Screws are arguably the single most important fastener out there. For almost any project, DIY or professionally done, screws are probably going to come into the equation because of their ease of installation and unmatched strength.
By choosing quality self-tapping screws from a reliable source like RS, you put yourself in the best position possible. Whether you’re a pro or a DIYer looking to take on another project, self-tapping screws can help to make the job a lot easier.
The Two Primary Types of Self-Tapping Screws
If you’ve already taken a trip to the hardware store, you might find yourself feeling confused about how many different options there are. Let’s break it down at a higher level before getting into the different subsets of self-tapping screws.
Thread-Tapping Screws. Thread-tapping screws don’t need a pre-drilled pilot hole. That said, you can still drill one to ensure that the fastener doesn’t damage the material but it isn’t necessarily required. The major downside to using this kind of screw is that the thread will get stripped out if you try to remove it.
Thread-Forming Screws. Unlike thread-tapping, this screw type definitely needs a pilot hole before you can proceed. The best way to identify thread-forming screws is the non-pointed end. They act in the same way, joining two materials together, but they tend to grip better than thread-tapping screws. Just be careful, because over-tightening can damage or even crack the material you’re working with.
Subsets of Self-Tapping Screws
Within those two major categories of self-tapping screws are a bunch of different subsets. If you’ve done even one DIY project, there’s a pretty good chance you’ve seen one or two of these before.
Bulge head. This screw has a head that is countersunk and has a flat top. The shape is on purpose because it evenly distributes the stress in a better way than a flat-head screw can. Generally speaking, you want to use the bulge head screw to attach plastic pieces to wood or metal studs.
Countersunk. If you need to have a finish that is flush or below the surface, this is the one to go with. Typically these are best for installations like drywall where the screw can’t be seen on the surface.
Socket head. Sometimes screws can get distorted and damaged when attempting to drive it in. This type of self-tapping screw is less likely to have that happen, mostly because of the drive shape.
Button/Dome head. You will pretty much only see this type of self-tapping screw in carpentry. The dome shape means that the head won’t countersink into the material.
Wafer head. This one has a flat top surface with a countersunk head. The design allows for the screw to sit flush in softer materials and wood.
Hex head. You will notice these pretty quickly because they have a hexagonal head. These are your heavy-duty screws where more strength is needed and countersinking isn’t required.
How to Determine the Right Size Self-Tapping Screw
One of the most common questions is, “how do I know what size self-tapping screw I need?” For the most part, trial and error is going to be the best bet. Start by thinking about what kind of material thickness you’re working with as well as the required finish.
Keep in mind that it’s easier to make the hole bigger using a larger screw than making a bigger hole smaller. What that means is you should always start smaller and work your way up to something bigger just to be safe and avoid doing irreparable damage to the workpiece.