Lathe

Parts

1. Headstock

hollow spindle gear box

2. Tailstock

handwheel locks

3. Bed (ways) carriage made up of saddle and apron» cross slide» compound rest (rotates to any angle) &

holds tool post» half nut lever - used only for cutting threads» thread dial

feed rod - general turning lead screw (Acme thread) - for threading

only

4. Base

Lathe spindle - internal Morse taper at nose

end

centers collet assemblies

Outside the spindle nose

threaded nose long taper with drive key camlock

Spring cleaner

Spindle Tooling

1. Independent 4 jaw chuck

most precise most difficult to set up holds work more securely oddly shaped pieces use dial indicator for centering work piece can reverse jaws jaws are removed 3,2,1 and returned in

order of 1,2,3

2. Universal 3 jaw chuck

some 2 or 6 jaws easier to set up less precise jaws will not reverse so a separate set of

jaws must be used chucking» normal» external» internal

3. Drive plate

used with lathe dog to drive work mounted between centers

4. Face plate

can mount work directly to face of plate

has T-slots

5. Collets for small detailed work range only few thousandths of inch work pieces to be gripped must not vary more

than +/- .003” rough or inaccurate work - don’t use with collet never tighten a collet without a workpiece in its

jaws rubber flex collets - have a wider range

(about .125”)

6. Magnetic chuck

Tailstock

jacobs chuck (drills) taper shank drills centers

Operating the machine controls

Hand feeding is not used for long cuts

lack of uniformity poor surface finish

Using power feed and approaching a

shoulder, disengage 1/8” before shoulder

Micrometer collar graduations

single depth - tool moves as much as the collar shows

you are actually removing twice as much from the diameter

turn in .020” , actually moves in .020” removing .040” from dia.

some lathes built to compensate - turn in .020”, actually moves in .010” to remove .020” from dia.

Operations on the lathe

1.) Facing

to obtain flat surface on end of work piece

Why is facing done?

to establish lengths before center drilling on parts clamped on face plate

Tool must be at centerline of work

Lock carriage when facing

Can feed in either direction when facing

1. feed from center to outside» better surface finish» difficult to cut on a solid face in the center

2. feed from outside to center (preferred)» can take heavier cuts» easier to cut to scribed lines on the

circumference of the work

Feed by hand for small diameters

Methods of facing to length

face to layout line » less precise

turn compound slide parallel to the ways and use micrometer dial»most precise

2.) Center Drilling

also called combination drill and countersink

performed because the hole must have 60 deg angle to clear point of center

range from 1/8” to 3/4” body diameter don’t feed drill too fast don’t feed drill too deep

3.) Turning between centers (done after facing and center

drilling)

Adv:

can turn without eccentricity can turn more of a shaft

Disadv:

no parting no boring no drilling

Accessories needed

tailstock center headstock center drive plate lathe dog knockout bar

Adjust tailstock so the bent tail of the dog

moves freely in its slot

Lathe dog tail should not rub on the bottom

of the slot

4.) Turning between chuck and a center

Adv:

quick setup positive drive

Disadvantage:

eccentricities on a shaft can be caused by chuck jaw inaccuracies

work piece slips endwise into the chuck - come off tailstock center

solutions to this» 1. make chalk mark at chuck to monitor

slipping» 2. machine a shoulder on the shaft to contact

face of chuck

Cutting tools and tool holders

General Single Point Turning Tools

HSS Carbide» greater rigidity» greater material removal rates

Tool geometries (shape of tool)

grooving / parting threading knurling boring - boring bar

Tool holders and Tool posts

mounted on compound rest and held in T-slot

1. Standard type (obsolete)

straight shank left hand right hand

2. Quick change

Tools should be set on the centerline of the

work piece for turning (as well as for facing)

can set this by checking with the center in the tailstock

can set this by using a steel rule

Checking alignment of lathe centers (4

methods)

points of centers brought together tailstock witness marks test bar - uses dial indicator mounted

on tool post cutting and measuring (most

accurate)