slipping screwdriver

[Steveb64]

I think you're talking about 'Phillips' and 'Posidrive'?

An explanation - copied from a fasteners FAQ...

Cross head screws. These come in two varieties, Phillips and Posidrive.
The differences lie in the way that the drivers are machined. The
Phillips driver has 4 simple slots cut out of it, whereas in the case of
the Posidrive each slot is the result of two machining processes at
right angles. The result of this is that the arms of the cross are
parallel sided in the case of Posidrive, and tapered in the case of
Phillips. Posidrive is less likely to slip out because of this, but as
there are small protrusions left in the bottoms of the grooves a
posidrive driver will not fit a Phillips screw correctly. Both varieties
come in a range of sizes. The case screws on Japanese bikes are
universally Phillips.

If you need to see a picture, try this link: http://www.justbrits.com/pozi/pozidriv.html

[themess]

I think that Phillips was designed to slip out to prevent over-torqueing.

[trippivot]

American phillips are designed to "cam out" especially the #2 size
lots of guys try to use a #2 on what needs to be a bigger #3 also
get a J.I.S. tip tool japanese industrial standard or
swap to allen head and get some ball end tips you'll love it!!

less than 90 inch pound torque on a 6X1

[sschering]

You can get a set of JIS screwdrivers from McMasterCarr
http://www.mcmaster.com/#jis-(japanese-industrial-standard)-screwdrivers/=2rxnz7

order item #53325A41
It's a set of 4 drivers size #1,#2,#3 and #4

They really do work and don't cam out.

They are the only place I've found that has #3 and #4 available.

Sorry about the blast from the past..