A vise (American) or vice (British) is a mechanical apparatus used to secure an object to allow work to be performed on it. Vises have two parallel jaws, one fixed and the other movable, threaded in and out by a screw and lever.
Woodworking vises are attached to a workbench, typically flush with its work surface. Their jaws are made of wood or metal, the latter usually faced with wood to avoid marring the work. The movable jaw may include a retractable dog to hold work against a bench dog.
"Quick-release" vises employ a split nut that allows the screw to engage or disengage with a half-turn of the handle. When disengaged the movable jaw may be moved in or out throughout its entire range of motion, vastly speeding up the process of adjustment. Common thread types are Acme and buttress.
Engineer's bench vise made of cast iron - image inset shows soft jaws
A small machine vise used in a drill press
A machine vise that can be rotated
An engineer's vise, also known as a metalworking vise or fitter's vise, is used to clamp metal instead of wood. It is typically made of cast steel or malleable cast iron. Cheaper vises may be made of brittle cast iron. The jaws are often separate and replaceable, usually engraved with serrated or diamond teeth. Soft jaw covers made of aluminum, lead, or plastic may be used to protect delicate work.
An engineer's vise is bolted onto the top surface of a workbench, with the face of the fixed jaws just forward of its front edge. The vise may include other features such as a small anvil on the back of its body.
Aluminum soft jaw shown holding five parts at a time in a CNC milling machine.
Other kinds of vise include:
Machine vises - drill vises (lie flat on a drill press bed). Vises of the same general form are used also on milling machines and grinding machines.
compound slide vises are more complex machine vises. They allow speed and precision in the placement of the work.
Cross vises, which can be adjusted using leadscrews in the X and Y axes; these are useful if many holes need to be drilled in the same workpiece using a drill press. Compare router table.
Sine vises, which use gauge blocks to set up a highly accurate angle
Pin vises (for holding thin, long cylindrical objects by one end)
Jewellers' vises and by contrast
Leg vises, which are attached to a bench but also supported from the ground so as to be stable under the very heavy use imposed by a blacksmith's work.