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At first glance, the main difference between a flathead screwdriver, or more properly called a slotted or flat blade screwdriver, and a Phillips screwdriver should be patently obvious. A flathead has a single blade, and a Phillips has two blades in the shape of a cross. Attempts to use a flathead tool on a screw designed for a Phillips usually won't be successful, and a Phillips screwdriver could never be used on a slotted screw. Both are considered "driver" tools, which means they are used to force bolts or screws through various types of material.
There are differences beyond the blade shapes, however. The flathead has been in use far longer than the Phillips. When screws began to replace hammer-driven nails in the manufacturing process, the single slot screwhead was almost universal. A flathead screwdriver became an indispensable tool for woodworkers and other commercial artists. This version is still considered the default model to this day, even with its inherent problems.
The Phillips screwdriver, by comparison, is still a rather new tool option. Invented by Henry Phillips, a tool company owner working in the 1930s, the screwdriver and accompanying screws were intended to provide a safer alternative to the traditional flathead. Henry Phillips wanted a screwdriver that would prevent a damaging process called overtorquing.
Traditional screwdrivers at the time often allowed the user to put too much twisting force, or torque, on the slotted screws. By designing a cross-shaped blade and corresponding cross-shaped screws with a slight depression, Phillips could apply more torque than with a flathead. This mechanical advantage allows users to use their twisting strength more efficiently. The depressions in the screws, however, forced the blades of the Phillips to slip out before any damaging overtorquing could occur.
One flaw in the flathead design is the relative strength of the blade, or bit. When a flathead bit is attached to a powered driver, the added force can cause a weaker blade to snap off. In addition, the slotted screw may become stripped if too much torque is applied. This is why the use of the flathead screwdriver is generally limited to woodworking and other light-to-medium industrial applications. Only the strongest flathead driving bits are used for high-torque manufacturing processes.
By comparison, a Phillips screwdriver is very well-suited for industrial processes. Once the Phillips bit is seated securely in the Phillips head screw, the operator can apply much more torque for fastening. Since the screw will force out the bit at the first sign of overtorquing, there is less risk of damage to the product or the bit.
Some modern screws accept both flathead and Phillips screwdrivers, although some experts suggest using a Phillips for tightening and a flathead for loosening the screw. One advantage a flathead has over a Phillips, however, is universality. In case of emergency, a number of other flat metal objects, such as coins, butter knives or keys, can be used to tighten or loosen a screw. It is much more difficult to duplicate the fit of a Phillips head.
What Is a Phillips Screwdriver?
In the 1930s, Henry Phillips created the Phillips screw. This screw was designed to accept more force than the traditional single-slot screw, which made it ideal for heavy-duty applications like automotive construction.
The Phillips cross-shaped slot was designed in such a way to make the screwdriver stay put and to provide the user more leverage. However, although this was a great and useful screw, the standard flat-head driver didn't suit the new design.
Since a standard flat-head didn't fit cleanly into the head of a screw, Phillips designed a different screwdriver to fit his new invention. This new screwdriver came to be known as the Phillips screwdriver and completed what is now known as the Phillips system.
One of the most significant advantages of the Phillips system is that the screwdriver is self-centering. That means it fits neatly into the head of the screw, making it easier to get a good grip while turning. When it comes to screwdrivers, a good grip on the handle makes completing a job much more manageable and, in some cases, safer.
Another unique feature of the Phillips screwdriver is that it will "cam" out when the screw can't go in any further. In other words, the screwdriver will pop out of the head when the screw reaches its limit. This helps keep the screw from being overdriven, which can damage the screw, the screwdriver, and the material the screw is in.
What Is a Flathead Screwdriver?
The flat-head, or slotted flat blade, screwdriver, has a much longer history than the Phillips. Dating back to the 16th century, the flat-head is used to tighten screws, bolts, and fasteners of all sizes. Like the Phillips, it gives the user significant leverage when tightening screws.
The flat-head screwdriver is incredibly versatile, although using it for purposes other than tightening screws can damage the tool. Regardless, it's often used as a chisel, ice pick, or paint scraper, or to get leverage when pulling screws. Because flat-heads are so frequently put to purposes they aren't intended for, they often don't have a long lifespan.
Flat-heads come in a lot of sizes. The key factor when choosing a size is remembering that a larger screw requires a fatter and more sturdy screwdriver. In other words, although a smaller screwdriver might fit a larger screw, the amount of force needed to loosen that screw could easily bend or break a smaller tool.
What Does a Phillips Screwdriver Look Like?
A Phillips screwdriver has a unique look. Like other screwdrivers, it has a round, steel shaft attached to a handle typically made of resin or rubber. However, the most significant difference is that the head is a cross-shaped wedge. The shape of the head makes it easy for the tool to self-center and keep a solid grip on the screw.
Phillips screwdrivers come in five sizes that range from zero to four, with zero being the smallest. Sizes one and two are the most commonly found options. Size two is used for standard-sized screws, while size one is meant for miniature screws.
In addition to the five standard Phillips sizes, smaller options are available. Thmese saller tools are typically sold in sets and are often used by jewelers to tighten very small screws, such as those you might find on a watch or locket.
The most important thing to remember about selecting Phillips screwdrivers is that they're very precise. A size-zero Phillips won't work with a size-four screw because it won't be able to center itself properly in the screw's head.
You should also bear in mind that overworking the screw can damage both it and the screwdriver, rendering them both useless.
What Does a Flathead Screwdriver Look Like?
A flat-head screwdriver has a very simple shape. Like the Phillips, it has a steel shaft attached to a handle. However, the tip of a flat-head is cut into a wedge that fits cleanly in screws and fasteners with straight notches.
Flat-heads come in many sizes based on the width of the head. For example, you can purchase flat-head screwdrivers that are only a few millimeters wide and others that are a half-inch wide. You can also find them in miniature sizes that work for things such as jewelry or eyeglasses.
The benefit of flat-heads is that, despite their varied sizes, you can often use a smaller size with a larger screw. For example, while a 1/8 inch flat-head is smaller than a 5/32 inch screw, you can still use it in a pinch.