lucienballard: Robertson’s crew drive patent application. A Robertson’s crew drive, also known as a square,or Scrulox screw drive has a square-shaped socket in the screw head and a square protrusion on the tool. Peter Lymburner Robertson invented
lucienballard: Robertson’s crew drive patent application. A Robertson’s crew drive, also known as a square,or Scrulox screw drive has a square-shaped socket in the screw head and a square protrusion on the tool. Peter Lymburner Robertson invented
