A Canadian named P. L. Robertson invented the Robertson screw and screwdriver in 1908, which uses a square-shaped tip with a slight taper. The Robertson screw-driver uses color-coded handles because different size screws required different tip sizes. The color and sizes include:
Orange (#00) — Number 1 and 2 screws
Yellow (#0) — Number 3 and 4 screws
Green (#1) — Number 5, 6, and 7 screws
Red (#2) — Number 8, 9, and 10 screws
Black (#3) — Number 12 and larger screws
The Robertson screws are rarely found in the United States but are common in Canada.
Safe Use of Screwdrivers Always use the proper type and size screwdriver that matches the fastener.
Try to avoid pressing down on a screwdriver because if it slips, the screwdriver tip could go into your hand, causing serious personal injury.
All screwdrivers should be cleaned after use.
Do not use a screwdriver as a pry bar; always use the correct tool for the job.
No comments:
Post a Comment