I also posted this in the metalworking forum..
After spending too much time trying to find plans for a spiral staircase, or a kit for a reasonable cost, I've decided to start from scratch and make my own. What I plan to do is weld 4" angle iron "tread brackets" to a 3" pipe at 30 degree spacing (all material is 1/8 inch). Each tread is 8 " higher than the next one - this gives 11 treads for an 88 inch rise. I'll cut a 1
1/2" radius curve into the horizontal part of the angle iron to match the pipe I'm welding it to. The tread brackets will have welds on both sides of the vertical and horizontal surfaces. Then I'm going to drill and bolt 2 by 12 wooden tread to each bracket. Brackets will probably be 36 to 40" long as will wooden treads. I still haven't figured out the balusters, but probably will use a single rod welded to each tread bracket and somehow curve a metal railing for a hand rail (the rail will be a problem). This may sound like a lot of work, but I have all the materials on hand, a Miller 175 MIG welder and a plasma cutter. There are only 11 treads to attach, so I can get this part cut and done in a day, provided I can layout the degree spacing without botching it. The big problem I see is the railing, but I do have a small bender which I could bend short sections of pip in, and weld them together as I work my way up. I looked for kits, and none had wooden treads for less than about $2500 shipped to me in Colorado, so I have some financial incentive. Any help would be much appreciated. Thanks for being a great group.John