![]() Instead, this design is provided with additional, much smaller, tapering notches in the centre of the drive, which give it its star-like appearance. In contrast to the classic cross-head drive, the flanks of the Pozidriv profile do not taper. One prominent variant is the Pozidriv system ("PZ"), which is used especially in woodworking ("Spax"). Today, there are several different types that can be tightened or loosened safely and easily with power tools and to high torques. The cross-head drive has been improved over time. The Phillips recess is easily confused with the Pozidriv system (see below).This design may compensate for misalignments between the fastener head and screwdriver, but when the fastener is tightened or loosened, an axial force is generated at the same time, which can force the tool out of the profile ( "cam-out effect"). The profile tapers to a point: the sides of the screwdriver taper and are not parallel to each other.Due to these positive locking properties, the crosshead screw can also be tightened or loosened by machines.Thanks to the improved positive locking characteristics, the danger of slipping off sideways is significantly lower than with the slotted screw. But that is not all: the design makes it easier to apply the screwdriver. The cross-slot drive is self-centring, which stops the screw wobbling.He sold his patent to the Phillips Screws company, which is why the cross-slotted screw system is still called Phillips recess, Phillips or just PH. Thompson invented the cross-slotted screw, which effectively eliminated the disadvantages mentioned above. once you have slipped, you have to pay more attention to reapplying the screwdriver, which costs time and nerves. In addition, there is only one position to apply the tool, i.e. The risk of the tool slipping is high.Insufficient centring, however, means there is a growing danger that the screw will wobble when it is screwed in. Since the slot is quite wide, it is hard to guarantee that the screwdriver is really located in the centre.The fact that many other profiles have superseded it today is mainly due to two major problems of this type of drive: Right up to the 1930s, it was used more widely than any other type. The flat-slotted screw head is the most "traditional" kind. ![]()
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