Specifications of the front hub:    
Brand:    Shimano
Model:    DH-C3000-3N-NT 6V-3.0W Dynamo
Color:    Silver
Number of spoke holes:    36GTS
Type of brake:    Rim brake
Type of axle:    Fixed axle 140 MM
Axle included:    Yes, with nuts
Type of bearings:    Ball bearings
Average weight (GR):    705
Intended use:    City
    
Data for spoke length calculations using the Sapim spoke size calculator:    
Total length of the hub (MM):    100
Non-gear side (MM):    19
Gear side (MM):    20
Hub diameter non-gear side (MM):    74
Hub diameter gear side (MM):    74
    
Link to spoke calculator: www.sapim.be/spoke-calculator