A skilled pattern maker builds a pattern of the object, from the drawing, provided by designer by using wood or metal.
After making pattern it is checked thoroughly for the following parameters. Diameter of propeller, Profile of blade, Pitch at all radius i.e. 0.2 R to 0.9 R, Thickness of blades at various points, at the maximum thickness point at various radii as well as at the 20%, 40%, 60%, 80% of chord length at both side of maximum thickness line.
Then pattern is released for production to foundry.
For traceability of pattern, on pattern following
markings are made
i) Pattern No.
ii) Party’s Name,
iii) Diameter of Propeller,
vi) Pitch of Propeller,
v) BAR of Propeller