Developing Hoppers and Chutes

Developing Hoppers and Chutes

A hopper is a truncated pyramid or cone, usually inverted, that funnels material into a smaller outlet. CAPS names it specifically because it combines several development skills in one practical object.

A rectangular hopper is a truncated pyramid. Develop the full pyramid, mark the truncation on each generator using true lengths, and remove the top. The four corner edges are the ones needing rotation — the mid-face slant heights are not the same measurement.

A conical hopper is a truncated cone: the sector development with the cut arc marked on it.

Chutes add a further complication: the inlet and outlet are often at different angles, so the piece becomes a transition and must be triangulated rather than developed as a simple truncated solid.

The wear consideration. A hopper's steepest face wears fastest because material slides against it. Fabricators often make that panel thicker or replaceable, which means the development must be split so that panel is a separate piece.

Worked example. A square-to-square hopper reducing 600 mm to 200 mm over 400 mm depth: four identical trapezoidal panels, each needing the true length of its sloping edges, not the depth of 400 mm.

Core checkpoint: A hopper is a truncated solid. Develop the whole solid, then mark the truncation with true lengths.