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Self Tapping Screws Guide

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Self tapping screws are possibly the most popular form of screw fastening, widely used in all manner of applications. People ask many questions about self tapping screws so this guide is intended to answer some of the common queries.

What are Self Tapping Screws?

Self-tapping screws are designed to cut their own screw threads as they are screwed into a material. There is no need to create a screw thread in a pre-drilled hole as the self-tapping screw does the work as it is screwed in.

Self tapping screws are generally made from carbon steel or stainless steel in a variety of screw types such as pan head and countersunk. There are also specialist types such as self tapping screws specifically designed for use in concrete, brick or mortar.

self tapping screws
Common Self Tapping Screws

 

What is the Difference Between a Self Tapping Screw and a Self Drilling Screw?

People often ask about the differences between self-tapping and self-drilling screws. Self-tapping screws create their own threads, but aren’t generally designed to create their own holes. However, when used with certain soft materials such as wood and some plastics, self-tapping screws will successfully cut their own holes as well as tapping the required thread.

hex head self drilling screw
Self Drilling Screw

 Self-drilling screws are distinguished by having an integrated drill bit at the tip of the screw.

Types of Self Tapping Screws

Broadly speaking, there are two primary types of self tapping screws, thread-forming and thread-cutting.

Thread forming self tapping screws have a blunt tip. They require a pilot hole that’s slightly smaller in diameter than the screw shaft diameter. Thread forming screws are typically used to tightly join plastic materials together. Care should be taken not to overtighten as this can cause damage.

Thread cutting self tapping screws have pointed tips. Generally, they don’t require a pilot hole to be drilled, although this can often be a good idea.

Self-tapping screws with a variety of screw-head types are widely available including countersunk, button-head, pan-head, hex-head and many others. The selected self-tapping screw type must be appropriate for the fastening task.

Self Tapping Concrete and Masonry Screws

Self tapping concrete and masonry screws are an excellent example of the practical application of self tapping screw technology. Extensively used to affix all manner of items to brickwork, blockwork, concrete and masonry, self-tapping masonry screws provide an easy-to-use fastening solution for everything from security ground anchors to washing lines.

atlas concrete bolts with substrates
Atlas Bolts with Substrates

Using self tapping masonry screws simply requires that a pilot hole is drilled in the substrate that’s smaller than the diameter of the screw. This can generally be achieved in stone, brick and blockwork using a hammer drill. The self-tapping masonry screw will then cut its own thread as its screwed in.

Self Tapping Screws for Plastic

Plastics can be very rigid and therefore susceptible to splitting and cracking making it important to drill a pilot hole of the required diameter in the plastic substrate for the self tapping screw. While standard self tapping screws are suitable for most plastics there are specially designed self-tapping screws for plastics which have more pronounced, sharper threads that create a more robust fastening that is less susceptible to being pulled out and thread-stripping.

Self Tapping Screws for Wood

Using self-tapping screws for fastening to softer woods doesn’t require the drilling of pilot holes. But when using self-tapping screws with harder woods drilling pilot holes, smaller in diameter than the screw shaft, is always recommended. Its important to consider the screw material as moisture in the wood can cause corrosion. So stainless steel or corrosion resistant self tapping screws are recommended.

Self Tapping Screws for Metal

When using self tapping screws in metal pre-drilled pilot holes are always needed. The hardness of the metal substrate must be considered when using self tapping screws as the self-tapping screw might be softer than the metal material into which it is being screwed. This would damage the self tapping screw and result in an insecure fixing.

How to Use Self Tapping Screws

Here are some basic pointers to help you successfully use self tapping screws.

Always select the correct type of self tapping screw for the task. For example, if the need is to attach something to stone or concrete then self tapping masonry screws are needed. And if the need is to join two pieces of plastic then you should use appropriate self tapping screws for plastic.

Where necessary, drill pilot holes of the right diameter. As noted, some materials will always require that pilot holes are drilled for self topping screws. Always make certain not to drill holes larger than the required diameter.

Ensure correct screw alignment. When inserting and tightening a self tapping screw its important to ensure correct alignment. Make certain the self-tapping screw is perpendicular to the pilot hole before being screwed in and tightened.

Self Tapping Screws FAQs?

Here are just a handful of commonly asked questions about self tapping screws.

  • How to remove self tapping screws.
    • Self tapping screws are generally easy to remove using the right tool or screwdriver.
  • Can you reuse a self tapping screw in the same hole?
    • Generally, self tapping screws can be successfully reused in the same hole. But in some circumstances the substrate can be damaged when the screw is removed and this would require the use of a new self-tapping screw with a larger diameter to ensure a secure fixing.
  • How can you tell if a screw is self tapping?
    • Self tapping screws have pointed tips designed to be inserted into pilot holes or softer substrates. Self-drilling screws are distinguished by having an effective drill bit at the tip of the screw.
  • Can you use self-tapping screws in concrete?

If you have any questions regarding secure fastenings or self tapping screws and bolts remember that we are here to help. Give us a call on 01273 475500 and we’ll provide you with free, expert advice.

This message was added on Thursday 1st July 2021

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