Technology and our changing world high Technology

TURNING BETWEEN CENTERS ON THE LATHE
A workpiece can be fastened between the headstock spindle (live cente and the tailstock (dead center) of the lathe. It can then be turned against a cutting tool mounted on the post. This is called turning between centers. For
the workpiece to be held securely by the centers, it must have shallow holes drilled in both ends into whish lhe centerswill fit.
Select the stock for the workpiece. The stock should be about %” longer than the finished size id to be. This will allow for the ho les that will be drilled in both ends. After the turning has been finished, the extra length and holes may be cut away if necessary.
The stock should also be about '/₈”larger in diameter than lhe finished size. This will allow for the metal that will beremoved by the cutting tool.


Finish turning
Adjust the lathe for a slightly higher speed and faster feed, and a shallower depth of cut. Finishes turn the first half. Adjust the caliper to the diameter the work should be when finished and check the workpiece. If correct, place a soft collar of copper or brass undo‘ lhe lathe dog. Then reserve the workpiece, and finish turn the second half. The soft collar will protect the first half from marring.


Filing and Polishing
To file on a lathe, place the work between centers, and adjust the lathe to high speed. Use a long angle lathe file. Hold it firmly in your hands and make long, even strokes. Keep the file clean. To polish a surface, hold fine abrasive clolh on themetai. Apply a little oil for better cutting.
Other Lathe Operations
The lathe can also be used with a three-jaw chuck mounted on the headstock. A metal workpiece can be mounted in the chuck, and then turned or drilled. Thread-cutting and knurling, are also done on the lathe.


Review questions

1. 
   Describe thefivebasic machining processes/
   
2. 
   What operations can beperformed on the lathe?
   
3. 
   Describe rough and finish turning.
   
4. 
   What is a lathe dog used for?
   
5. 
   How do you po lish on th e lath e?
   

“TO BE” FE’LINING ISHLATILISHI

“to be”fe’li “bo‘lmoq”ma’nolaridaquyidagihollarda ishlatiladi:

1. 
   Kishilarning kim ekanliklarniko‘rsatishda
   

He is my brother.
She is your sister.
We are friends.
they are my parents.
I am his friends.

2. 
   Kishilarning qanday kasbda ekanliklariniko‘rsatishda.
   

Lola is student.
My brothers are economists.
They aredoctors and nurses.
I am an engineer.

3. 
   Kishilarning narsalarning qanday holatda ekanliklariniko‘rsatishda:
   

He is a sleep.
1 am afraid of dogs.
She is vary tired.
They are not hungry, but they arethirsty.
You are rich. It is hot. It is raining.

4. 
   Odamlar vanarsalarningqayerdaturganliginiko‘rsatishda:
   

He is at school.
We are at home.
Nargiza is at the cinema.
Flowers are in the balcony.
TV-set is in the corner.

5. 
   Yordamchife’lsifatidadavomli zamon yasashdavamajhulyasashda: He is writing a letter.
   

Ob id is driving a car.
I am helping my mother.
The/ arebuilding a new house.
The cup is broken.
My friends are invited.
Lola is spoken about.
This boy is much talked about.

6. 
   Mo d al fe’ 1 “mu st” n in g ekv iv alen ti s ifatid a:
   

I am to go to the library today.
He is to translate this letter.
We are to learn English well.
To befe’lin ing oddiy hozirgizamon shakllari:
am. am-1 shaxs birlik uchun
to be is. is-III shaxsbirlik uchun are. are-boshqashaxslar uchun
To be fe’lin mg oddiy o‘ tgan zamon shakllari:
Was. was-1, III shaxslai^- birlik uchun
to be were. Were- boshqa shaxslar uchun
Bo‘lishli “to be" fe’lining shaxslari tuslanishi

1.1 am.	I. Am I.	I.I am not (I’m not)
11. You are	11. Areyou?	11. You arenot(You aren’t)
III. He is	Il.Ishe?	III. He is not (He isn’t)
She is	Is she?	She is not (She isn’t)
It is	Is it?	It is not(It isn’t)
I. We are	Are we?	We are not (we aren’t)
II. You are	Areyou	Your not (you aren’t)
III. They are	Are the/	They arenot(They aren’t)