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)