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E-MAIL Tony@lathes.co.ukHome  Machine Tool Archive  Machine-tools for Sale

Machine Tool Manuals  Machine Tool Catalogues  Belts

Lathe Parts- being a brief description of the names and functions of parts -

We can supply parts & accessories for machine tools of all kinds: cross-feed screws and nuts, T-slotted cross slides, backplates,gears of kinds, parts repaired, etc. one-off items a speciality. email your needs

Screwcutting  Countershafts  Backgear   The Watchmaker's Lathe  Tumble Reverse

Quick-change Toolholders Fitting a Chuck  Spindle Nose Fittings  More Names of Parts

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Having changed over the years, the names given to various parts of the lathe are still not completely standardised. No doubt when the government has finished organising every other aspect of our lives it will appoint a highly- paid commission to look into the matter and make "recommendations".If you would like to buy a book or CD to extend your knowledge of lathes - and how to operate them - look on thehome page and here.Illustrations of the parts discussed can be found by following the various hyperlinks and also at the bottom of this

 page. It may be that an Instruction Manual, an Illustrated Parts Book or informative sales Literature may beavailable for your lathe: you can check by clicking here.It's still sometimes possible to see advertisements that refer to certain capabilities:

"SS" - sliding and surfacing i.e. with a power feed that slides the carriage along the bed and the cross slide acrossit."BG" - back geared for slow speeds (see below)"BGSC" - back geared and screwcutting

BEDThe bed of the lathe provides the foundation for the whole machine and holds the headstock, tailstock and carriagein alignment. The surfaces of the bed that are finely machined - and upon which the carriage and tailstock slide -are known as "ways".Some beds have a gap near the headstock to allow extra-large diameters to be turned. Sometimes the gap isformed by the machined ways stopping short of the headstock, sometimes by a piece of bed that can be unbolted,removed--and lost.Some very large lathes have a "sliding bed" where the upper part, on which the carriage and tailstock sit, can beslid along a separate lower part - and so make the gap correspondingly larger or smaller.

SADDLEThe casting that fits onto the top of the bed and slides along it is known, almost universally, as the "Saddle" - aself-explanatory and very suitable term.

APRONThe vertical, often flat and rectangular "plate" fastened to the front of the "Saddle" is known as the "Apron" andcarries a selection of gears and controls that allow the carriage to be driven (by hand or power) up and down the

 bed. The mechanism inside can also engage the screwcutting feed and various powered tool feeds, should they befitted. The leadscrew, and sometimes a power shaft as well, are often arranged to pass through the apron and

 provide it with a drive for the various functions. The sophistication of the apron-mounted controls, and their easeof use, is a reliable indicator of the quality of a lathe. Virtually all screw-cutting lathes have what is commonly-called a "half-nut" lever that closes down one and sometimes two halves of a split nut to grasp the leadscrew and

 provide a drive for screwcutting.Apron design can be roughly divided into "single-wall" and "double-wall" types. The "single-wall" apron has justone thickness of metal and, protruding from it (and unsupported on their outer ends) are studs that carry gears.The "double-wall" apron is a much more robust structure, rather like a narrow, open-topped box with the gear-carrying studs fitted between the two walls - and hence rigidly supported at both ends. This type of construction

 produces a very stiff structure - and one that is far less likely to deflect under heavy-duty work; another advantageis that the closed base of the "box" can be used to house an oil reservoir the lubricant ion which is either splashedaround or, preferably, pumped to supply the spindles, gears and even, on some lathes, the sliding surfaces of the

 bed and cross slide as well.

