If you’ve ever taken a trip to your local hardware store to buy the best fastener for your project, you already know how overwhelming that experience can be, given the plethora of options available.
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Most, if not all woodworking projects require some type of mechanical reinforcement, and the most popular fastener to get the job done is wood screws, and not nails as you may have thought.
Wood screws — contrary to what the name may suggest aren’t fasteners made from wood, but are screws common to woodworking projects rather than those used in drywall assembly, construction work or for deck/fence building.
Wood screws when used correctly i.e. in combination with wood glue can make the screw joints nearly indestructible. All wood screws are made up of four main components — head, shank, threads and tip.
Head Types of Wood Screws
Wood screw heads consist of two components — head shape and drive type. Drive is basically the shape of the head, where you put the screwdriver tip to drive the screw into the wood. A good quality screwdriver set should contain most of the popular types required today. There are myriad different screw head types to choose from, most notably:
Slotted (flathead screws)
This is the traditional screw head type, and as you might have guessed is a straight slot across the head of the screw. Slotted screws were once a preferred choice for woodworkers, and even though they are readily available, they are rarely used, owing mostly to their tendency to slip when driving them.
Also referred to cross-head screws, Phillips screws were conceived in the early 1930’s, and are hailed as a great improvement over slotted screws. They feature crossed slots, which provide screwdrivers with a better grip when turning.
However, they do have a tendency to cam out, which can ruin the head as well as the screwdriver. Phillips screws are available in an assortment of different sizes, so it is important that you get a driver to match and one that fits snuggly in the drive.
Pozidriv screws, or as many people often (incorrectly), call them Pozidrive, is very similar in appearance to a Phillips head screw. It was created and introduced to the market by GKN, an old British firm.
The GKN stands for Guest, Keen and Nettlefolds, an amalgamation of steel and toolmaking companies based in Darlaston, South Staffordshire UK.
When the patent on Phillips head expired, GKN introduced Pozidriv, which makes cam-out less likely by having a greater area of contact between the screw head recess and the screwdriver.
It is easy to visually spot the difference between Phillips and Pozidiv by the 4 small star shape grooves that are present on the Pozi head, which are not on the Phillips head.
The Pozidriv drivers have corresponding flutes visible at the tip.
Square-Head – Robertson Head
This relatively new drive type is a great improvement in the wood screw segment and is designed to offer a better grip and prevent stripping compared to flathead and Phillips type screws. Also known as Robertson screws, this type of screw is harder to find in the USA, but is easily available in Canada.
Star Drive – Torx
Dubbed as Torx wood screws, star drives are an absolute favorite for several DIYers for many good reasons. The heads on these screws resemble a star shape with six sides, hence the reason for the name.
Torx screws greatly reduce the chances of cam out, and the driver almost never slips out of the screw head. They can handle a fair amount of torque, and in most cases won’t snap even when over-tightened.
Torx screw is a brand in the star drive space, but there are other noteworthy brands to choose from including Pozidriv and Polydrive. Each brand showcases a slightly different drive shape, which is probably why a driver tip is often included in the box of screws.
Apart from the ones mentioned above, there are many other drive types in wood screws, where some even combine different drive types that can be driven by different driver bits such as a star-shaped driver bit or square-shaped driver bit.
Head Shapes of Wood Screws
Just like drive types, there is an array of different head shapes, but the following three are the most common.
This is where things can get a bit confusing, given that it’s easy to mistake a screw with a flathead, and a slotted screw that we refer to as flathead screws. Since we’re referring to woodworking in this article, flathead wood screws have tapered recesses, and a beveled head that sits flush with the wood.
It is the most common type of wood screw to use, and offer the most holding power compared to other types of wood screws. Even though you can simply drive a flathead screw into wood, you can also use a countersink bit to drill a pilot hole if you’d like the screw head to rest below the wood surface.
Also referred to as panhead screws, these can have either deep or shallow domes. Even though round-head screws aren’t used much in woodworking, they do come handy when attaching other materials to wood such as plastic or metal.
These are a combination of the aforementioned two types of screws, and feature a slightly tapered head, on the bottom, with a slightly rounded top. Oval-head screws offer a more decorative look, as the screw head protrudes slightly above the surface of the wood.
Specialty Wood Screw Head Shapes
Washer-head screws – similar to round-head screws, washer-head screws are embedded with small washers into their heads. The design of the heads prevents them from sinking in too deep, which makes them a good choice for applications that require the use of power drivers.
Sometimes called “mushroom head” screws, Truss-head screws are not to be confused with oval-head screws because they have a flatter and larger head. They are a great choice for applications that require great holding power, but without protruding too far such as mounting drawer slides.
These screws have cylindrical screw heads, but are names for their close resemblance to flat cheese wheels.
6 Common Wood Screw Types
Structural screws are a fairly recent development. They are normally manufactured from heat-treated steel which has high strength characteristics. They are easy to fix without the need for pilot holes compared to the previous alternative, lag screws.
Standard Wood Screws
These are the most common type of wood screws you will encounter when working with wood, and are available in a spectrum of different lengths and gauges. They are partly threaded, and are a perfect choice for most non-structural applications.
This type of wood screws is a go-to choice for many woodworkers for use in shop projects and jigs. Just as the name reveals, they are mainly used to secure drywall panels to wooden or metal surfaces, and features shanks that are thinner shanks than standard wood screws, and fully threaded shanks.
Deck Wood Screws
This is the type of wood screws you want to use for all your outdoor woodworking projects, and are made from either copper or hardened steel, which makes them corrosion resistant. They generally have larger heads and deeper threads to help accommodate more weigh, and can be used for both hardwood and softwood applications.
Pocket Wood Screws
Preferred for their self-drilling abilities, pocket screws feature a wider head mated with a flat shoulder. They are best suited for wood that has pocket holes, and a feature a square drive for easy installation.
Machine Wood Screws
It’s easy to machine screws apart from other types of screws as they lack a pointed tip. They feature fully threaded shafts, and are occasionally used to fasten a couple boards together.
Sheet-Metal Wood Screws
These screws in most cases have pan heads, and feature a tiny and sharp point to easily drive them into sheet metal such as when installing heating ducts.
When deciding on the right wood screw for the job, you also need to consider other aspects such as the material the fastener is made from, which commonly is steel, stainless steel, hardened steel or grass.
Furthermore, it is worth noting that hardwood can be brittle, so it is best to first drill countersunk pilot hole, and then drive the screws into the wood to prevent cracking and damage.