What is Screw thread?
[[File:Acme_thread.jpg|thumb|A piece of threaded rod]] A '''screw thread''', often shortened to '''thread''', is a [[helix|helical]] structure. It is a ridge wrapped around a [[cylinder (geometry)|cylinder]] or [[cone]] in the form of a helix, with the former being called a ''straight'' thread and the latter called a ''tapered'' thread. [[File:BOLT_SCREW_UBT_199.JPG|thumb|Nuts, bolts, and screws all have screw threads]] The tightening of a [[nut (hardware)|nut]] to a [[bolt (fastener)|bolt]] is like driving a [[wedge (mechanics)|wedge]] into a gap until it sticks through [[friction]] and plastic deformation (how the surfaces of the two objects slightly squash together). A screw thread is one of the six [[simple machine]]s which give [[mechanical advantage]]. The [[mechanical advantage]] of a screw thread depends on its ''lead'', which is the linear distance the screw travels in one turn or revolution.<ref>{{cite book| last = Burnham| first = Reuben Wesley| title = Mathematics for Machinists| url = https://books.google.com/books?id=IRdIAAAAIAAJ&pg=PA137| year = 1915| publisher = John Wiley & sons, Incorporated| isbn = | page = 137 }}</ref> [[File:Lead_and_pitch.png|thumb|Two screw threads with the same pitch and diameter, but a different lead]] == References == {{reflist}} [[Category:Machines]]