COMPOUND SLIDE REST consisting of the CROSS SLIDE and TOP SLIDESitting on top of the "Saddle" is the "Cross Slide" - that, as its name implies, moves across the bed - and on top of that there is often a "Top Slide" or "Tool Slide" that is invariably arranged so that it can be swivelled and locked

into a new position.Very early lathes had a simple T-shaped piece of metal against which the turner "rested" his tool (all turning beingdone by hand) but when it became possible to move this "Rest" across the bed by a screw feed it became known,appropriately enough, as a "Slide-rest". The earliest known example of a "Slide-rest" is illustrated inMittelalterliche Hausbuch, a German publication of about 1480.After the "Top Slide" became a more common fitting the term "Slide-rest" was not so frequently used - and thedifferent functions of the two slides led to their specific names being more widely adopted.When two slides are provided (or sometimes, on watchmaker's lathes, three) the complete assembly is known asthe "Compound" or "Compound Slide" or even "Compound Slide-rest". Some makers have been known to labelthe "Top Slide" as the "Compound Rest" or even the "Compound Slide" - but as "to compound " means the 'joiningof two or more' - not 'one' - this use of the term in incorrect. The top and cross slide together should be referred

to as "the compound".

CARRIAGE

The whole assembly of Saddle, Apron, Top and Cross Slide is known as the "Carriage". Some American publications (even makers' handbooks) have been known to casually refer to this as the "Saddle" - but thisincorrect.

HEADSTOCK .The lathe Headstock used, at one time, to be called the "Fixed Headstock" or "Fixed Head", and the rotating shaft

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LATHE MACHINE

Working Principle: The lathe is a machine tool which holds the workpiece between two rigid and strong supports

called centers or in a chuck or face plate which revolves. The cutting tool is rigidly held and supported in a tool

post which is fed against the revolving work. The normal cutting operations are performed with the cutting tool fed

either parallel or at right angles to the axis of the work.

The cutting tool may also be fed at an angle relative to the axis of work for machining tapers and angles.

Construction: The main parts of the lathe are the bed, headstock, quick changing gear box, carriage and

tailstock.

1. Bed: The bed is a heavy, rugged casting in which are mounted the working parts of the lathe. It carries the

headstock and tail stock for supporting the workpiece and provides a base for the movement of carriage assembly

which carries the tool.

2. Legs: The legs carry the entire load of machine and are firmly secured to floor by foundation bolts.

3. Headstock: The headstock is clamped on the left hand side of the bed and it serves as housing for the driving

pulleys, back gears, headstock spindle, live centre and the feed reverse gear. The headstock spindle is a hollow

cylindrical shaft that provides a drive from the motor to work holding devices.

4. Gear Box: The quick-change gear-box is placed below the headstock and contains a number of different sized

gears.

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5. Carriage: The carriage is located between the headstock and tailstock and serves the purpose of supporting,

guiding and feeding the tool against the job during operation. The main parts of carriage are:

a). The saddle is an H-shaped casting mounted on the top of lathe ways. It provides support to cross-slide,

compound rest and tool post.

b). The cross slide is mounted on the top of saddle, and it provides a mounted or automatic cross movement for

the cutting tool.

c). The compound rest is fitted on the top of cross slide and is used to support the tool post and the cutting tool.

d). The tool post is mounted on the compound rest, and it rigidly clamps the cutting tool or tool holder at the

proper height relative to the work centre line.

e). The apron is fastened to the saddle and it houses the gears, clutches and levers required to move the carriage

or cross slide. The engagement of split nut lever and the automatic feed lever at the same time is prevented she

carriage along the lathe bed.

6. Tailstock: The tailstock is a movable casting located opposite the headstock on the ways of the bed. The

tailstock can slide along the bed to accommodate different lengths of workpiece between the centers. A tailstockclamp is provided to lock the tailstock at any desired position. The tailstock spindle has an internal taper to hold

the dead centre and the tapered shank tools such as reamers and drills.

LATHE OPERATIONS

The engine lathe is an accurate and versatile machine on which many operations can be performed. These

operations are:

1. Plain Turning and Step Turning

2. Facing

3. Parting

4. Drilling

5. Reaming

6. Boring

7. Knurling

8. Grooving

9. Threading

10. Forming