The development of modern hand and power tools has made it much easier to drive fasteners into their slots with speed and precision. Today, automatic machines remove even the disorientation that comes with fastening operations but still, it takes skill, patience and many hours of practice to complete an operation successfully without overdriving a screw. Overdriven fasteners can affect the shear capacity of the wall by up to 22%, so it’s important to avoid overdriving by implementing these few simple tips.
Use Your Driver’s Torque Control
Every drill/driver comes with an adjustable collar, located behind the chuck, called a slip clutch. The slip clutch controls the amount of torque transferred to the head of the fastener – the higher the number, the more torque is delivered. If the force required to drive in the screw exceeds the amount set by the slip-clutch, it will disengage or ‘slip,’ at which point the chuck will stop turning even while the motor is still running. Determining the correct slip clutch setting for a particular fastener and the relevant material is a skill that takes time and practice. The general rule of thumb is that softwoods require little torque (a lower setting) while hardwoods or metals require a lot more (a higher setting). Once you master this skill, it’s an ideal tool for driving screws to the correct depth without overdriving them.
Use Self-Centering Bits for Precision
Achieving perfectly aligned slots for your fasteners can be tricky, particularly if the installation requires millimetre accuracy. Get it wrong, and you risk overdriving the fastener at a skewed angle, causing all sorts of problems. So how do the professionals get it right? They use a tool called a self-centering bit. It’s a simple device that uses a tapered point to align the drill bit, which then protrudes through the centre once the operator begins drilling. Self-centering bits also include depth stops to avoid overdriving, a particularly useful feature for driving longer threads.
Drill a Pilot Hole
Pilot holes are small-diameter holes bored into the base of the board, acting as a guide or providing clearance for a self-threading fastener. Without a pilot hole, the fastener can generate outward pressure, causing the material to split, or the core of the screw may bind and break. Pilot holes are particularly important when driving brass fasteners as they’re softer and more likely to snap under pressure.
Practice Makes Perfect
As with any new skill, the only way to become a master is to put in the hours. Yes, you’ll struggle in the beginning, but after a little trial and error, you’ll begin to understand the fundamentals and each attempt will be easier and more accurate.
For any assistance (or motivation), don’t hesitate to contact the team here at Bearing Centre and keep in mind that we stock a world-class supply of fasteners, as well as a number of related hand tools and power tools.