1. Countersinking ,boring, counterboring,reaming,tapping
Drilling operation
Combine operation
Complex process
Countersinking ,boring, counterboring,reaming,tapping

2. COUNTERSINKING OPERATION
 tapering or bevelling of the end of a hole
 conical cutter
form recesses for flathead screws
 speed approximately one-half of the speed for the same size drill.
Feed should be light, but not too light to cause chatter.

3. COUNTERBORING enlarge the upper end of a hole
 recess socket head cap screws
standard counter bore cutters.
 0.002 to inch per revolution,

4. TAPPING OPERATION cutting a thread in a drilled hole
The tap drill size  FROM TABLE.
Two method of tapping
Hand method for large holes
Gear method for small holes

5. REAMING OPERATION Sharp edges the holes are first drilled
slightly undersized
hand reamer or using a machine reamer 
 slight chamfer
High accuracy finishing

6. HAND REAMERS used when a greater accuracy in hole size is required
 taper which extends 3/8- to 1/2- inch above Chamfer
metal to be removed by the reamer, from to inch
Never  used for power

7. MACHINE REAMER taper shanks to fit the machine spindle.
good clean holes.
Available in1/64 inch for reamers l/2-inch to 1 inch in diameter.
Smooth reaming.
Coolant is used.

8. Boring operation
Enlarge the given drill hole