A face driver has two main components, the drive head and the mounting. The mounting locates the driver in the machine with either a morse taper shank mount directly into the machine taper; or a chuck mount chucked between special chuck jaws; or a flange mount bolted to a spindle adapter on the machine spindle. The illustration shows a morse taper shank. The drive head (also known as a carrier body) contains the compensating medium (hydraulic or mechanical); which allows the pins to adjust to variations in the locating face and the spring-loaded center point. Face driving is a simple two step clamping operation, centering followed by clamping. Under tailstock pressure, the workpiece engages the center point which locates the part and provides a consistent axis of rotation. As the tailstock continues to drive the workpiece against the center point, the axial pressure forces the spring-loaded center point back into the carrier body until the drive pins engage the face of the workpiece. Each pin individually compensates for any irregularities in the face until all of the pins are fully engaged. Under the increasing axial load, the drive pins penetrate the workpiece completing the clamping operation, while the center point maintains the axis of rotation.
The compensating medium (either hydraulic or mechanical) in the face driver assures equal penetration of the drive pins despite variations in the surface or in the squareness of the face. Therefore, surface imperfections or out of square saw cuts do not present a problem when face driving.
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A center is a tool that has been ground to an included angle of 60 ° (sometimes other angles are used depending on the center hole machined in to the workpiece) and is used to accurately position a workpiece about its axis.

Centers are normally used on longer workpieces when accurate support is required to insure the finished product is within the tolerance specified on the design. Most of the parts are machined from a raw piece of steel in the form of bar stock, castings or forgings while located between two centers. This establishes the axis of rotation within a very tight tolerance typically within .0001" T.I.R. This initial process is usually done on a lathe. Subsequent operations can also use centers to locate the workpiece. These may include gear shaping, gear hobbing, or spline rolling, induction heat treating and final grinding among others. Utilizing the same location points allows the workpiece to be transferred between operations without any loss of accuracy.

The centers locate the workpiece into a matching hole machined in to the part by a center drill typically in the first machining operation performed.

A dead center (one that does not turn freely, ie:- dead) may be used to support the workpiece at either the fixed or rotating end of the machine. When used in the fixed position, a dead center produces friction between the workpiece and center, due to the rotation of the workpiece. Lubrication is therefore required between the center and workpiece to prevent friction welding from occurring. Additionally the tip of the center may have an insert of carbide which will reduce the friction slightly and allow for faster speeds. Dead centers may also be fully hardened to prevent damage to the important mating surfaces taper of the taper and to preserve the 60 ° nose tap

A half dead center refers to a dead center that has material removed from its major diameter. This "flat" allows clearance for the tool used in machining the part, typically a grinding wheel on a cylindrical grinder.

A live center or revolving center is constructed so that the 60 ° center runs in its own bearings and is used at the non driven or tailstock end of a machine. It allows higher turning speeds without the need for separate lubrication, and also greater clamping pressures. They are used almost exclusively in CNC lathes as well as for general machining operations.

A vise is a mechanical screw apparatus used for holding or clamping a work piece to allow work to be performed on it with tools such as saws, planes, drills, mills, screwdrivers, sandpaper, etc. Vises usually have one fixed jaw and another, parallel, jaw which is moved towards or away from the fixed jaw by the screw.

Without qualification, "vise" usually refers to a bench vise with flat, parallel jaws, attached to a workbench.

A woodworker's bench vice is a more or less integral part of the bench.
An engineer's bench vise is bolted onto the top of the bench.
Other kinds of vise include:
hand vises (hand-held),
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.
Mtalworkers' vises
For metalworking, the jaws are made of metal which may be hardened steel with a coarse gripping finish. Removable soft jaws are usually kept for use where appropriate, to protect the work from damage.

Metalworking bench vises, known as engineers' or fitters' vises, are bolted onto the top surface of the bench with the face of the fixed jaws just forward of the front edge of the bench. The bench height should be such that the top of the vise jaws is at or just below the elbow height of the user when standing upright. Were several people use the one vise, this is a counsel of perfection but is still a good guide.

The nut in which the screw turns may be split so that, by means of a lever, it can be removed from the screw and the screw and moveable jaw quickly slid into a suitable position at which point the nut is again closed onto the screw. Many fitters prefer to use the greater precision available from a plain screw vise. The vise may include other features such as a small anvil on the back of its body but it is in general, better to separate the functions of the various tools.

Vise screws are usually either of an Acme thread form or a buttress thread. Those with a quick-release nut use a buttress thread.

The word 'vise' comes ultimately, from the Latin word vitis (vine), referring to the helical tendrils of the vine. The more direct source is the French vis, screw.

Metalworking vises in Machine Shops
In high production machine work, work must be held in the same location with great accuracy so CNC machines may perform operations on an array of vises. To assist this, there are several machine-shop specific vises and vise accessories.

Hard and soft machine jaws have a very important difference between other metalworking vise jaws. The jaws are precision ground to a very flat and smooth surface for accuracy. These rely on mechanical pressure for gripping, instead of a rough surface. An unskilled operator has the tendency to over-tighten jaws, leading to part deformation and error in the finished workpiece. The jaws themselves come in a variety of hard and soft jaw profiles, for various work needs. One can purchase machinable soft jaws, and mill the profile of the part into them to speed part set-up and eliminate measurement. This is most commonly done in gang operations, discussed below. For rectangular parts being worked at 45 degree angles, prismatic hard jaws exist with V grooves cut into them to hold the part. Some vises have a hydraulic or pneumatic screw, making setup not only faster, but more accurate as human error is removed.

For large parts, an array of regular machine vises may be set up to hold a part that is too long for one vise to hold. The vises' fixed jaws are aligned by means of a dial indicator so that there is a common reference plane for the CNC machine.

For multiple parts, several options exist, and all machine vise manufacturers have lines of vises available for high production work.

The first step is a two clamp vise, where the fixed jaw is in the center of the vise and movable jaws ride on the same screw to the outside.
The next step up is the modular vise. Modular vises can be arranged and bolted together in a grid, with no space between them. This allows the greatest density of vises on a given work surface. This style vise also comes in a two clamp variety.
Tower vises are vertical vises used in horizontal machining centers. They have one vise per side, and come in single or dual clamping station varieties. A dual clamping tower vise, for example, will hold eight relatively large parts without the need for a tool change.
Tombstone fixtures follow the same theory as a tower vise. Tombstones allow four surfaces of vises to be worked on one rotary table pallet. A tombstone is a large, accurate, hardened block of metal that is bolted to the CNC pallet. The surface of the tombstone has holes to accommodate modular vises across all four faces on a pallet that can rotate to expose those faces to the machine spindle.
New workholding fixtures are becoming available for five-axis machining centers. These specialty vises allow the machine to work on surfaces that would normally be obscured when mounted in a traditional or tombstone vise setup.
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