Somewhere in thisa gruop there was a discussion of these. IIRC it's
called a Torx PLus or something like that. Maybe not available in
your local grocelly/general shop, but a well supplied tools or
electronics vendor might have them...
http://en.wikipedia.org/wiki/Torx at the end...
From Wikipedia, the free encyclopedia
TORX screw head design
TORX, developed by Textron Fastening Systems (formerly Camcar
Textron), is the trademark for a type of screw head characterized by
a 6-point star-shaped pattern (in the same way that slotted heads,
Phillips, Allen, and Robertson have flat, ×-shaped, hexagonal, and
square tips, respectively). People unfamiliar with the trademark
generally use the term star, as in "star screwdriver" or "star
bits." The generic name is hexalobular internal driving feature and
is standardised by the International Organization for
Standardization as ISO 10664.
By design, TORX head screws resist cam-out better than Phillips head
or slot head screws. Where Phillips heads were designed to cause the
driver to cam out, to prevent over-tightening, TORX heads were
designed to prevent it. The reason for this was the development of
better torque-limiting automatic screwdrivers for use in factories.
Rather than relying on the tool slipping out of the screw head when
a torque level is reached, and thereby risking damage to the driver
tip, screw head and workpiece, the drivers were designed to
consistently achieve a desired torque. Textron claims this can
increase tool bit life by an order of magnitude, or more.
TORX screws are commonly found on automobiles, computer systems and
consumer electronics, but are also becoming increasingly popular in
construction. Do-it-yourself mechanics will often remove the TORX
screws on a vehicle and replace them with more common screws and
bolts such as hex head bolts, because they believe it is easier to
carry an adjustable wrench to fit many different sizes of hex heads,
rather than carrying several different sizes of TORX screwdrivers or
bits. [edit]
Sizing
TORX head sizes are described using the capital letter "T", followed
by a number. A smaller number corresponds to a smaller
point-to-point dimension of the screw head. Common sizes include T5,
T10, T15 and T25, although they reach as high as T100. Only the
proper driver can drive a specific head size without risking the
ruin of the driver or screw. The same series of TORX drivers is used
to drive SAE, metric and other thread system fasteners, reducing the
number of bit sizes required. [edit]
Variants
Security TORX driver
A version known as Security TORX or Tamper Resistant TORX (often
shortened by Torx TR) contains a post in the center of the head that
prevents a standard TORX driver from being inserted.
An external TORX version exists, where the screw head has the shape
of a TORX screwdriver bit, and a special TORX socket is used to
drive it. These are found primarily on automobile engines.
A TORX variant, TORX PLUS, is designed to allow greater torque, and
to minimize wear. Currently, TORX PLUS heads and drivers are
patented, slowing adoption in the marketplace. Standard TORX drivers
can be used to drive TORX PLUS screws, but TORX PLUS drivers will
not fit standard TORX screws. There is also a tamper resistant
version of TORX PLUS, having five lobes and solid post in the center.
TORX, TORX PLUS and Camcar are registered trademarks of Textron, Inc.
===========================================================
