SQUARE RECESS SCREWDRIVER NO.2

The various drives:

Slot screw drive:

The drive has a single slot in the screw head and is driven by a flat-bladed screwdriver. This was the first type of screw drive developed. The screwdriver is sometimes called a flat-blade, flat-tip, slot-head or a flat-head screwdriver.

Phillips:

The drive was invented by Henry F. Phillips. The Phillips screws have cross-slots that look like an X stamped into the head. The drive was patented in the 1930's. This drive was invented to become a vast improvement from the antique slotted screw, which tended to cam-out easily. Nowadays, the Phillips screw is easily mistaken for a Pozidrive screw.

Pozidrive:

The drive is an improved version of the Phillips drive. Greater torque can be applied on a Pozidrive screw. The Pozidrive screws and the screwdriver can be distinguished by a second set of radial indentations set at a 45° from the cross recess. The design is intended to decrease the likelihood that the Pozidrive screwdriver will slip out. The disadvantage of the Pozidrive is that is visually similar to Phillips and that many people are unaware of the difference or do not own the correct screwdrivers.

IMPORTANT:
The screws having a pozidrive head can be unscrewed by a Phillips screwdriver, but a Phillips screw cannot be unscrewed by a Pozidrive -  It will severly damage the screw and the tip of the screwdriver.

Robertson (Square drive):

The drive is also known as a square drive. Some people might refer to it as Scrulox screw drive. The screw head has a square head. The tip of the screwdriver is tapered to make it easier to insert into the screw. Robertson screwdrivers are easy to use with one hand. It also allows the screw to be placed on the screwdriver prior to driving it in position.

Torx:

The drive uses a star-shaped recess in the screw head with six rounded points. It is designed to permit increased torque transfer compared to other screwdrivers. Torx is very popularly used in the automotive, electronics and woodworking industries. It has a very high resistance to cam-out and has an extended bit life.

Security Torx:

The drive is similar to the standard Torx drive, but has a small pin in the centre of the the recess. This drive is also referred to as a tamper-resistant Torx drive.