[R-390] bristol wrenches

[2002tii]

>How do the mechanical features of Bristol fasteners stand up against Torx
>fasteners?  It seems to me that Torx came about for similar reasons some
>50 years after Bristol...

They are very similar.  With careful selection for size, a Torx tool 
can be used with good success on a Bristol fastener (the cheap 
Chinese Torx bits commonly found in dollar stores, Harbor Freight, 
etc., which are often slightly undersize, are particularly useful for 
this if you don't have a proper Bristol tool).  Torx tips and 
recesses are easier to make using modern methods, while the Bristol 
system will arguably permit somewhat greater torque to be applied 
(all else equal).  But yes, they are two very similar attempts to 
solve the same problem, and both did it quite successfully (from an 
engineering standpoint -- Torx has done much better in the marketplace).

Best regards,

Don