Transcript Lathe

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

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)
