On Jul 18, 9:16*am, Jim Yanik wrote:
" wrote innews
On Sun, 17 Jul 2011 18:05:14 -0500, Jim Yanik
wrote:
Phillips screws main problem is camout.

Since they were designed to cam out (here we go again), that's not
surprising.

Do you REALLY believe Phillips was "designed" to camout?
what gave you that idea?

I don't know whether it's really true or not, but that seems to be the
accepted story.

From http://en.wikipedia.org/wiki/Phillip...river#Phillips

Phillips
Phillips drive tool and fastener sizes[3] Tool size Fastener size
0 0–1
1 2–4
2 5–9
3 10–16
4 18–24
Created by Henry F. Phillips, the Phillips screw drive was purposely
designed to cam out when the screw stalled, to prevent the fastener
damaging the work or the head, instead damaging the driver. This was
caused by the relative difficulty in building torque limiting into the
early drivers.

The American Screw Company was responsible for devising a means of
manufacturing the screw, and successfully patented and licensed their
method; other screw makers of the 1930s dismissed the Phillips concept
because it calls for a relatively complex recessed socket shape in the
head of the screw — as distinct from the simple milled slot of a
slotted type screw.

There are five relatively common (and two rather uncommon) Phillips
drive sizes that are different from the screw size; they are
designated 000, 00, 0, 1, 2, 3, and 4 (increasing in size).[3][5]