When a Phillips is not a Phillips!

Step 8 Phillips Drive

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. The Phillips driver has four simple slots cut out of it, each slot is the result of two machining processes at right angles. The result of this process is that the arms of the cross are tapered and has slightly rounded corners in the tool recess. Phillips is designed so that when excess torque is applied it will camout rather than ream the recess and destroy the bit. The driver has a 57 degree point with a blunt tip, tapered wings. Identified in ANSI standards as type I.

Advantages & Disadvantages of Phillips

In all cross drive systems the driver will self-align with the fastener. The tapered design that allows camout can become a problem as the tooling that forges the recess in the head of the screws begins to show signs of wear. The recess becomes more and more shallow, which means the driver will bottomout too soon and will cause the driver to camout early. Another problem is even though the ease to insert, Phillips screws can be tough to get back out. The main disadvantage is the screwdriver pops out too readily, stripping the screw, gouging the work, and in general transferring all the problems that were formerly with the Slot design. Consumers are likely to think that any screw head with a cross drive recess is a Phillips, which can lead to problems.