Why torx bolts are better than Hex bolts

It goes without saying that most things evolve over time, and bolts are no exception.

The 6 point hex bolt design we know, see and use on a daily basis was standardized in the United states in the 19th century.

The Torx bolt design was invented and patented by Camcar Textron in 1967.

So we know Torx is newer, had the hindsight to see the pitfalls of the hex design, but why is it specifically better?

Anybody who has worked with Allen keys knows just how easy an Allen hex hole strips out. What many people don’t think about is that a 6 point hex bolt is just the inverse external version of an Allen hex hole.

As illustrated below, the visual explanation for internal or external is the same. You can view the picture as an internal bolt, or as an external bolt with a socket around it.

The drive angle is the primary driving force behind why a Torx bolt is able to handle more torque before stripping. A hex bolt relies on a 60 degree angle while the Torx bit relies on a 15 degree angle.

The significantly smaller drive angle forms a much tighter tolerance, which better distributes the concentration of force to all points and therefore allows for much higher torque values before rounding out.


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