History of screws

[andyandlyn]

Anyone know the history surrounding cross head and flat screws? I take it for granted that they exist but never know the benefits behind each one! So... when is a cross headed screw better than a flat headed one??

[rekstout]

The cross-head -aka Phillips - screw was invented as it is better suited to powered screwdriving, the nature of the cross means that a screwdriver bit will always be centered correctly, if the bit were offset then the screw would wobble as it was driven in and this couldn't be corrected manually if the screwdriver was powered/automated such as one on a production line.

I don't know why we still have both types but I would hazard a guess that slot-head screws are cheaper to manufacture or possibly stronge in some way..