There is likely a screw somewhere inside a large percentage of the things in your house. Pretty much every electronic device has them, and most pieces of furniture. We at RH Nuttall come across them everyday thanks to our products. They are an inescapable part of modern life, but for the vast majority of the time they cause no problems.
Until it comes time to unscrew them.
Then the games begin.
We’ve all been there. The new sofa needs building, but you haven’t got the right screw head. You have to track somebody down with an entire case worth of screwdriver heads, and even then they haven’t got the right size. Why are there so many? How many are there? Well. . .
These screws don’t include a slot in the top, instead requiring a wrench to remove them. They tend to be quite thick and heavy, so are commonly used in heavy industry, where tampering is unlikely, due to the relative widespread availability of corresponding wrenches. In your house, they are likely to be placed inside big items comprised of wood or steel.
One of the two most common screw head types, these slotted heads tend to be built for ease of use. The indented slot tends to reach to the outside of the head, so while they can be undone with screwdrivers, it’s also possible to unscrew them with knives and a whole wealth of other household items. For this reason, they don’t tend to be placed inside items that must remain structural sound. More often than not, they are used for tasks where the screw can be easily inserted or removed, such as picture frame hanging.
Phillips, Frearson and Pozidriv
The more common screw seen within consumer goods in modern society, the Phillips head is named after it’s creator, Henry F. Phillips. The slot is indented, but without reaching the ends of the head like the design seen on the slot headed screw. The variations above are the Frearson (middle), and the Pozidriv (right). While the Frearson’s main advantage is the fact that one Frearson screwdriver can fit any Frearson screw size, the Pozidriv is simply a strengthened Phillips, designed with reduced smooth edges as so to minimise the chances of a screwdriver slipping out.
Square and Hex
These screws are where things start to get complicated. These can’t be undone with a universal screwdriver – they require specific screwdrivers, tailor made to fit the slots. Why do they exist? Well the commonly held belief is that manufacturers utilise them to force their clients to buy the corresponding tool kit. Most car manufacturers will use a unique design, so you will have to fork out just that little bit more for the branded tool kit when you buy a new car. But they do come with the benefit of being hard to remove, which will deter others from tampering with them.
While the screws above are designed to be removed, some are manufactured to be incredibly difficult to remove. Some, such as the anti-tamper screw seen in the video here, are built with break away screw heads. Once the screw is inserted, the head can be removed, leaving nothing but a smooth domed bolt. The screw head shown in the diagram above is a “one-way” screw. It is designed to be easy to screw in, but with smoothed out edges going in the opposite direction, preventing anybody from unscrewing it. Both are typically used in prisons and on street signs.
Those are the screws you are most likely to come across. But this is barely scratching the surface!
Below is a collection of just some of the screw heads we’ve come across!
Image credits: Wikipedia.org