eli5: Why are there different types of screwnail heads? Does it really affect the strength or integrity of the screw if the head is a Phillips, Robinson or standard?
In: Engineering
It does not affect the strength or integrity of the screw. The advantages is purely in the price of the screws and when installing the screw. A Robertson screw have the advantage over slotted screws that it have four surfaces instead of two so it can take twice the amount of force before deforming, and it is also self centering so that the screwdriver is always in the center where you get more torque. So you can apply much more torque to a Robertson screw then to a slotted screw of the same dimension. Phillips screws on the other hand is designed to prevent overtorquing. If you apply too much force to a Phillips head the screwdriver will push out instead of deforming the head of the screw or stretching the threads. This makes it much harder to damage the screw when fastening it then with the Robertson screw.
Modern screws use hex drives or torx. These are both six sided which allows you to apply even more torque then with the Robinson screw. The torx do allow you to use more force then a hex drive but is slightly more expensive to manufacture. Hex drives can also be driven at an angle with the correct tool.
So if you compare screws with older style heads to the ones with the newer style heads the older styles tends to use a larger head. This is because you need the larger head to get enough torque without damaging the screw. Whereas a newer style head can withstand a lot more torque with a smaller head. But once the screw is fastened there is no difference between the different styles.
Edit: Robinson -> Robertson
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