RickMerrill (Rick0.merrill@gmail.NOSPAM.com) wrote:
> cliff wright wrote:

> > Richard Bonner wrote:
> >> ***   Even the right tool will not work if the screw heads chew easily.
> >> Soft-metal hardware is too common today, and since most of these screw
> >> heads tend to be Phillips, the problem is even worse. I hate Phillips
> >> screws! They should all be Robertson!
> >>
> >>          Richard Bonner

> > ...what are "ROBERTSON" screw heads? Are they perhaps those rather
> > nice square drive ones that I've used with wood screws?
> > 
> > Cliff Wright.

> ROBERTSON screw heads are several, but basicly LOOK like a Phillips BUT 
> the slots are full depth. It is said that H. Ford had tests done with
> both phillips AND Robertson heads and they choose the phillips because
> the assemblyman could not over-tighten the phillips: the screwdriver
> would pop out.  But with the robertson the screw could easily be
> over tightened.  

***   I believe you may be thinking of Torx screws. 

   Robertson screw and bolt heads have a square, deep, tapered socket. The
drivers have a tapered tip that slopes at a different rate, so the drivers
will jam themselves on to the screw heads. One can hold a driver and screw
with the tip down without the screw dropping off. 

http://canadianhistory.suite101.com/article.cfm/peter_lymburner_robertsons_screwdriver

         Richard Bonner
http://www.chebucto.ca/~ak621/DOS/