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TORX, developed by Camcar LLC of Acument Global Technologies (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, hex socket, and Robertson have linear, cruciform, 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. TORX is frequently styled Torx despite the official all-caps trademark
styling.
By design, TORX head screws resist cam-out better than Phillips head or slot head (flathead) 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 achieve a desired torque consistently. Camcar LLC claims this can increase
tool bit life by ten times or more.
- Wikipedia
Here is their main Torx
webpage.
This table presents the most common sizes.
|
T-1 |
0.033 |
0.024 |
|
T-2 |
0.037 |
0.027 |
|
T-3 |
0.044 |
0.032 |
|
T-4 |
0.051 |
0.036 |
|
T-5 |
0.055 |
0.040 |
|
T-6 |
0.066 |
0.048 |
|
T-7 |
0.077 |
0.056 |
|
T-8 |
0.090 |
0.065 |
|
T-9 |
0.097 |
0.070 |
|
T-10 |
0.107 |
0.077 |
|
T-15 |
0.128 |
0.092 |
|
T-20 |
0.151 |
0.109 |
|
T-25 |
0.173 |
0.124 |
|
T-27 |
0.195 |
0.140 |
|
T-30 |
0.216 |
0.155 |
|
T-40 |
0.260 |
0.187 |
|
T-45 |
0.306 |
0.218 |
|
T-50 |
0.346 |
0.242 |
|
T-55 |
0.440 |
0.312 |
|
T-60 |
0.520 |
0.372 |
|
T-70 |
0.610 |
0.435 |
|
T-80 |
0.689 |
0.497 |
|
T-90 |
0.782 |
0.558 |
|
T-100 |
0.870 |
0.620 |
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