I made this spiral staircase for my loft in Boston. I used my X-Carve CNC machine by Inventables.com to cut out the initial pieces. In the interest of time I had a friend use his machine which has a large bed cut out some of the pieces. Each step is made out of 12 layers of ¾” furniture grade plywood. You can download the dwg drawings that we used here.

The stair case is 16 and ¾ steps tall and is built around a 3” schedule 40 steel pipe. The steps are the same but each one is rotated 30 degrees with 12 steps creates a full revolution around the pole. I mistakenly assumed that the ¾” plywood I was using was was exactly ¾” thick and my steps ended up being about half an inch shorter than I intended but it all worked out. I thought that keeping the stairs aligned was going to be a bigger challenge than it was so I had the CNC drill perfectly aligned holes for ½” dowels. I ended up not using these holes since it was easy enough to just to align the edges and clamp the boards.