The Evolution Of Screw Heads And Matching Screwdrivers

Screwdrivers are used for twisting screws and fasteners and are an indispensable tool for DIY projects and repairs. They are made up of three parts: the handle, the shaft, and the screwdriver tip. The handle is designed to provide a secure grip, the shaft connects the handle to the tip, and the tip fits into the screw head.

There are several types of screwdrivers, each designed for a specific type of screw head. The most common types include flathead, Phillips, Pozidriv, Robertson, Torx, and Hexagon. Flathead screwdrivers have a single flat blade that fits into a slot in the screw head, while Phillips screwdrivers have a cross-shaped tip with four arms. Pozidriv screwdrivers are similar to Phillips but have additional points of contact for better grip. Robertson screwdrivers have square-shaped tips, Torx screwdrivers have a star-shaped tip, and Hexagon screwdrivers have a hexagonal-shaped tip.

Other types of screwdrivers include spanner screwdrivers, which are used for tamper-proof screws with two round pinholes; Japanese Industrial Standard (JIS) screwdrivers, which are designed for JIS screws commonly used in Japanese electronics; and clutch head screwdrivers, which have a unique bow tie-shaped tip used for security screws.

The right screwdriver head is crucial for a successful project as it ensures proper usage, prevents damage, and improves efficiency.

Flathead/Slotted Head Screwdriver

Flathead or slotted head screwdrivers are not used extensively in residential construction anymore, but you will need them to remove or install plate covers on outlets and switches and in other instances where it is important not to over-tighten a screw. You can also find them used in furniture construction and small cabinet-making projects.

Flathead screwdriver bits are available for ratcheting screwdrivers and drills, but it is also a good idea to keep a handful of flat manual screwdrivers in your tool bag. They will come labelled by both the size of the tip and the length of the steel shank. Tip sizes vary, from fractions of millimetres (which are tiny enough to tighten eyeglass screws) up to an inch or larger (fit for industrial-size screws). When matching a slotted screwdriver to a flat screw, pick one that matches the width and depth of the slot on the screw head in question.

Flathead screwdrivers are generally made up of three parts: the handle, the shaft or shank, and the drive tip or bit. The handle is the part of the screwdriver that the user holds and twists. While some may be wood or carbon fibre, they are generally made of hard plastic or nylon, and some feature rubber grips. The shaft or shank is the long section that connects the tip to the handle. These are generally smooth and polished for easy cleaning, but some may be hexagonal or partially hexagonal to allow the user to place a wrench on the shaft. The drive tip or bit is arguably the most important part of the screwdriver as it determines which fasteners the screwdriver can engage to tighten or loosen.

Phillips Screwdriver

A Phillips screwdriver is a tool used for driving or removing screws. It has an X-shaped tip that fits inside the X-shaped notch of a compatible Phillips-head screw. Phillips screwdrivers were developed in the 19th century as an improvement over flathead screwdrivers. The X-shaped head provides better traction or grip when driving or removing screws.

The Phillips screwdriver is named after Henry Frank Phillips, an American businessman from Portland, Oregon. The original Phillips screw was patented by John P. Thompson in 1932, who then sold his self-centering design to Phillips in 1935. Phillips formed the Phillips Screw Company in 1934 and successfully promoted the adoption of his product.

One advantage of the Phillips-head screw design is its self-centering property, which is useful on automated production lines that use powered screwdrivers. The design also helps to prevent cam-out, which occurs when the screwdriver tip slips off the screw head due to misalignment or excessive torque. However, the Phillips design is sometimes criticised for its tendency to cam out at lower torque levels compared to other "cross head" designs.

It is important to note that a Phillips screwdriver should not be used with a Pozidriv screw, as this can damage the head of the screw. Pozidriv screws have additional radial indentations that make them visually distinct from Phillips screws, and they are designed to allow for higher torque application and greater engagement.

Pozidriv Screwdriver

A Pozidriv screwdriver is an improved version of the Phillips screwdriver, designed to address the cam-out problem associated with Phillips screws. Cam-out is when a screwdriver slips out of a drive recess due to torque exceeding a certain limit. The Pozidriv screwdriver was developed by the American Screw Company and GKN Screws and Fasteners, and it first emerged in 1962.

The Pozidriv screwdriver has a much shallower angular tip with eight radial slots, compared to the Phillips screwdriver's four. The four primary slots of the Pozidriv screwdriver are in a cross pattern, with a secondary set of four smaller slots set at a 45-degree angle to the primary ones. This design gives the Pozidriv screwdriver better torque transmission and reduces the chance of cam-out or slipping when high torque is applied.

While it is technically possible to use a Phillips screwdriver on a Pozidriv screw, it is not recommended as it can lead to tool damage and inefficient work. The risk of cam-out is much higher when using a Phillips screwdriver on a Pozidriv screw, and there is also a chance of stripping the screw head or damaging the tools.

Robertson/Square Screwdriver

Robertson screwdrivers, also known as square screwdrivers, are used for Robertson screws, which feature a square-shaped socket in the screw head and a corresponding square protrusion on the tool. The tool and socket have a slight taper, which makes inserting the tool easier and helps keep the screw on the tool without the user needing to hold it in place. Robertson screws are commonplace in Canada, although they have been used in other countries and are becoming more common. They are often used in woodworking and general construction, as well as in electrical applications.

Robertson screwdrivers have several advantages. They are easy to use one-handed, allow the use of angled screwdrivers and trim-head screws, are self-centring, and can be easily removed if painted over or old and rusty. In industry, they speed up production and reduce product damage.

The original Robertson screw and screwdriver were invented in 1906 by P. L. Robertson, who received a Canadian patent in 1907 and a US patent in 1911. Robertson's breakthrough was to design the socket's taper and proportions in such a way that the heads could be easily and successfully cold-formed, making the screws a valuable commercial proposition. Today, cold forming remains the most common fabrication method for Robertson screws, although rotary broaching is also commonly used.

There are several Robertson screwdriver products on the market, including:

• The Williams SuperTorque Robertson Screwdriver, which features a 3-component handle for maximum comfort grip, a sandblasted tip for greater screw-tip adherence, and chrome blades to prevent corrosion.
• The Klein Tools #2 Square-Recess Tip Screwdriver, which features a 4-inch shank, a colour-coded red handle, a round shank with a Robertson tip, a Cushion-Grip™ handle for greater torque and comfort, and a precision-machined tip for an exact fit.
• The Milwaukee 4-inch #2 Square Screwdriver, which features a cushion grip.

Torx/Star Screwdriver

Torx screwdrivers are used to drive or remove Torx screws, which have a six-pointed star-shaped notch. This six-pointed star shape is also known as a hexalobular socket screw drive. The Torx screwdriver is designed to reduce damage to screws from repeated use and is often used in the appliance, electronic, and security industries.

The Torx screwdriver was designed in 1967 by Camcar Textron to permit increased torque transfer from the screwdriver to the screw compared to other types of screw drives. The design is also resistant to cam-out, which is when the screwdriver tip slips off the screw head. This is a common issue with flathead and Phillips screwdrivers. The Torx screwdriver is also less likely to strip the screw head.

Torx screwdrivers are available in a variety of sizes and lengths and can be found as manual or electric tools. They are also available as precision screwdrivers for working with electronics and computers.

A Security Torx screwdriver is a type of Torx screwdriver used with a specialty tamper-proof Security Torx screw.

Frequently asked questions