I've wondered the same thing Scott, I've seen ads over the years for 
McFeely's square drive screws but have never seen one and can't find any 
patent info for them.

Here is the patent for the Robertson. The Robertson's pocket has three wall 
angles in the socket. Perhaps the USA square drive socket is just a tapering 
straight wall?

http://www.datamp.org/patents/displayPatent.php?pn=116463&id=56456

Marv Paisner
Kootenay Lake, BC


-----Original Message----- 
From: Stager, Scott P.
Sent: Wednesday, February 20, 2019 8:41 AM
To: Listserv Oldtools
Subject: Re: [OldTools] Screw Head

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.

—Scott

On Feb 20, 2019, at 1:20 AM, Marvin Paisner 
mailto:paisners@s...>> wrote:

Robertson screws required one less step to manufacture as no slot had to be 
cut after the head was formed, the head shaping and tapering square socket 
were stamped on the same machine stroke.  The result being Robertson screws 
cost less to manufacture. However P.L. was able to sell them for more than a 
slot screw by demonstrating that the Robertson screw when set on the tip of 
his screwdriver would stay in place, even if you pointed the driver holding 
the screw to the ground.   Robertson was a good salesman.


---------------------------------------------------
Scott Stager
Columbia MO
573-474-5955 home
573-424-4764 cell
stagers@m...<mailto:stagers@m...>





------------------------------------------------------------------------
OldTools is a mailing list catering to the interests of hand tool
aficionados, both collectors and users, to discuss the history, usage,
value, location, availability, collectibility, and restoration of
traditional handtools, especially woodworking tools.

To change your subscription options:
https://oldtools.swingleydev.com/mailman/listinfo/oldtools

To read the FAQ:
https://swingleydev.com/archive/faq.html

OldTools archive: https://swingleydev.com/ot/

OldTools@s... 


---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus