On 12/13/2011 1:19 PM, Ron Nossaman wrote: > On 12/13/2011 12:23 PM, Delwin D Fandrich wrote: >> If memory serves--and it may not--I think Robertson's square-drive screws >> was in use before the Phillips-type screw came along. I seem to recall >> reading somewhere that Henry used square-drive screws in his Model T. The >> Phillips screw wasn't invented until 1930 something. With the >> metallurgy of >> the day the Phillips-type screw could take more torque. > > I've read that the Phillips was designed to cam out before it reached > damaging torque levels, like the hex drive or Robertson. I meant, like the hex or Robertson could produce. >Kimball refined > this to an art form by spinning bits in Phillips head screws until a > smooth conical crater formed, eliminating all hope of removing the > screws at some later date. Other manufacturers tried, but never quite > reached Kimball's level of expertise at screw head stripping. >> Square-drive fasteners are great for assembly work as long as the drivers >> don't round over. > > Or more likely, break. That was also the idea behind hex drive and the > spline type that (I think) Aeolean used in their vertical backs. > > >> Even though the Phillips configuration took over in the >> U.S. there have always been a few holdouts who continued using >> square-drive >> screws. I guess Grand was one of them. Somebody back then told me >> Grand used >> Robertson's screws from the start. At least that was where I first saw >> them--I had to track down a driver with a square blade to fix one. In the >> 1960s in San Bernardino, CA that wasn't easy. > > That sounds likely. > Ron N
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