In article ,
Ian Stirling wrote:
IMO, this figure is utterly irrelevant in most cases, it's hard to
get most types of screwdriver bit to exert enough force on the screw
to get it to fail this way.
And if you could, it's not relevant as by the time you've reached that
number, in nearly all cases the screw has gone too deep.

Yup. I often use my mains drill for screwdriving and it's got much more
torque than most cordless ones and no clutch.
A screw breaking is a rare event - they usually 'cam out' first with
Pozidriv

--
*Never put off until tomorrow what you can avoid altogether *

Dave Plowman London SW
To e-mail, change noise into sound.