visit ancestry, or check out the Family Tree maker on geneology.org.


How about some family crafting for Thanksgiving? There are some great crafts ideas hereto do with the kids, plus recipes Wholesale NBA Jerseys China , songs, and learning activities, even computer worksheets for older ?kids?.


Put the family photos in order, and share some memories and tales. Go here to learn the basics of scrapbooking. Take the time to sort them by date, and write on the backs who all the people are.


Make some "Corny" Table toppers. Find directions here -- Thanksgiving place cards and napkin rings.


Make some "Good Manners Napkins." This is so sweet! All you need is cloth napkins, pieces of paper Wholesale NBA Jerseys , pencil, fabric markers, and scissors to write on napkins "Use your napkin," or "Chew with your mouth closed." Go here for these darling reminders to "mind your manners"!


Make Color Me Thankful Posters for each guest at Thanksgiving table. Download poster and instructions here.
Did you know Sarah Josepha Hale, an acclaimed author and editor lobbied for 23 years before she got President Lincoln to establish Thanksgiving as a national holiday in 1863? Spend some evenings reading about the history and traditions of Thanksgiving. Here's one site with information.


Try some of these family bonding activities to share the season and appreciate it, and one another Wholesale Jerseys China Free Shipping , more.

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