A.2/3~3/4 B.1/2~3/4 C.1/3~1/2 D.1/5~1/2
A.0.01~0.03mm B.0.01~0.05mm C.0.10~0.20mm D.0.10~0.30mm
A.前角 B.正前角 C.負(fù)前角 D.后角