1. Lecture 8 Lathe Machine fundamentals
Lathe Fundamentals
Monday, April 24, 2017
Work shop technology
Lecture 8
Lathe Machine
fundamentals

2. Safety Respect the machines Common Sense Wear safety glasses
Lathe Fundamentals
Monday, April 24, 2017
Safety
Respect the machines
Common Sense
Wear safety glasses
Avoid loose clothing
Restrain long hair
Never wear gloves
Never wear shorts or sandals
Remove Necktie
Stay alert

3. Lathe - Introduction The Basics
Lathe Fundamentals
Monday, April 24, 2017
Lathe - Introduction
The Basics
The lathe is one of the most common machines found in today’s modern machine shop. Used primarily to produce cylindrical workpieces.
Different from a mill in that it produces a round diameter on a part by rotating a workpiece against a non-rotating single-point tool, as Figure 1. shows.
The lathe, operated manually, changes the size, shape, and finish of a workpiece with a variety of cutting tools.
Fig. 1

4. Lathe - Introduction Types Of Lathes
Lathe Fundamentals
Monday, April 24, 2017
Lathe - Introduction
Types Of Lathes
The three types of lathes you may find in a machine shop today are:
Engine Lathe
The original lathe is the engine lathe, shown in Fig. 1.
This type of lathe positions and holds a workpiece on a desired centerline, while the spindle rotates the workpiece.
As the workpiece spins, the cutting tool gradually passes along the surface of the workpiece, and a layer of material is removed.
Engine lathes are the most frequently used manual lathes.
Fig. 1

5. Lathe - Introduction Types Of Lathes
Lathe Fundamentals
Monday, April 24, 2017
Lathe - Introduction
Types Of Lathes
Turret Lathe & CNC Machining Centers
The turret holds multiple cutting tools that rotate into position when needed. Each time the turret lever is activated, the turret spins and positions the next tool in the sequence. It is then ready to carry out different machining operations.
Because the turret holds multiple tools, the machinist does not have to change tools each and every time a different tool is needed. There are automated versions of these lathes that are computer controlled and are called CNC Machining Centers.
CNC Machining Center
Turret

6. Lathe - Introduction Types Of Lathes CNC – Lathes
Lathe Fundamentals
Monday, April 24, 2017
Lathe - Introduction
Types Of Lathes
CNC – Lathes
Today, many shops use CNC lathes, like the one in Fig. 1.
A CNC lathe is a type of lathe that uses computer numerical controls (CNC) to operate the lathe. These machines use single bit tooling.
Fig. 1

7. Basic Lathe Terminology
Lathe Fundamentals
Monday, April 24, 2017
Basic Lathe Terminology
Headstock
Chuck
Ways
Tailstock
Feed Gear Box
Cross Slide
Tool Post
Carriage
Brake – Emergency
(E) Stop
Compound Rest
Lead screw
Bed

8. Basic Lathe Terminology
Lathe Fundamentals
Monday, April 24, 2017
Basic Lathe Terminology
Parts Of A Lathe
The bed is the base and backbone of the lathe. The bed is a heavy, rigid frame made of cast iron on which all other components of the lathe are mounted and/or move.
The ways are parallel, longitudinal rails located on the bed. There are two sets of inner and outer ways. The ways guide other components on the lathe, such as the tailstock.
The headstock is mounted on the inner ways and provides the power to rotate the workpiece. It consists of a hollow spindle and a set of gears that rotate the spindle at a range of speeds that are operator adjustable

9. Basic Lathe Terminology
Lathe Fundamentals
Monday, April 24, 2017
Basic Lathe Terminology
Parts Of A Lathe
The spindle is mounted in the headstock and carries the work holding devices, i.e. – chuck. The spindle has a hole extending through its length, through which a long bar stock can be fed. The size of this hole determines the maximum diameter of bar stock that can be machined when the materials must be fed through the spindle.
The tailstock is located opposite of the headstock and supports the end of longer workpieces. The tailstock typically contains a center that holds the other end of the workpiece in place, but it can also hold a cutting tool, by way of a drill chuck.

10. Basic Lathe Terminology
Lathe Fundamentals
Monday, April 24, 2017
Basic Lathe Terminology
Parts Of A Lathe
The carriage is the section of the lathe that slides along the ways and supports the cross-slide and cutting tool. The carriage contains the compound rest, which permits angular adjustment of the cutting tool. The compound rest can rotate with respect to the cross-slide, which permits further positioning of the tool being used.
The leadscrew powers the carriage assembly. The leadscrew is a large, threaded rod that is located below and parallel to the ways.

