On 08/17/06 03:40 pm z wrote:

which screw head is better? for a non-slip power driver's use. And what
type for shear-resistance? outdoor/indoor etc?

roberts is much more secure in terms of not slipping out and shredding
the head, much like an allen head, but the phillips has the advantage
conversely, in that it can drive the screw when it's not absolutely
colinear, coming in at an angle, as long as you don't overdo it and let
it slip. there are those variants of the phillips which have different
shape tapers which have less of a problem, whose name I forget.

Pozidriv

Perce