In the graphical representation of the multiple curved blades in the plane projection, the plate part is a contour line whose contour line is measured perpendicular to the pump shaft, which is above the arbitrarily selected reference level.
In order to make the wooden board, the pattern maker cuts out many small wooden boards with a thickness of 5 to 10 mm made of wooden boards, plastic or other suitable materials. The shape is as shown in the outline line, and then all the boards are glued on together. Fill or grind the stepped shoulders (protrusions) according to the contour map (board cross section) to obtain the pattern of the blade surface.
The plane projection representation of the impeller in the form of a plate section is very useful for checking the smooth continuous pattern of the blade surface. Even in the blade surface manufacturing method (such as numerical control milling (NC milling)), the wooden board still plays an important role.