tech EX PO 2005 Modular Spiral Step Unit by Jim Ream University of Indianapolis For an outstanding but long-forgotten production at the University of Indianapolis we needed a spiral staircase. We decided to build stock modular units that folded for storage and could be assembled in various directions of rotation and heights. Our first set of these step units proved more useful than we had anticipated. They served as quick, freestanding escape stairs for dozens of productions, and helped mitigate space limitations on stage and in storage. We recently built a new set of these stairs, with some improvements to speed assembly and to make them lighter in weight. Design Criteria Most of our stock steps are 8˝ rise. We decided that a 4´ radius step would be the most useful and would provide adequate tread depth in the center of the unit, which is where most people step (fig. 1). Construction Details Each unit consists of a pie-shaped support, hinged to fold, similar to a parallel platform frame. The supports are w BC plywood with portions removed below 8˝ to reduce weight and provide convenient access for clamps for quick assembly. Each step is a free-standing unit and can be used by itself or in combination with other units to create varied heights and directions of rotation. One or more sets can be stacked on platforms to reach higher elevations. Figure 2 is an example of a design that used three sets of steps on two platforms to reach a balcony despite limited floor space. A set of four steps built from w˝ plywood weighs approximately 130 pounds. Two sets can be stacked and stored in a space 16˝ wide by 52˝ high. ▼ Figure 1 Materials List * For one set of 4 steps * 8˝ rise per step Item 3 sheets w˝ BC plywood 16´ 1x2 (ripped from #2-1x4) 16´ 1x4 32 hinges with screws Glue and assorted screws Total Cost 22 S P R I N G 2 0 0 5 Cost $78-$126 $2.92 $5.84 $43.00 $10.00 $140-$190 TD & T ...stock modular units that folded for storage and could be assembled in various directions of rotation and heights.