
Use the following
AUTOCAD command:
1. circle
2. offset
3. extrude
4. line
5. subtract
Method: 1.Draw a
circle with the radius value of
50mm whereas the thickness value is about
5mm offset.
2.Switch the current view into
SW isometric then create a straight line about
400mm directly to the center point of a
circle.

3.To begin the extrusion of an object enter the command
extrude then select the
two circle followed by typing the word
Path. Currently select the
line or what we called the
extrusion path then press the enter key to see the result.

4.Use
shade command to hide from view of
isoline. 
5.Take away the unnecessary objects. Use the command
subtract:


6. then press
ENTER.
7. select
solids and
regions to subtract.

8. Finally press the key
ENTERRESULT