Stainless Steel Self Tapping Wood Self-drilling Screw

screw,Anchor in machine construction, a usually circular cylindrical member with a continuous helical rib, used either as a fastener or as a force and motion modifier.Hex Bolt

Although the Pythagorean philosopher Archytas of Tarentum (5th century BC) is the alleged inventor of the screw, the exact date of its first appearance as a useful mechanical device is obscure. Though invention of the water screw is usually ascribed to Archimedes (3rd century BC), evidence exists of a similar device used for irrigation in Egypt at an earlier date. The screw press, probably invented in Greece in the 1st or 2nd century BC, has been used since the days of the Roman Empire for pressing clothes. In the 1st century AD, wooden Screws were used in wine and olive-oil presses, and cutters (taps) for cutting internal threads were in use.Hex Nut