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Comment by nkurz | Hacker News Reader

I thought best part of the article was the explanation that Phillips head screws were in fact designed to be difficult to fully tighten:

The Phillips system was invented for use in assembling aluminum aircraft, with the object of preventing assemblers from tightening screws so tightly that the aluminum threads strip. The driver will cam out before that happens. ... Phillips is designed so that when excess torque is applied it will camout rather than ream the recess and destroy the bit.

It's not a bug that the screwdriver keeps slipping out when you are struggling to make that last quarter turn at an awkward angle, it's a feature!

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This is sort of like the QWERTY keyboard layout: originally designed to slow down typists so they wouldn't type faster than the typewriters of the day could handle. That constraint is now long obsolete, yet we're still stuck with it.

The application that really showcases what TFA calls the "camout" feature is drywall. A drywall installer will keep the screwgun turning, and every time he punches the gun into the drywall, a new screw is pushed off the belt. The screw is driven until the gun hits its stop (a sliding mechanism that controls how close the gun can get to the drywall) and the screw naturally slips out when it's at the proper depth. This is important because drywall is quite fragile and otherwise it would be easy to drive a screw too far.

> This is sort of like the QWERTY keyboard layout: originally designed to slow down typists so they wouldn't type faster than the typewriters of the day could handle. That constraint is now long obsolete, yet we're still stuck with it.

Except that wasn't really the reason. The reason was to prevent the keys from jamming (by locating common letters and sequences of letters away from each other); the fact that it tended to slow typists down was only a side-effect.

Absolutely; I've also worked with screws that were, as far I as I could understand, purposely made of less rugged metal to ensure that when they were tightened against the object they were meant to fasten (made of plastic), they would strip before damaging it.

Still sucks to accidentally strip a screw that really should be that tight!

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