Board section

In the graphical representation of a multiply curved vane in plan projection, the board section is a contour line whose geometric elevation above an arbitrarily selected reference level is measured perpendicularly to the pump shaft.

To make the board section, the pattern maker cuts out a number of small boards of 5 to 10 mm thickness made of wood, plastic or another suitable material in the shape of the contour lines shown on the drawings, and glues all the boards together in accordance with the contour line drawing (board section representation) to obtain the pattern of a vane surface after filling out or grinding down the step-like shoulders (projections).

The plan projection representation of an impeller in board section form is very useful for checking the smooth and continuous pattern of a vane surface. Even in vane surface manufacturing methods such as numerically controlled milling (NC milling), the board section still plays an important role.