to thread the hole with full threads up to the bottom
to start the threads
after the first (rougher) tap
to form the threads easily
45 Degree to the centre line of the file
60 Degree to the centre line of the file
75 Degree to the centre line of the file
80 Degree to the centre line of the file
Parallel reamer
Adjustable reamer
Expansion reamer
Chucking reamer
A short reamer with an axial hole used an arbor or mandrel is called as chucking reamer.
H.S.S.
Carbide steel
Diamond
Cast steel
Eye level
Shoulder level
Elbow level
Arm level