11. Basic Lathe Terminology
Lathe Fundamentals
Monday, April 24, 2017
Basic Lathe Terminology
Indicating
Dial indicator
Can be attached to bed when digital readout is not present
(Z axis travel indicator)
Used to indicate in a work piece
when using a 4 jaw chuck – a magnetic indicator stand can be used to hold the indicator.

12. Basic Lathe Terminology
Lathe Fundamentals
Monday, April 24, 2017
Basic Lathe Terminology
Tooling
Collets – Work Holding
Collets run more true than a chuck
Drill Chuck – Tool Holding
Mainly for drill bits
Mounts on a Morse Taper
arbor (1 thru 4 most common)
Slides into tailstock
Drill Chuck – Tool Holding
Collets – Work Holding
Morse Taper

13. Basic Lathe Terminology
Lathe Fundamentals
Monday, April 24, 2017
Basic Lathe Terminology
Tooling
Center Drill – used first
Keeps holes accurately positioned
Twist Drill
Reamer
A tool for widening or shaping holes
Precise hole size
Boring Bar – Boring Holes
Lathe Tool Bits – Facing – Turning – Threading - Grooving

14. Basic Lathe Terminology
Lathe Fundamentals
Monday, April 24, 2017
Basic Lathe Terminology
Tool Post & Holder
Tool holders slide down onto tool post
Twist handle to lock and release tool holders

15. Basic Lathe Terminology
Lathe Fundamentals
Monday, April 24, 2017
Basic Lathe Terminology
Work Holding Devices
Chucks – 3 And 4 Jaw Chuck
The most common device used to hold and position parts on the lathe is the chuck. A chuck consists of three or four jaws that clamp down on the end of the workpiece.
The most commonly used chuck has jaws that open and close together automatically centering the workpiece. Chucks are mounted to the lathe spindle using the two most common methods – Spindle Nose with Long-Taper Key Drive (L-Series) & the Cam-Lock Spindle (D-Series)
Threaded Collar
Long-Taper Key Drive - LeBlond
Cam-Lock Spindle - Victor
Cam-Lock Wrench
Long-Taper Wrench

16. Basic Lathe Terminology
Lathe Fundamentals
Monday, April 24, 2017
Basic Lathe Terminology
Work Holding Devices
3 Jaw Chuck
The jaws open and close together automatically centering the workpiece.
This kind of chuck usually has a 2 piece reversible set of jaws, or a complete other set, one set holds the larger work while the other set holds rings and small work.
These 3 jaw universal chucks when in good shape center work accurately to within .002 to .003.
Chuck (key) Wrench
3 Jaw – 2 Piece Reversible
3 Jaw – Solid Jaw (2 Sets)

17. Basic Lathe Terminology
Lathe Fundamentals
Monday, April 24, 2017
Basic Lathe Terminology
Work Holding Devices
4 Jaw Chuck
The 4 jaw independent chuck has four jaws and each must be moved separately with a chuck wrench; it is used mainly to hold work that is not perfectly round.
It may be used to hold work that is round, square, rectangular, or irregular in shape. This chuck is more accurate since the work can be centered with the use of a dial indicator.
The jaws on this kind of chuck are solid reversible; that is, they can be taken out and put on again in the opposite direction or a 2 piece reversible jaw. They have steps so that different sizes of work can be held. There are also 4 jaw self centering chucks available.
4 Jaw – Solid Reversible Jaws
4 Jaw – 2 Piece Reversible Jaws

18. Basic Lathe Terminology
Lathe Fundamentals
Monday, April 24, 2017
Basic Lathe Terminology
Cutting
Facing
Turning
Boring
Taper Turning
Center Drilling
Parting – Grooving
Hole Tapping
Knurling (a small projecting knob or ridge)
Threading
Tapered
Faced
Turned
Parted
Necked

19. Basic Lathe Terminology
Lathe Fundamentals
Monday, April 24, 2017
Basic Lathe Terminology
Feeds and Speeds (F/S)
Spindle Speed:
Speed (rpm) that the spindle and/or chuck rotates
Tool Speed:
[in/min] or [mm/min]: How fast the carriage is moving (Z axis)
Feed Rate:
[mm/rev] relative speed of tool and spindle

