A machine vise is a clamping device that is used on a drill press or milling machine. Manufactured with a flat bottom designed to fit firmly against the machine's bed, the machine vise has provisions to be bolted securely in place on the bed of either machine. Offered in variations from a simple, single jaw flat vice used to hold one piece of material to be drilled or machined, to multi-jawed, multi-adjustable machine vise designs, the vices are likened to an additional pair of hands by many machinists. Vices that are capable of holding the work at various angles allow the machinist to make machining corrections as the machine is operated. This allows the machinist to perform a wide array of drilling and machining tasks.
Unlike a traditional bench vise, the machine vise is used on the drill press or milling machine to hold a part that is being machined. The typical machine work bed contains various holes and slots that the machine vise can be bolted to, allowing the vice to be mounted in a wide array of positions. Instead of a large handle to tighten the vice jaws, as used on a bench vice, the machine vise uses small cranks that are geared to apply maximum clamping force without turning the handle excessively. This is due primarily to the close proximity of the vice to the work bed of the machine.
Due in part to the many different metals that are machined for any given purpose, the machine vise is commonly equipped with interchangeable jaws to allow most metals to be clamped into the vice without leaving damaging marks on the finish of the parts. Brass, aluminum and copper jaw inserts are available for most models of machine vise. These typically will not scratch or mar the finish of delicate metals or finished surfaces of steel components.
Many machinists will have a variety of vices at their disposal to allow for a wide array of clamping positions and arrangements. Often, a large part will require the use of two or more vices set up in a series to hold the part and prevent unnecessary movement while it is being drilled or machined. Some versions of the machine vise are magnetized to aid in holding the workpiece while the vice is being adjusted. Some also have magnetized bases to hold the vice to the work bed without the aid of bolts.