It is a random accessory for milling machines and drilling machines.It is fixed to the machine tool table and used to hold the workpiece for cutting.

1. Use of precision vise
precision vise, also known as machine vise, are a general-purpose fixture commonly used to install small workpieces.It is a random accessory for milling machines and drilling machines.It is fixed to the machine tool table and used to hold the workpiece for cutting.
2. The working principle of precision vise
Turn the screw with a wrench, and drive the movable clamp body to move through the screw nut to form a tightening and loosening of the workpiece.
 The size of the clamped workpiece shall not exceed 70 mm.
3. Structure of precision vise
The assembly structure of precision vise is a detachable threaded connection and pin connection; the linear movement of the movable pliers body is transformed by spiral movement; the working surface is the friction surface of the spiral pair, the guide rail pair, and the shaft and hole with the gap.As can be seen from Figure 2-2, the precision vise are concise in composition and compact in structure.
4. Precautions for clamping workpieces in precision vise： 
(1) The processed surface of the workpiece must be higher than the jaw, otherwise the workpiece must be raised with parallel pad iron.
  
(2) In order to be able to clamp firmly and prevent the workpiece from loosening during planing, the relatively dry plane must be tightly attached to the pad iron and jaws.To make the workpiece tightly attached to the pad iron, it should be clamped on one side and lightly hit the sub-surface of the workpiece with a hand hammer on the other. The smooth plane should be tapped with a copper rod to prevent knocking on the smooth surface. 
(3) In order not to damage the jaws and maintain the machined surface, a copper sheet is padded at the jaws when clamping the workpiece.
 
D. Move the pad iron by hand to check the degree of clamping. If it is loose, it means that the fit between the workpiece and the pad iron is not good. The precision vise should be loosened and re-clamped.
(4) Insufficient rigidity: the workpiece needs to be supported to avoid deformation of the workpiece by clamping force.
Bench vise:
Purpose: The device is installed on the workbench to clamp and stabilize the processed workpiece, which is an essential tool for the fitter workshop.The turntable clamp body can be rotated to rotate the workpiece to a suitable working position.