Self-tapping screws for aluminum have the benefit of not requiring pre-drilling and may be quickly removed without harming the metal. They may be reused in the same material as well. However, self-tapping screws for wood are not reusable and must be drilled out.
Drilling a pilot hole through the material before using self-tapping screws is recommended, but not required. This assures that the screw will go in smoothly and accurately. When drilling the pilot hole, use a smaller drill bit than the self-tapping screw. This will prevent tearing out too much of the surrounding wood while still providing enough space for the screw to enter.
Self-tapping screws are commonly used for framing buildings because they can be used with drywall or other wall materials without removing the screw after it has been inserted. The screw creates its own pilot hole when it is driven into the material.
The advantage of self-tapping screws is that they don't need any special treatment before being installed. They also don't move around after they're placed under load, which makes them good choices for mounting heavy items such as shelves or cabinets to walls.
Disadvantages of self-tapping screws are their cost and lack of availability for some materials. Not all types of wood can be easily penetrated by a sharp screw, so these screws are not suitable for every project.
If you plan to use self-tapping screws on a regular basis, consider buying a low-cost set of drivers for your hand tool. This will make installing the screws easier and faster. Self-driving screws are also available if you want to avoid using power tools entirely.
Self-drilling screws do not require a pilot hole, although they may also be tapped. Self-tapping screws tap their own threads, however they cannot drill through metal and must be accompanied by a pilot hole. These screws are not interchangeable, and mixing up the two can cause many headaches or possible failures in the field. Drilling a threadless hole using a power driver is very difficult if not impossible.
The best way to tell whether a screw is self-drilling or not is to look at the head of the screw. If the head is flat, it means that it will require pre-drilling of a hole before it can be screwed into something. Flat-headed screws are only useful for general purpose applications where you need to fasten one piece of material to another. They cannot be used to drive wood beams into concrete foundations because they would not be able to cut into the material.
Tapered screws have a slightly tapered tip which allows them to be turned easily with a standard hand screwdriver. This makes them ideal for use in small spaces or when you need multiple holes drilled in one go. Taper-headed screws can be used in almost any application where a standard screw would be suitable. They are not designed to be driven into concrete, so they won't last forever if used in heavy duty situations.
Self-tapping screws use a sharp blade on the end of the screw that cuts its own thread as it drives itself into wood.
If the tip is flat, it is thread-rolling, which implies it is rolling or extruding threads with no space between the screw and the material. The primary distinction between self-tapping and self-drilling screws is that self-tapping screws cannot penetrate metal without a pilot hole, which must be pre-drilled or pre-punched. Self-drilling screws can drill their own holes through material without prior preparation.
The most common application for self-tapping screws is to drive them into wood pulp board (a type of cardboard) to make shelves. The screw creates a decorative hole when it is pulled out of the board. This is called dry tapping because there is no liquid content in the board to help the screw create its own cutting edge while driving it home. Dry tapping is easier to do with thicker boards so they will have more strength to resist being driven completely through.
Dry tapping is done by hand or machine. Hand tapping uses a hammer and chisel to tap the screw into the wood over time. This is a slow process but it gives you complete control over how deep the screw goes into the wood and also what shape its head will be when it comes out the other side. Hand tappers usually strike the screw on one side only of the head to avoid breaking off too much material. This leaves a rough surface that can be sanded down later if needed.
Machine tapping uses a powered screwdriver-like device instead of hand tools.