Re: Which screw driver head is best and why? -- slotted, + philips or

 Hi Jim.

Ideally, you'd like your "driver" to have as much surface area as 
possible with the "screw".  This means you'd like to have as deep
a slot/groove/etc on the "screw" as possible, with lots of length
to it (why you get a slot that runs all the way along the head of
the screw).  

Let me start by saying that the ultimate answer involves (of all 
things) money.  It's cheapest to make slot head or phillips head 
screws, and more expensive to make hex or square drive recessed
screws.

If you're tightening a slot or phillips screw, and it stops turning,
you have to apply more torque, while simultaneously  pushing the 
driver into the screw.  If you don't push hard enough while you're
turning, your torque will cause the driver to push back, thereby
starting the process of stripping the screw head.  A solution to 
this problem is the hex or square drive screws.  You don't have to 
exert a forward force on them to tighten, so they don't strip so
readily.

So, if you don'y mind spending a little more on your screws, the 
hex and square cap ones generally strip less often.

Does this answer your question?
email me if you'd like to discuss it more.

Best Regards,
Mike Weibel