On Wed, Feb 20, 2019 at 8:52 AM Stager, Scott P. 
wrote:

> Can someone support a refute a notion I have in my that the actual
> Robertson screw socket is in fact not identical to the square drive screw
> sockets we have available to day in the USA?  Somewhere in the dusty
> corners of my brain I have a recollection of reading a discussion of this
> that pointed out that the USA square drive socket is less precise than the
> actual Robertson.  Thus, the USA square might not actually “stick” on the
> end of the driver.
>
>
I have heard that, probably here, but don't have facts to support it.  I
suspect our Canadian correspondents know this answer, with backing data.  I
think the answer is the taper to the socket is slightly different.
-- 
Kirk Eppler in HMB, CA looking for shop time