Phillips heads have a cross-shaped tool indent. Hex socket screws require an Allen wrench, while hex screws are entirely hexagonal without an indent for a tool, meaning it needs a wrench or socket wrench. Square indentations are also known as Robertson screw heads and require a special driving tool.
The slight taper of the socket and drive allows for a “cling” fit, an especially useful feature when driving lots and lots of screws vertically from above.
Robertson's design consists of a tapered square-tipped screwdriver that fits into a matching square recess (the “socket”) in the screw head. This design makes a Robertson screwdriver less susceptible to cam-out than a Phillips driver because the driver bit inserts deeper into the screw head.
Although the terms "square drive" and "Robertson" are often treated as the same in catalogs, the difference (as I understand it) is that Robertson tools and screws have a slight taper to the square recess and the square drive ones do not. Most online sources claim that the tapered design is superior.
Most historians attribute its lack of popularity in the United States to Henry Ford. Having been nearly bankrupted by shady European licensees, Robertson refused to license his invention to Ford. Without a guaranteed supply, Ford turned to the Phillips-head screw, cementing its reign in American industry.
It is important to note, however, that this advantage of the Roberston screw can also lead to the screw bits getting stuck inside the screw heads from time to time.
For Philips, Torx, and Robertson Screws
Grasp the nail with a pair of pliers to turn it. You can even try using a hammer to tap the nail into the tiny screws, improving the grip. You could also try working with a drill and drill bit. Take the same hammer you used for the nail and tap the drill bit into the screw.
Most of us call Robertson screws “square drive” or “socket head” screws. They were invented by Canadian traveling salesman Peter Robertson around 1906.
Robertson sizes are denoted with colours instead of numbers. The medium-size that's most common is red; anyone who calls this a "#2 Robertson" deserves arched eyebrows and a thorough looking-down-on. Black is the largest size, with green being smaller; yellow and orange are smaller still but much less common.
This was a great idea at one time and led to the screw's popularity. However, higher torque applications require a different approach. Robertson screws are advertised to be able to handle more torque before the dreaded cam out. The square design also allows for self-centring of the driver bit.
Robertson Screwdriver
Robertson screwdrivers come primarily in four sizes: #0, #1, #2 and #3. You're most likely to need a #2, followed by #1 and #3. Klein Tools' #2 Square-Recess Screwdriver offers the same features as Klein's fine Phillips screwdriver.
Only genuine Robertson® bits feature Cling Fit with a genuine Robertson® tip. Cling Fit provides for maximum recess penetration for straight driving power with no wobble. #0 size is Yellow, #1 size is Green, #2 size is Red, and #3 size is Black.
Our Robertson® brand screws feature the Robertson drive head and its famous "cling-fit." A Robertson drive screw head has a slightly tapered, square-shaped socket in the head and a Robertson driver has a matching shaped protrusion on the tooltip.
Since our inception in 1908, our company has been committed to maintaining the highest level of excellence in our products and services for valued customers. We supply multi-purpose screws for every application, from decking, cabinetry, vinyl window & doors, sheet metal, framing and wood applications.
The strongest screw heads are typically star-shaped, Torx bits, or square-shaped, Roberts bits. However, a well-fitted Philips head is also strong.
Robertson screws are advertised to be able to handle more torque before the dreaded cam out. The square design also allows for self-centering of the driver bit. You get a nice snug fit and ultimately less struggle. They are easier to use one-handed as well with such a design.
A flat head screwdriver is used for tightening or loosening screws that have straight or linear (slotted) notches in their head. Not only are they the most common type of screwdriver to have, they are also one of the most common tools full stop.
The green #1 drive bits are 1”, 2” or 4” long and fit screw sizes #5, #6 and #7. The red #2 drive bits are 1”, 2”, 4” or 6” long and fit screw sizes #8, #9 and #10. The black #3 driver bits are 1”, 2”, 4” or 6” long and fit screw sizes #12 and #14.
Offset Screwdriver
This tool is ideal for working in tight spaces where a standard screwdriver would be too long to fit, like behind a wall, in the ceiling, or under a heavy appliance. Offset screwdrivers can come in various sizes and lengths, as well as different screwdriver heads, like Phillips or flathead.
Torx or Star Screwdriver
Torx is the trademark for a type of screw head with a six-point star-shaped intrusion, hence the generic name star screwdriver. These exist to ensure even more torque can be applied, in mechanical production, for example.
By design, Torx head screws resist cam out better than Phillips head or slot head screws. Whereas the tendency of Phillips drivers to cam out under excessive torque has been listed as a feature preventing damage to the screw-head or driver, Torx heads were designed to prevent cam-out.
Pozidriv screws are externally threaded fasteners with torquing heads, which feature a cruciform socket with radial indentations that are set at 45 degrees from the main cross. Pozidriv describes the screw drive type of the socket and driver, and is one of the most common screw drives used worldwide.