Lathe

In woodworking and metalworking, a lathe is a machine tool which spins a block of material so that when abrasive or cutting tools are applied to the block, it can be shaped to produce an object which has rotational symmetry about an axis of rotation. Examples of objects that can be produced on a lathe include candlestick holders, table legs, bowlss, baseball bats, crankshafts or camshafts.

The material is held in place by two centers, at least one of which can be moved horizontally to accommodate varying material lengths. An adjustable horizontal metal rail between the material and the operator accommodates the positioning of shaping tools. With wood, it is common practice to press and slide sandpaper against the still-spinning object after shaping.

In a metalworking lathe, metal is removed from the workpiece using a hardened cutting tool, which is usually fixed to a solid moveable mounting called the "toolpost". This is in contrast to a woodworking lathe where most tools are hand held. The toolpost is manually operated by a leadscrew to position the tool in a variety of planes. The toolpost may also be automatically driven to produce automatic finishing of a piece, or for cutting threads, gears, etc. Cutting fluid may also be pumped to the cutting site to provide cooling, lubrication and clearing of swarf from the workpiece. Some lathes may be operated under control of a computer for mass production of parts (see "Computer Numerically Controlled", or CNC).

The workpiece may be supported between a pair of hardened points called centres, or it may be bolted to a faceplate or held in a chuck. A chuck has movable jaws that can grip the workpiece. For a metal lathe, the tool is situated in the toolpost which sits on the cross slide which is on the saddle. The saddle moves along the axis of the workpiece, and the cross slide moves perpendicular to the axis. The movements are normally calibrated so that precise cuts can be made. An additional slide called a topslide is often present, and this can be angled to permit cutting short tapers. A screwcutting lathe has provision for gearing the feed along the axis to the drive rotating the workpiece. Suitable choice of ratios permits screw threads to be cut and also allows for an automatic fine feed. This allows the operator to stand and watch. With ingenuity, a lathe can perform many diverse machining tasks, although the size of work may be limited compared to special machines.

See also

• metalworking
• woodworking

  External Links

• Medieval and Renaissance Lathes: http://www.his.com/~tom/sca/lathes.html
• The development of the lathe: http://www.stuartking.co.uk/articles/lathe.htm
• Early Wood-Working: http://www.regia.org/woodwork.htm
• Spring pole lathe: http://www.historicgames.com/lathes/springpole.html
• Lathes Cnc and Manual http://www.machinetools.btinternet.co.uk
• Lathes and other small machine tools for the enthusiast and professional: http://www.lathes.co.uk/index.html
• 7x10, 7x12 and 7x14 Asian mini-lathes: http://www.mini-lathe.com/