ABSTRACT
Screws have changed considerably with twin thread, deep-cut thread and steeper thread angles extending along the entire shank to provide a better grip and speedier driving performance. They also now have at least seven variations in slotted head-design, ranging from the traditional straight-slotted head to the Torx-or T Star-slotted head. With the revolutionary change from hand screwdrivers to electric and cordless drill/drivers, the development in slotted-head types was necessary to create a more secure, non-slip driving attachment. Improved slotted heads such as Uni-Screw and Torx/T Star promote non-wavering driving alignment, virtually eliminating so-called camout situations. Like nails, screws also come in collated strips for use in mains powered, automatic-feed screwdrivers. The screws for these drivers have
a bugle-shaped head, which is an innovative countersunk shape allowing them to sit at the correct depth in plasterboard without tearing the paper. These auto-feed drivers have been marketed particularly for drywall operations – fi xing plasterboard to lightweight steel or timber stud-partitions – but can be used on other repetitive screwing operations such as fi xing sheet material to wood fl oors prior to tiling, or sheet material to fl at roofs prior to felt or GRP roofi ng. For these operations, collated fl oorboard-screws, with ordinary countersunk heads, are available.
