A tail vise is one of the many specialized components of a woodworker’s workbench designed to secure workpieces for planing, cutting, sanding, or other operations. Traditionally, it consists of a solidly built wooden frame of up to 6 inches (15.24 cm) wide and deep by 24 inches (60.96 cm) long, the exact dimensions being a matter of preference for the woodworker. This frame is secured within a notch of equal or similar dimensions cut out of the right-hand portion of the workbench’s front to accommodate it. The frame contains a long, sturdy screw of up to an inch (2.54 cm) in diameter, which threads through a nut that's part of a frame attached to the bench.
There are a few different tasks that a tail vise can perform. When the wooden handle controlling the screw is turned clockwise, the frame will move to the left until its face, usually specially constructed of a hardwood block, meets a corresponding wooden block built into the bench. This exerts a strong clamping action on any workpiece fixed between these wooden blocks, called jaws, securing it for work. Turning the handle counterclockwise will move the frame to the right. The force of this movement can be used to pull apart glued-up joints for re-work or repair.
The primary vise on a workbench, called the front vise or the face vise, is located at the front left-hand corner of the bench for a right-handed woodworker. A workpiece clamped by the face vise has its top surface running parallel to the bench’s front. A tail vise often supplements or supports the action of the front vise. For example, the front vise might be used to clamp a long board for work on its edge, and another piece of stock would be clamped in the tail vise to support the board’s length.
One of the benefits of a tail vise is that it offers an alternative to the front vise, which can only clamp workpieces parallel to the workbench’s front. Tail vises clamp workpieces perpendicular to the front of the bench, but generally cannot be used with long workpieces. Nevertheless, there are many situations where this capability is extremely useful for the woodworker.
Most workbenches are fitted with special holes called dogholes. Different types of tools are placed into them and workpieces are butted up against them or clamped against them. These tools, called planing stops, dogs and hold fasts, can be used to secure one end of a workpiece. Dogs can then be placed in dogholes in the tail vise, which can be tightened to clamp the workpiece lengthwise and secure it for a wide range of different work.
Tail vises were once an integral element of every woodworker’s workbench, but contemporary woodworkers sometimes find that they can be as efficient or even more so without them. The use of dogs, wedges and hold fasts, among others, usually gives the woodworkers the clamping power of a tail vise. In addition, it's often easier to work with the doghole tools, rather than having to tighten and loosen a tail vise whenever the workpiece needs re-aligning.