Differentiation Between Bolt and Screw
There is no universally accepted distinction between a screw and a bolt. Machinery's Handbook describes the distinction as follows:
A bolt is an externally threaded fastener designed for insertion through holes in assembled parts, and is normally intended to be tightened or released by torquing a nut. A screw is an externally threaded fastener capable of being inserted into holes in assembled parts, of mating with a preformed internal thread or forming its own thread, and of being tightened or released by torquing the head. An externally threaded fastener which is prevented from being turned during assembly and which can be tightened or released only by torquing a nut is a bolt. (Example: round head bolts, track bolts, plow bolts.) An externally threaded fastener that has thread form which prohibits assembly with a nut having a straight thread of multiple pitch length is a screw. (Example: wood screws, tapping screws.)This distinction is consistent with ASME B18.2.1 and some dictionary definitions for screw and bolt.
The issue of what is a screw and what is a bolt is not completely resolved with Machinery's Handbook distinction, however, because of confounding terms, the ambiguous nature of some parts of the distinction, and usage variations. Some of these issues are discussed below:
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Famous quotes containing the words bolt and/or screw:
“He said there was gold here. He lied. He is not perfect.”
—Robert Bolt (1924–1995)
“Let us have a good many maples and hickories and scarlet oaks, then, I say. Blaze away! Shall that dirty roll of bunting in the gun-house be all the colors a village can display? A village is not complete, unless it have these trees to mark the season in it. They are important, like the town clock. A village that has them not will not be found to work well. It has a screw loose, an essential part is wanting.”
—Henry David Thoreau (1817–1862)