Lesson 1 Introduction to the Lathe
In earlier modules, we learned the names and uses of many small hand tools and measuring instruments. Now, we want to begin studying large machine tools that every machinist should know about.
What is a machine tool? It’s a large tool that is powered by an electric motor and is used for making parts. Some examples are lathes, mills, and grinders.
In this module, we are beginning study of machine tools by looking at lathes.
Word List
| lathe |
a machine tool that makes round parts by removing material from a rotating workpiece. e.g. It is important to be safe when working with a lathe. |
| to mill |
to shape a stationary workpiece by the use of rotating cutters. e.g. Raul milled a new gear in less than a half hour. |
| to grind |
to remove material from the surface of a workpiece by the use of abrasives. e.g. Aluminum oxide is the most common and best material for many grinding jobs. Parts: grind, ground, ground. |
| to shape |
to give form toa a workpiece by cutting, grinding, or some other process. e.g. Martina shaped the part on her lathe. |
| round work |
any workpiece that is round. E.g. A piece of round work could be cylindrical or tapered. Related word: round stock = any piece of rough stock that is round. |
| turret |
a block holding several cutting tools which can be turned to present any of the tools to the work. e.g. The lathe was equipped with a turret which held four cutting tools. |
| sequence |
the following of one thing after another in a planned order. e.g. making any part usually requires a sequence of carefully done procedures. |
| to punch |
to make a hole in the something by pressing down with a round cutter. e.g. As we got on the bus, the driver punched each of our tickets. |
| tape |
a long, thin strip of paper, cloth, or plastic. e.g. some lathes are controlled by long rolls of punched paper tape. |
| swing |
the largest diameter of a piece of round stock that will fit into a particular lathe. e.g. the size of a lathe is measured by its swing. |
| lathe center |
a support that is placed at one or both ends of the rotating workpiece. e.g. Arnold mounted the round stock between two lathe centers. |
| axis |
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| to fly out |
to move away rapidly from a center through the air. e.g. Jorge was injured when a chip flew out from the lathe and hit his unprotected eye. Parts: fly, flew, flown. |
a real or imaginary straight line around which something rotates. e.g. The Earth rotates around an imaginary line called its axis.
Ex. Spelling Practice
Ex. Past Tense Review: Regular and Irregular Verbs
Changing from the Present to the Past.
Most verbs (action words) form their past time by adding “-ed” to the end of the present time. e.g., love becomes loved.
However, some verbs are irregular; they form their past by other letter changes. E.g., grind becomes ground and fly becomes flew.
Ex. Complete the Sentences
INTRODUCTION TO THE LATHE
In this module we will learn about the first of the large machine tools, the lathe. Other large machine tools include: drilling machines, milling machines, metal cutting saws, borers, and grinders.
1. Purpose of the lathe: The main purpose of the lathe is to shape and finish round work. A lathe can produce round work like screws, shafts, cylindrical parts, and tapered parts. Among the operations that a lathe can do on a round workpiece are: turning, tapering, threading, facing, drilling, boring, grinding, and polishing.
2. How the lathe works: A piece of round stock is held by the lathe, and the work is rotated on its axis at a rapid speed; the work piece is cut, shaped, or ground by a variety of tools which are slowly moved against and along the workpiece and which remove the material from the spinning work.
3. Kind of lathes:
a. The engine lathe: This is the common kind which is found in small machine shop and in schools. It is the kind we will spend our time studying. It is not used for mass production of many parts, but for small jobs where a lesser number of parts is needed.
b. The turret lathe: This lathe is used for mass producing parts. It has a turret with different cutting tools on it; the tools can be set to cut the workpiece at different times in a sequence of steps. This can be done over and over to produce many identical parts.
c. Computerized numerically controlled lathes: These lathes are used in production sites to mass produce parts. The operations of these machines are controlled by a punched tape or a computer.
d. Turning centers: These lathes combine several operations in one central machine; they can be computer controlled and use more tools than the turret lathe.
4. The size and capacity of Lathes:
a. The size of a lathe is measured by the diameter of the round workpiece which the lathe can rotate around the central axis; the diameter is called the swing. Nine to thirty-inch swings are common sized for engine lathes.
b. The capacity of a lathe is measured by the distance between the two centers which hold the two ends of the workpiece. The distance between centers for an engine lathe can be between 16 inches to 12 feet.
A common engine lathe might have a swing of 13 inches and a capacity of 36 inches. The lathe itself might be 6 feet long.
Ex. Spelling and Identification
Ex. Lathes–Their Size and Capacity
Ex. Comprehension Check
Complete the Sentences
Lathe Parts Identification
THE MACHINISTS TALK ABOUT SAFETY
Conversation No. 1:
Isidro, a new worker, is talking to Alejandro, an experienced machinist, near the lathe.
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Isidro: |
Alejandro, will you show me how to run this lathe? |
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Alejandro: |
I’ll be glad to, but this is your week in the shop. Before we turn the machine on, we need to remember some things about safety. |
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Isidro: |
Oh, yes, I’ve got my safety glasses here, and I’ll put them on before we start. |
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Alejandro: |
That’s right. The lathe spins the work very fast, and a piece of metal could come flying out. We need to protect our eyes. |
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Conversation No. 2:
Isidro and Alejandro continue their conversation on safety around the lathe.
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Alejandro: |
Let me tell you some more about lathe safety. Do you see all those metal chips on the machine and on the floor? |
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Isidro: |
Yes, they were cut from the workpiece during the last job. |
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Alejandro: |
Yes, and whoever was working here should have cleaned them up. Let’s do that now, before we start. You always want a clean work area – the chips cleaned up, and no chemicals or oil on the floor. |
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Isidro: |
All right, I’ll get the brush to get the chips off the machine. |
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Alejandro: |
Good. I see you know not to use your hands or a cloth. You can cut or puncture your hands. |
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Isidro: |
Why can’t we use a cloth? |
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Alejandro: |
Because small chips and pieces of metal can become imbedded in the cloth and they’ll cut you too. |
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