Woodscrews are available in a range of materials such as carbon steel, hardened steel, zinc, stainless steel and solid brass. Brass is usually chosen for its appearance when combined with brass ironmongery such as hinges and door handles. Stainless steel is ideal for areas exposed to moisture, and carbon and hardened steel can be fitted without needing pre-drilled holes. In addition, all wood screw materials have high levels of corrosion resistance. They are available in gauge sizes ranging from 3 to 8mm and lengths from 12 to 300mm. where T D {\displaystyle TD} is the tap drill size, M D {\displaystyle MD} is the major diameter of the tap (e.g., ⅜ inch for a ⅜"-16 tap), and N {\displaystyle N} is the thread pitch (16 in the case of a ⅜"-16 tap). For a ⅜"-16 tap, the above formula would produce 5⁄ 16 as a result, which is the correct tap drill diameter for a ⅜"-16 tap. The above formula ultimately results in an approximate 75 percent thread. In general, if the letter "B" is in a screw's designation, such as Type AB or B, it has spaced threads. If the "B" is absent, as in Type F, the screw has machine screw threads. There are two exceptions: Although considered obsolete but still available today, Type A has spaced threads. And metallic drive screws, denoted Type U, have spaced spiral threads.

Tap in a wrench for creating female threads (left), and die in a wrench for creating male threads (right).Locate Utilities - Ensure there are no electrical, plumbing, or gas lines in the vicinity of your drilling and installation area. To help with this alignment task, several kinds of jigs and fixtures can be used to provide the correct geometry (i.e., accurate coaxiality with the hole) without having to use freehand skill to approximate it: Self-tapping and drilling screws are available in steel, carbon steel, and stainless steel. Gauge sizes range from 3.5 to 6.3mm, and lengths range from 12 to 120mm. If you encounter significant resistance, you can tap the screw gently with a hammer to help it get started.

Aluminium has many positive characteristics that make it easy to work with. When using self-tapping screws on aluminium, choose a self-tapping screw with a drill-like point and sharp cutting blade threads that extend down the whole length of the screw. These self-tapping screws are designed to keep thin metal from denting. Tapcon Countersunk Head Screws have many advantages - they can be installed close to edges, they are removable and adjustable, fire resistant and can replace small diameter expansion anchors, plugs and screws in light to medium-duty applications. Solid dies cut a nominal thread form and depth, whose accuracy is subject to the precision the die was made with, and the effects of wear. Adjustable dies can be slightly compressed or expanded to provide some compensation for wear, or to achieve different classes of thread fit (class A, B and more rarely, C). Adjustable taps also exist but are not common. These have a tip that is split through the flutes and an axial screw which forces the cutting edges slightly apart.

One final design that is very common is the drywall screw. Available in sharp point and self drilling styles, the sharp point is used with wood and light gauge steel studs, and the self drilling style is designed for heavy gauge steel studs. The unique bugle head is self countersinking, resists tearing the drywall paper surface and is said not to damage the gypsum core.

For a long time this seemed to me like an esoteric and scary task, but when I had to do it, I discovered that it is not difficult at all. It requires a bit of time, a bit of fiddling, and a tap & die set, but is well within anyone's ability who has full use of their hands. I do not even own this tap & die set, I borrowed it from my cousin! You may have a cousin with a tap & die set too. Many people do.Coach screws: these are driven into materials using a spanner through a square or hexagonal head. They provide robust and heavy-duty fixing. Some self-tapping screws such as the Tek screw brand, are also self-drilling, which means that in addition to the thread-forming section there is also a fluted tip much like the tip of a center drill. These screws combine hole drilling, threading and fastener installation into one driving motion (instead of separate drilling, tapping, and installing motions); they are thus very efficient in a variety of hard-substrate applications, from assembly lines to roofing. [4] [5] Some types incorporate a sealing washer, for fastening roofing sheets to purlins. [6] Sheet metal screw [ edit ]