[pianotech] Un-Grand revisited

[Ron Nossaman]

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