Diameter calculation method
Addendum circle diameter=(number of teeth plus 2ha)modulus
Diameter of index circle = number of teeth modulus
Tooth root circle diameter=(number of teeth-2ha-2hc)modulus
For standard gears: ha=1,hc=0.25; other non-standard gears take another
For example: M4, tooth 32
Addendum circle diameter=(32 plus 21)4=136mm
Index circle diameter=324=128mm
Tooth root circle diameter=(32-21-20.25) 4=118mm
This calculation method applies to all modular gears (excluding shift gears).
The modulus represents the size of the gear teeth.
Gear modulus = index circle diameter ÷ number of teeth
Gear module selection
The national standard for gear module is GB1357-78.
Preferred modulus: {{0}}.1mm, 0.12mm, 0.15mm, 0.2mm, {{10}}.25mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.8mm, 1mm, 1.25mm, 1.5mm, 2mm, 2.5mm, 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 20mm, 25mm, 32mm, 40mm, 50mm;
Optional modules: 1.75mm, 2.25mm, 2.75mm, 3.5mm, 4.5mm, 5.5mm, 7mm, 9mm, 14mm, 18mm, 22mm, 28mm, 36mm, 45mm;
Rarely used modulus: 3.25mm, 3.75mm, 6.5mm, 11mm, 30mm;