20. Cutting Tools Fig. 1 Hand Ground HSS Tool Bits
Lathe Fundamentals
Monday, April 24, 2017
Cutting Tools
Fig. 1
The most common cutting tools used are made from materials such as high-speed tool steels (HSS) and carbide. (a compound of carbon with metal or other element)
Most tools made from these steels are single-point tools, which means they contain a single cutting edge. Single-point tools, shown in Fig. 1 and in the next slide, are the most popular cutting tools used on the lathe – hand ground HSS or the tools shown in Fig. 2 which are Brazed-tipped cutting tools.
These tools are made from inexpensive material with a tip of more expensive cutting material brazed onto the cutting end. These materials include most commonly a C2 or C6 carbide. Carbide tooling can cut many materials at speeds up to four times faster than HSS. C2 – used for non-ferrous metals and C6 used for tougher to machine ferrous metals.
Hand Ground HSS Tool Bits
Brazed Tip Carbide Tool Bits
Fig. 2

21. Cutting Tools – Single Point
Lathe Fundamentals
Monday, April 24, 2017
Cutting Tools – Single Point
Left-Hand Thread Cutting 60deg Right Hand
Cuts Left To Right
Cuts Right To Left
A cutting tools tip should be set to the centerline of the workpiece
Cutting tip
Height Adjustment Screw For Tool Holder & Tool

22. Cutting Tools – Carbide Inserting Tooling
Lathe Fundamentals
Monday, April 24, 2017
Cutting Tools – Carbide Inserting Tooling
Shops also use replaceable cutting inserts.
Cutting inserts come in a variety of shapes, as you can see below.
Inserts are secured in a tool holder and rotated so that there is a new cutting surface in the same location.

23. Lathe - Operations Changing the chuck & collet use Facing Turning
Lathe Fundamentals
Monday, April 24, 2017
Lathe - Operations
Changing the chuck & collet use
Facing
Turning
Center Drilling
Boring
Taper Turning
Parting – Grooving
Drilling
Hole Tapping
Knurling
Threading – using a die and holder
Reaming
Tapered
Faced
Turned
Parted
Necked

24. Lathe - Operations Outer Diameter Cutting Operations
Lathe Fundamentals
Monday, April 24, 2017
Lathe - Operations
Outer Diameter Cutting Operations
Outer-diameter operations are cutting operations that occur on the outer surface of the workpiece.
Facing - is the machining of a flat surface on the end, or face, of a workpiece. Facing is sometimes used to remove uneven, rough surfaces and burrs from a workpiece.
Turning is the machining of the external surface of round parts. During turning, a part is held at one or both ends while it rotates against a single-point tool. The cutting edge is forced against the surface of the workpiece, cutting metal as the tool is fed along the surface.

25. Lathe - Operations Outer Diameter Cutting Operations
Lathe Fundamentals
Monday, April 24, 2017
Lathe - Operations
Outer Diameter Cutting Operations
Parting - also called cutting off, involves separating a complete piece from stock. Parting is important because you can ruin the whole job if the part is not cleanly removed.
OD grooving is a simple machining process during which a cutting tool is plunged into a workpiece to create a groove or channel. There are essentially three types of grooves: square-cut grooves, round-cut grooves, and V-cut grooves.
OD threading - is a special turning operation that uses a single-point tool to cut spiraling ridges (threads) down the length of a workpiece. These threads are found on screws, bolts, and other types of fasteners. The lathe has the ability to cut many different types of threads with the most common being a 60 degree thread.

26. Lathe - Operations Inner Diameter Cutting Operations
Lathe Fundamentals
Monday, April 24, 2017
Lathe - Operations
Inner Diameter Cutting Operations
Lathes are also capable of performing cutting operations on the inner surface of a workpiece. Inner-diameter operations (ID) hold the workpiece on one end, while the cutting tool enters the workpiece at the other end.
Drilling simply creates a hole in the workpiece. A drilled hole is the least accurate type of hole made.
Boring enlarges the inner diameter of a preexisting hole. This process improves the accuracy of the hole and makes it more round. On the lathe, boring is essentially like internal turning.

27. Lathe - Operations Inner Diameter Cutting Operations
Lathe Fundamentals
Monday, April 24, 2017
Lathe - Operations
Inner Diameter Cutting Operations
Reaming smoothes the internal surface of a hole. It uses a special multi-point tool to remove metal from inside a hole. Reaming only removes small amounts of metal. An accurate method of finishing a specific hole diameter.
Tapping cuts internal threads into a drilled hole.
ID grooving cuts a single circular channel or groove into a drilled hole.