What method is used to develop patterns for square-to-round fittings?

The method used to develop patterns for square-to-round fittings is triangulation. This approach is particularly effective for creating templates for geometric shapes when transitioning between different configurations, such as from a square to a round ductwork shape.

Triangulation involves dividing the fitting into triangular sections that can be easily measured and calculated. By using known dimensions, such as the sizes of the square and round ends, the triangles can be constructed to determine the length and angles needed for the pattern. This results in an accurate flat pattern that can be used to fabricate the fitting from sheet metal.

Other methods, while useful for different types of ductwork or fittings, do not specifically address the unique transition from square to round as effectively as triangulation. Radial line development, for instance, is suitable for circular shapes and complex geometries but does not directly apply to square-to-round transitions. Similarly, parallel line development is best for patterns that do not require angle changes, making it less relevant for this particular fitting shape. Cross triangulation integrates some similar principles but is used for specific cases where the geometry requires it. Each method has its specific applications, but for square-to-round fitting patterns, triangulation is the most appropriate choice.