Vlnitý plech (1,0 x 0,33)

The corrugation, its depth and one constant number

A polystyrene sheet 15 x 30 cm with a transverse waveform. The corrugation spacing is 1.0 mm, the depth 0.33 mm, and both numbers are given in the name.

What is interesting is that the ratio of the two values stays the same across the whole series. The finest sheet has 0.25 mm of depth to 0.75 mm of spacing, the coarsest 1.13 to 3.2, and every intermediate step keeps to around one third. Corrugated sheet metal is profiled so that the corrugation gives the panel stiffness, and that stiffness is derived from the ratio of depth to spacing. When a modeler reaches for a sheet with a different ratio, the metal looks either like cardboard or like roofing made of corrugations the size of a gutter.

The absolute size is then straightforward. The most common corrugated sheet metal has a spacing of seventy-six millimeters, that is three inches. Seventy-six divided by one millimeter gives one to seventy-six, which is separated from one to seventy-two by a difference nobody can measure. A depth of 0.33 mm corresponds in the same reduction to twenty-four millimeters, and that is a real corrugation height.

When building shelters and fences it pays to wave the sheet slightly before gluing and to add a bent corner. Flat corrugated metal barely exists in reality.

The detail that sells the surface is nails with washers. Real corrugated sheet metal is nailed into the crests of the corrugations, never into their bottoms, so that water cannot get in, and the heads therefore form regular rows along the tops. It is enough to suggest them with the point of a needle from the face side and, once painted, to emphasize them with a dark dot with rust holding around it. Place the rows near the edges of the panel and at the places where two sheets overlap, because that is exactly where the metal is anchored.