Why are there Different Types of Screws used in different construction purposes?

Why are there different types of screws?

Different types of screws used in construction purpose are listed below

  • Slotted – Easy to manufacture. You can just cut a slot across the top of a screw. You can tighten one of these really well. The biggest problem is that there is nothing to keep the screw driver centered so it’s easy to slip to one side off the screw head and this problem is amplified when using a powered driver. This makes it easy to damage the surface next to the screw.
  • Phillips – Solves the centering problem by using a stamped cross pattern in the head with an angled bottom. The head is designed so that the driver cams out when a certain level of torque is reached thereby eliminating over tightening of the screw [important to aircraft and other industries using sheet metal avoiding the screw tearing through the hole while attacking the sheet].
  • Pozi – A variation of the Phillips head designed to not cam out thereby increasing the torque that can be applied to the screw.
  • Robertson – Also solves the centering problem by using a square hole instead of the Phillips/Pozi cross design. The hole bottom is flat so there isn’t an intention to cam out under torque.

Why are there different types of screws

  • Allen/Hex – Uses a hex hole instead of a square or cross pattern. This has an advantage since drivers are available with a ball-shaped hex head. Using this type of driver allows the screw head to be turned by a driver that approaches from an angle making it the only screw that can be turned by a tool coming from an angle.
  • Torx – Uses a six-sided star shaped hole pattern also called a star drive. The bottom of the hole is flat like the Robertson and the Allen and fairly deep. The drivers I’ve used have a slight taper which holds the screw onto the driver fairly well making it easier to drive in areas where there is no room to hold the screw with a second hand while getting it started.
  • Security variations – Robertson, Pozi and Torx screw heads offer a feature that includes a center pin preventing a driver from entering unless the driver has a center hole to accept the pin. These are termed tamper resistant since the drivers needed are far less common than the normal drivers.

These are the different types of screws that we normally use in construction purposes.

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