Screw Head Types
There are many different screws with different characteristics. Long, short, thin, fat, round, flat and more. Do you always know what screw you need for the job you are doing?
It is fairly straight forward when it comes to inserting the screw to complete your job however, the tricky bit is choosing the correct screw and not only that, the screwdriver. The screwdriver must be the correct type to fit the certain screw head. For example, a Phillips head screw would need a Phillips head screwdriver.
The slotted screw has been around the longest. This is the traditional screw head in which used to be the only head type available. The slotted head is basically one line through the middle of the head in which the screwdriver would fit. Once the edges of the slot is burred, the screw then becomes unusable.
This head type was brought in to improve the quality of the overall performance when in contact with the screwdriver. This head type has four points of contact instead of two. This means that either a Slotted head screw driver or Philips head screw driver can be used. However, this type of head also does tend to burr.
Pozi drive screw
The Pozi drive screw has a total of eight points of contact, this is done by adding a second cross to the first cross and it improves the contact of the driver to the screw. This is more versatile than a Phillips head and also has a superior grip. This head may be used with a slotted screw driver or a Pozi driver.
Square recess or Robertson screw
This head type matches the head type on a square headed screw driver. However, this is not the only driver which can used as a slotted driver, from on corner of the head to another, can be used with this screw. This head type works very well with the driver in that they slot together easily therefore gives an easy drive.
These head types are made to extend above the surface and is driven by using either a hexagonal driver or a spanner. These fasteners are very similar to hex bolts. They differ mostly in that they are used to tighter tolerances than the corresponding bolts.
Torx head screw
These head types have a six pointed recess which makes the drive easier in that there is a larger surface area. They require a less common driver to suit them called a Torx driver.