Knowledge about the various types of screw heads, method & requirement

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Types of Screws and Where These are Used
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• All screws and not the same and knowing which
  screw to use is important to ensure that its
  doing its job right. For instance, the screw that
  holds your furniture together will not work if
  you decided to hammer it into your wall to hang
  your pictures. The right screw for the right job
  makes all the difference whether it is for
  carpentry or for building a ship.
• There are many kind of screws and there are many
  ways of classifying them. One of these is to
  classify them according to the job requirement.
  For instance, brass machine screws, that are used
  for motor casing. You can also classify screws
  according to the driving method and head shapes.
  Here are the classifications in detail

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By Driving Method

• This classification is based on the shape of the
  slot at the screw head. This will also determine
  the shape of the screwdriver or drill head. These
  are
•  
• Slotted This is the oldest and most common
  shape. The slot at the head is just a linear
  diameter and can be used with a standard
  screwdriver.  
• Philips The head has a cross-shaped slot that
  does not reach the edges. It requires a
  Philips-head screwdriver. This shape offers a
  more compact grip to the screwdriver head.
• Combination This is a combination of the slotted
  and Philips. It has a cross-shaped slot like a
  Philips head with one of the linear slots running
  to the edges like a slotted head.
• Allen/Hex It has a hexagonal slot that is
  tightened with an Allen wrench. This type of
  screw can only be loosened by a socket wrench.
• Square It has a square-shaped slot.
• Star The star-shaped indentation is extremely
  efficient in preventing stripped heads.

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By Head Shapes

• This classification is according to the shape of
  the screw head. Some of these may not even have a
  slot at the top. These head cannot be fastened by
  a screwdriver and need a wrench.
• The different shapes we find in screws are Flat,
  Oval, Socket cap, Pan, Round, Button, Hex,
  Flange, Truss, Full bearing, Washer-faced,
  slotted-hexagon, Flat hexagon socket, Countersunk
  hexagon slotted, Countersunk, Raised countersunk,
  Philps round pan, Philips round and so on.

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By Job Requirement

• The shape of the screw head does not matter here.
  The material and the shank shape are more
  important, like brass machine screws. Both these
  factors determine where the screw can be used.
  The different type of screws here are
• Wood screw These are screws used with woodwork.
  The screws are unthreaded at top with coarse
  threads at the bottom for better grip on
  penetration. This ensures that the screw will go
  in smoothly without excessive splintering. There
  are various sizes and types here. These can be
  wood or metal like brass, bronze and steel. Since
  these are used in making furniture, the type
  should also be picked for aesthetic purposes,
  such as round-headed screws.
• Machine screw Made from machining, these screws
  have the advantage of customization. A typical
  screw will have very clean threading and a much
  better grip. Machine screws like brass machine
  screws are used in pre-drilled holes. These are
  used in motor casings, electrical terminals etc.
  However, these cannot be used with wood.

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• Sheet metal screw These screws have full thread,
  but a wide variety in head type. The screws have
  the advantage of customization and are used in a
  wide array of applications, such as with
  plastics, rubber, plywood and metal. However,
  these cannot replace the wood screw. There are
  many types of screws that come under this
  category and the right screw depends on the
  material you will be using.
• Drywell screws There are two types of drywall
  screws finely threaded (S-type) and coarsely
  threaded (W-type). Finely threaded screws are
  used to attach metal studs, while coarsely
  threaded screws are used to attach wood to
  drywall. Both types have sharp points that makes
  drilling fast and easy. In addition, the finely
  threaded do not need any pre-drilling because of
  their pointed ends.

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• These are the different types of screws that you
  have to look for. When buying a screw, you will
  notice that it will fall into different
  categories.
• For instance, a brass machine screw is a machine
  screw which can have different types of head.

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