An Introduction to the Engine Lathe By Trevor Rutz

The Lathe The Lathe is one of the most important machine tools used in the metalworking industry. Before you are able to operate this machine, you must learn the names and function of the various parts of the lathe.

Headstock The Headstock is fastened on the upper left side of the lathe. It contains the spindle that drives the various work holding devices.

Spindle Speed Levers Spindle speed changes are made by shifting the levers on the headstock. Make sure the spindle has stopped rotating before you switch the RPM. If you have trouble getting a lever to go into gear try turning the chuck by hand until the lever falls into gear.

Quick Change Gearbox Used to select the rate of travel for turning, facing, and threading. The Quick Change Gearbox is located below the headstock. It is used to select the rate of travel of the carriage and cross slide. The Quick Change Gearbox is also used to create the desired speed of rotation of the lead screw when threading.

Lead Screw and Feed Rod < Lead Screw < Feed Rod In this illustration, the lead screw is the top threaded shaft. Its purpose is to provide transfer of mechanical movement from the Quick Change Gearbox to the carriage when threading. Directly below the lead screw is the feed rod. The feed rod transfers mechanical movement to the carriage and cross slide when turning or facing.

Thread Chasing Dial References the rotation of the lead screw. The thread chasing dial is used to reference the rotation of the lead screw so that cuts will always be made in same groove when threading.

Carriage < Saddle < Apron The Carriage is made up of the Saddle and Apron. The Apron is the part of the carriage facing the operator. The Saddle slides longitudinally on the ways and supports the cross slide and compound rest.

Ways Hardened sliding surfaces. Do not damage the ways! The ways are very accurately machined sliding surfaces on which the carriage saddle moves. Wear or damage to the ways will affect the accuracy of workpieces machined by the lathe.

Bed Made of Cast Iron Backbone of Lathe The ways are supported by the lathe bed. The bed is usually made of heavy cast iron and can be thought of as the backbone of the lathe.

Tailstock Supports long workpieces when machining. The tailstock also slides on the ways. It is used to support the end of long workpieces when machining.

Rotating Center 60 degree rotating center point. A rotating center is fitted into the Morse taper of the tailstock ram. The 60 degree taper of the revolving center point fits the 60 degree center drilled hole in the end of a workpiece shaft.

Drill Chuck The tailstock can also accept a drill chuck to drill holes in the center of a rotating workpiece.

Tailstock Handwheel Turn the tailstock handwheel to advance the ram. The ram of the tailstock is advanced by turning the tailstock handwheel.

Cross Slide < Used for facing. The cross slide sits on top of the carriage saddle. It produces a cross feed travel used for facing the end of a workpeice.

Compound Rest Used for: Short steep tapers Accurate shoulder lengths The Compound Rest sits on top of the cross slide. It can be used to machine shoulders on a workpiece to an accurate length. The Compound Rest can also be rotated a number of degrees to machine short steep tapers.

Tool Post The Tool Post sits on top of the Compound Rest. It is used to hold the various cutting tools used in lathe work.

3 Jaw Chuck All 3 jaws move together. The 3 Jaw Chuck is one of the most common work holding devices. All 3 jaws move at the same time so they accurately center the workpiece.

4 Jaw Chuck All 4 Jaws move independently Very accurate The 4 Jaw Chuck is another work holding device. All 4 jaws move independent of each other. It can be used to hold irregular shaped workpieces and can be very accurate when used with a dial indicator.

Chuck Wrench Never let me catch you doing this! Never leave the chuck wrench in the chuck. It could fly out and hurt you or someone else if you accidentally turn the lathe on.

Operator Lets Keep it Safe The most important part of the lathe is you the operator. Make sure you are familiar with all parts of the lathe and observe all safety procedures. Watch a demonstration and participate in guided practice from your teacher before you operate the lathe on your own. Lets Keep it Safe