Calculate the pressure angle of dividing cylinder, base cylinder and pitch cylinder, normal surface and end pitch circle of gear

① Spiral angle of two gears:



② Two gear indexing cylinder helix angle:

③ Two gear base cylinder helix angles:

④ Helical angle of two gear segments:

⑤ Pressure angle of normal pitch circle of two gears:

⑥ Pressure angle of end pitch circle of two gears: