Screwdrivers

A screwdriver is a tool used for turning screws so as to drive them into their place. It is a tool to insert and tighten or to loosen and remove screws. It has a thin end, which enters the nick in the head of the screw and with a mechanism to apply torque or force by rotating the tip/end, the screw is inserted into its place. A screw driver is basically a hand operated tool with a cylindrical handle of a size and shape which can be easily held by a human hand, and there is an axial shaft attached to the handle, the tip of which is shaped to fit a specific type of screw. Screwdrivers are available in a variety of shapes, and the tip of the driver can be rotated manually or by an electric or other motor.

Size of drivers used in different size screws

Source: www.acehardware.com/sm-learn-about-screwdrivers--bg-1266832.html

Screwdriver handles
The handles of the screwdrivers are either made of wood or plastic. Top-quality handles made of wood have a bolster on the screwdriver bar and this helps in holding the bar to the handle. The heavy-duty wooden handles extend the entire length of the handle and are headed over with a metal cap at the end . Plastic handles are made of fire and heat-resistant materials and they give excellent grip. Rubber or vinyl is sometimes used on plastic handles to serve as a non-slip or insulating cover.

Types of screwdrivers
Let us now get to know some of the popular screwdrivers , with their uses and features in the following table:

Philips: Having crossed slots with a flat tip, they are used for tightening and loosening Philips head screws and bolts.		Cabinet: These type of screwdrivers have thin slotted tip with straight sides for driving counter bored screws, tightening and loosening slotted screws and bolts. Popularly used in cabinet making.
Standard (Slotted): The standard screwdrivers have single slotted tip which is flared to the sides above the tip and used for tightening and loosening slotted screws and bolts.		Robertson (Square Drive): Having squared flat tip, these are specially designed for tightening and loosening Robertson screws and bolts.
Star (Torx®): Tightening and loosening star head screws and bolts, they are designed to prevent strippings by having a more flat contact surface with the screw head.		Hex (Allen Head): For tightening and loosening recessed hexagonal bolts, screws, the hex screwdrivers are used and they can be used in place of Allen wrenches. They are mainly used in repair work in the electronics field, for tightening socket-set screws.
Clutch Head: They are used for tightening and loosening clutch head screws and bolts. They have four points of contact, lock into the screw head when turned counterclockwise.		Nut Driver: Available in varied sizes from 3/16" to ½", they are used tightening and loosening hexagonal screws and bolts.
Tack Claw: Having curved claw tips, they are used for pulling tacks and small nails.		Offset: These screwdrivers are used for tightening and loosening screws in tight spaces. They are available in many combinations.
Jeweler's: Used for performing fine or precision work		Yankee Screwdriver: Having interchangeable bits, they rotate to turn the screw when the handle is pushed.
Ratcheting Screwdriver: They are available in multi-piece sets having interchangeable bits and sockets. With reversible ratcheting handles, they help in driving screws and nuts much faster.

Magnetized tip screwdrivers
There are some other variety of screwdrivers which are very popular in the market today. These are the magnetized tip screwdrivers. They have magnetized tips, the blades can range from Philips to Hex and other types and these are convenient when guiding screws to holes or otherwise inaccessible areas. They can also be used to retrieve dropped screws and nuts.

Buying tips: Quality Indicators
There are several factors that help judge the quality of screwdrivers such as:

• Blade Metal: If the kind of metal in the blade is poor quality, it will chip and crumble under pressure.
  
  
• Amount of grinding on the tip: If the tip is improperly ground and flares too much, it will rise out of the screw slot.
  
  
• Handle and bar attachment materials: The materials used to make the handle and the bar attached to it also indicate the quality of the screwdrivers. If the blade is not attached firmly to the handle, it will eventually loosen and slip in the handle.
  
  
• Screwdriver Tips: Tips used on the screw drivers may be of many kinds. Important kinds of tips are regular, cabinet, Phillips, Frearson, Torx, clutch-head, hex, Bristol multi-spline and square-tipped.