screw

—screwable, adj. —screwer, n. —screwless, adj. —screwlike, adj.

/skrooh/, n.

1. a metal fastener having a tapered shank with a helical thread, and topped with a slotted head, driven into wood or the like by rotating, esp. by means of a screwdriver.

2. a threaded cylindrical pin or rod with a head at one end, engaging a threaded hole and used either as a fastener or as a simple machine for applying power, as in a clamp, jack, etc. Cf. bolt¹ (def. 3).

3. Brit. a tapped or threaded hole.

4. something having a spiral form.

5. See screw propeller.

6. Usually, screws. physical or mental coercion: The terrified debtor soon felt the gangster's screws.

7. a single turn of a screw.

8. a twist, turn, or twisting movement.

9. Chiefly Brit.

a. a little salt, sugar, tobacco, etc., carried in a twist of paper.

b. Slang. a mean, old, or worn-out horse; a horse from which one can obtain no further service.

c. Slang. a friend or employer from whom one can obtain no more money.

d. Slang. a miser.

10. Brit. Informal. salary; wages.

11. Slang. a prison guard.

12. Slang (vulgar).

a. an act of coitus.

b. a person viewed as a sexual partner.

13. have a screw loose, Slang. to be eccentric or neurotic; have crazy ideas: You must have a screw loose to keep so many cats.

14. put the screws on, to compel by exerting pressure on; use coercion on; force: They kept putting the screws on him for more money.

v.t.

15. to fasten, tighten, force, press, stretch tight, etc., by or as if by means of a screw or device operated by a screw or helical threads.

16. to operate or adjust by a screw, as a press.

17. to attach with a screw or screws: to screw a bracket to a wall.

18. to insert, fasten, undo, or work (a screw, bolt, nut, bottle top with a helical thread, etc.) by turning.

19. to contort as by twisting; distort: Father screwed his face into a grimace of disgust.

20. to cause to become sufficiently strong or intense (usually fol. by up): I screwed up my courage to ask for a raise.

21. to coerce or threaten.

22. to extract or extort.

23. to force (a seller) to lower a price (often fol. by down).

24. Slang. to cheat or take advantage of (someone).

25. Slang (vulgar). to have coitus with.

v.i.

26. to turn as or like a screw.

27. to be adapted for being connected, taken apart, opened, or closed by means of a screw or screws or parts with helical threads (usually fol. by on, together, or off): This top screws on easily.

28. to turn or move with a twisting or rotating motion.

29. to practice extortion.

30. Slang (vulgar). to have coitus.

31. screw around, Slang.

a. to waste time in foolish or frivolous activity: If you'd stop screwing around we could get this job done.

b. Vulgar. to engage in promiscuous sex.

32. screw off, Slang.

a. to do nothing; loaf.

b. to leave; go away.

33. screw up, Slang.

a. to ruin through bungling or stupidity: Somehow the engineers screwed up the entire construction project.

b. to make a botch of something; blunder.

c. to make confused, anxious, or neurotic.

[1375-1425; late ME scrwe, screw(e) (n.); cf. MF escro(ue) nut, MD schrûve, MHG schrûbe screw]

Syn. 22. wring, wrest, force, exact, squeeze.

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In machine construction, a usually circular cylindrical member with a continuous spiral rib or thread, used either as a fastener or as a force and motion modifier.

Various types of screws are used to clamp machine parts together. Wood screws are made in a wide variety of diameters and lengths; when using wood screws, small starting holes called pilot holes are often drilled first to avoid splitting the wood. Screws that modify force and motion are known as power screws. The screw is considered one of the five simple machines. See also wedge.

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▪ machine component

      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.

      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.

 In the Figure—>, which shows the main types of screws and screwheads in modern use, the cap and machine screws are used to clamp machine parts together, either when one of the parts has a threaded hole or in conjunction with a nut. These screws stretch when tightened, and the tensile load created clamps the parts together. Machine screws have various types of heads, most with screwdriver slots. They are made in smaller sizes than cap screws and bolts.

 The setscrew in the Figure—> fits into a threaded hole in one member; when tightened, the cup-shaped point is pressed into a mating member (usually a shaft) and prevents relative motion. Setscrews are also made with conical and cylindrical points that fit in matching holes and with slotted and square heads.

      A stud is a rod threaded on both ends. It is permanently screwed into one member and clamped by means of a nut on the other end.

 Self-tapping screws form or cut mating threads in such materials as metals, plastics, glass fibre, asbestos, and resin-impregnated plywood when driven or screwed into drilled or cored (cast) holes. The self-tapping screw in the Figure—> forms threads by displacing material adjacent to a pilot hole so that it flows around the screw. Thread-cutting tapping screws have cutting edges and chip cavities that produce a mating thread by removing material.

      Wood screws are made in a wide variety of diameters and lengths; when using the larger sizes, pilot holes are drilled to avoid splitting the wood. Lag screws are large wood screws used to fasten heavy objects to wood. Heads are either square or hexagonal.

      Screws that modify force and motion are known as power screws. A screwjack converts torque (turning moment) to thrust. The thrust (usually to lift a heavy object) is created by turning the screw in a stationary nut. By using a long bar to turn the screw, a small force at the end of the bar can create a large thrust force. Workpiece tables on machine tools are moved linearly on guiding ways by screws that rotate in bearings at the ends of the tables and mate with nuts fixed to the machine frame. A similar torque-to-thrust conversion can be obtained by either rotating an axially fixed screw to drive a rotationally fixed nut along the screw or by rotating an axially fixed nut to drive a rotationally fixed screw through the nut.

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