| 摘要 |
<p>A spiral member (140) for improving the grip of screws (20) in wooden or other receptive substrates is disclosed. The spiral member (140) has a central axial drive pin by which it can be driven into a thread in the receptive substrate and has an improved cross section providing wings or protuberances (190, 191) extending out past the side surfaces of the cross section. The spiral member (190) has an outwardly facing triangular apex (174) which bites into the old thread whilst the wings (190, 191) bear upon the flanks of the screw thread of the screw inserted (20) into the spiral member (140) improving the grip.</p> |
