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What are self-drilling screw tips?

 
         
  Self-drilling screw tip  

A self-drilling tip effectively drills its own pilot hole through the material as the screw is being driven in.

 
         
  Sheet metal screw  

It has a cutting blade which sends the waste material back up the body of the screw and out of the hole.

 
         
     

Self-drilling tip with wings

 
  Self drilling tip with wings  

Some self-drilling tips have wings above the drill tip. These wings drill a clearance hole for the screw as it’s being driven in.

 
         
  Sheet metal self-drilling tip with wings screw  

A screw with this type of tip is suitable for use in thicker materials, and is designed specifically for use when joining wood to metal.

 
         
  Self-drilling tip with wings screw being driven into material  

How does it work?

As the screw is being driven in, the wings enlarge the hole in the material created by the drill tip.

 

The threaded part of the screw can now pass through the hole without the timber ‘jacking’ (pulling away from the metal).

 
         
  Screw with self-drilling tip with wings with the wings fallen off  

When the wings come into contact with the metal, they break off, allowing the threads to fully engage with the metal.

 
       Wonkee Donkee says "Straight from the donkey’s mouth! Screws with self-drilling tips may not be suitable for use in overhead applications. This is because they need quite a lot of pressure to get them started, and this is often easier to do when pushing down on the tool from above"  
         
     

Advantages

 

Disadvantages

  • No need for a pre-drilled hole of any kind. As a result, you don’t need to worry about drilling the correct size pilot hole – the drill bit does that for you!

  • Manufacturers claim that self-drilling screws increase productivity as they reduce the number of steps needed to join materials together

  • They also claim that self-drilling tips allow the material to be clamped together more tightly.

  • Usually have a higher heat tolerance compared with non-self-drilling screws. This means that they can join metal to metal at higher speeds

  • Tend to be stronger than those without self-drilling tips. This is because the tip and sometimes even the whole screw is made out of drill steel.

  • Available for use in various materials including wood, metal and plastic

 

  • May be more expensive to purchase and less widely available

  • As they are a relatively new technology, not all of the disadvantages are known yet

 
         
  Wonkee Donkee says "Straight from the donkey’s mouth! Screws with self-drilling tips are often referred to as Tek screws. However, Tek is a brand name and should not be used as a generic term for these types of screws"