Abstract: A sheet metal corrugating apparatus provided with novel upper and lower corrugating die shoe assemblies which can simultaneously corrugate all corrugations in a single piece of relatively thick steel sheet to produce a relatively flat corrugated sheet within prescribed dimensional tolerances. Each of the novel upper and lower die shoe assemblies include a plurality of individually shiftable corrugating dies mounted upon a primary bed member in such a manner that they can shift towards and away from each other, guide bars fixedly mounted on the primary bed member between the corrugating dies, and springs extending between the guide bars and shiftable dies and which bias the corrugating dies apart to their greatest extent when the die shoe assemblies are in their open position.