Torx Or Hex Head ?

Every tool box that I own has some of those bolts in the bottom. Harrier engine bolts if my memory serves me.

 

Keith, I agree but the driving point is important to the likelihood of spinning the tool, if the driving point was on a radius of say 4mm rather than 8mm then the point load to achieve the same torque setting is significantly higher. The benefit of torx is mainly that the angle of the driving load is closer to 90 degrees but that is offset to some degree by the smaller diameter driving radius. Probably more important when undoing stuff than tightening it up however

 

I think the driving load angle is only 15 degrees

 

Fully agree with the above. Like for like, the force at the 4mm rad is twice the force at 8mm rad for the same torque. This very well explains why button-head hex-socket screws are rightly reviled. Their hex sockets are readily deformed because of their smaller hex 'radius' (+shallow insertion, which increases interface pressure as well!) and subsequently higher force required on the metal for tightening/loosening.
A very simple but conceptually hard topic.....

 

For metric socket head or metric Torx head, I always make sure that I have my Imperial keys and bits handy, because I find metric to metric aren't always tight enough in the sockets....Imperial sets have a greater range of bit sizes.

Now I have the Harley, I have socket head; torx and hex head bolts and screws to deal with.......several not only have a socket head indent but they also have a 12 point outside face to take a conventional socket.

Gets confusing, when you are used to picking up the right tool for the job, just by looking at the bolt.

 

Bondhus hex keys Al. They’re brilliant and very resilient, mine have served me well for years and still going strong.

Also worth mentioning that not all bolts are made to the same standards.

unbrako and snap-on worked very closely together due in part to US government contracts, so they’re pretty much toleranced around each other.

unless you’re looking at NAS or similar levels of manufacturing tolerances, any off the shelf bolt is going to be a case of pot luck with regards tool fit.

 

I use PB Baumann now PB swiss for allen keys and torx.

Superb fit and long lasting. The edges don't round off and keep their shape.

https://www.pbswisstools.co.uk/catalog/PB_Swiss_Tools/PB_212_LH.html