Know Your Tools: The Flat-Head Screwdriver

Flat head screwdriver
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A flat-head screwdriver is a screwdriver with a wedge-shaped flat tip, used to tighten or loosen screws that have a straight, linear notch in their heads.

This is arguably the most common tool on the planet—the ubiquitous flat-head screwdriver. Every junk drawer has one or two in it. While it comes in many shapes, the concept is always constant. There will be some sort of handle attached to a steel shaft that is flattened into a wedge shape at the tip.

This flat tip is perfectly sized to fit into a screw with a straight head slot with a corresponding shape. Different screwdriver sizes are available to fit screws with different-sized slots in their heads. 

History of the Screwdriver

So old is this tool that the first historical mention dates back to the 1500s. In its modern form, the flat-head screwdriver was probably invented in about 1744 in England, where it was known as a "turn-screw"— a type of bit used as an attachment in a carpenter's brace-and-bit tool. The hand-held version first appeared in the United States in the 1800s, and the only form of the tool was the flat-head for the next 130 years or so, when the Phillips head came into use, based on a patent by Henry F. Phillips. 

A Most Versatile Tool

While not the best screw design by any means, the flat-head was the first, and because of this you'll find countless things that require a flat-head screwdriver to remove or install.

Even though the flat-head has been somewhat replaced by screw types like the Phillips head, square-drive heads, pozi-drive, and Torx-type heads, you'll still find the need to use a flat-head screwdriver from time to time.

While it's one of the most commonly found tools (or perhaps because of this) the flat-head screwdriver is also one of the most abused.

It is often substituted for any number of other tools when they are not be available. Clever (or sometimes just impatient) handymen and handywomen will put a flat-head screwdriver to work as a chisel, as a nail-puller, as a paint-scraper, as an awl, or as a small pry-bar. DIYers who are experienced know that it's best to never throw an old flat-head screwdriver away, since it can often be ground down, bent, filed, or otherwise adapted into all kinds of practical uses around the house.

You have to be careful when leaving the tool's comfort zone, however. Prying too hard can cause the end of the tool to snap off, leaving you with little more than a fishing weight in your toolbox. Using it as a chisel and pounding on the end with a mallet may also cause the handle to snap into pieces. There's nothing less useful than a flat-head screwdriver with a broken handle. That is perhaps the only time when you'll need to throw it away. 

Correct Use as a Screwdriver

There are flat-head screwdrivers in many sizes, so choose the one in your toolbox which most closely matches the job you need to do with it—meaning the one whose blade best fits the screw slot. The slots in flat-head screws don't just require a wider tip as the size of the screw increases, it also needs to be thicker.

Flat-head screwdrivers vary in thickness proportionate to their width, which should give you excellent grip in the slot of a screw. The principal drawback of a flat-head screwdriver is that it's prone to slipping out of the screw slot, so choosing a screwdriver that fits just right is key to correct use. The blade should fit fully down into the slot on the screw, with little, if any, wiggle room.  This is just one of many inexpensive tools that you should have in your toolbox.