spiral staircases; how to?

I've seen pictures of the 'pros' doing it for a steel stair case manufacturer. Sets it up on the floor, uses a 'hicky' bender, and just has at it. A hicky bender is nothing more than a short shoe the size of the pipe, a hook on the back side, and a long handle. Hook and bend the pipe no more than a couple of degrees. Get a new grip and do it again. For the spiral, you need to do the bend then twist the pipe a bit for each new bite. It's 3 dimensional and very tricky to get it right.

The other > would like to try my hand at a building a spiral staircase.

You can get the pipe rolled to the correct arc if it is too heavy to pull into position. You will have to calculate the arc. Larger commercial tube bending outfits so this regularly and if you give them the outside diameter of the stair rail, total rise and total run on the circumference they can get it pretty close. They roll the helix for you. I have worked with eight inch channel rolled to become the inside and outside stringers. We only had to do a small amount of tweaking to get the two stringers matching. In less than two hours we were ready to install our preformed treads Randy

Be sure and give some thought to how you're going to get the helix into place if you have it done in one piece. Imagine yourself trying to drive a 12 foot long screw down into the upper floor. Do you have the necessary clearance above?

Of course if your stairs are steep enough that you have less than one full turn, or even slightly more than one this won't be such a problem, but it's worth thinking about _before_ you start.

Al Moore

prices seem to be cheaper for a 'hoop' rather than having a shop form the spiral/helix. i'm wondering: if i have two circles bent, can i cut them and weld them into a helix shape?

i'm having a hard time visualizing whether or not this would create 'kinks' in the tube where the welds are. by 'kink' i mean discontinuity in the curve. maybe i could cut a hoop into thirds (or more), instead of halves, and weld them up in a helix shape without losing the 'flow'?

any thoughts on this approach? i realize the original hoop would have to be a larger radius than the finished staircase, as pulling it into a spiral would tighten it.

this would also help me around the problem Alan brought up re: installation.

-tony

I am asked about doing spiral stairs about twice a year. I always refer people to the 2 shops in the Seattle are that do nothing but spirals. I am happy to do the assembly and install, but I have them fabricate all the parts in advance. Much easier.

The only tricky part is the actual grip rail. Have you thought about not using a single tube for the handrail. Instead use a bundle of smaller rods or tubes.

1/2" or 3/8" rod would work fine. Just build you stair with t he treads welded in place around the center tube. Attach the hand rail support tubes to each tread. Then just play connect the dots with the smaller rod, tacking to each support as you go. Then just repeat the operation with another, and again and again. It should allow a very even curve, and will give an interesting visual effect to the hand rail.

We used to build trees that way at the Seattle Opera Shop using steel hydraulic tube.

Nope; if you want a helix you need to make the curve consistent. You *could* make a multi- turn coil in a plane (pushing previous segments aside as new ones were formed) and then pull it out like a spring. That would give a constant curve for the helix, but might leave you with unacceptable stresses in the final product.

If your tube is fairly stiff (likely in a spiral staircase) then you need to find someone who can put the proper offset in each turn. This isn't something new; helixes are used for a lot of purposes, so someone out there can do what you want.

-- --Pete "Peter W. Meek"

My dad and I built a spiral staircase for a house I used to own. We first welded the treads onto the center support. For the handrail, we used pipe. We tacked one end of the pipe directly to the outside of the bottom tread (Call it "A"). Used a couple rosebuds and a hand pipe bender to form the curve to the next tread up (Call it "B"). With the pipe hot, you can adjust the curve by eye to be pretty fair. When we got it right, we tacked it to tread B and repeated heating and bending to tread "C" etc. This forms a spiral that is already "threaded" onto the staircase and has exactly the right pitch. After the rail was formed, we cut the tacks, welded the supports to the treads and the completed rail to the supports. Turned out pretty well. Not perfect, but most non-fabricators would never notice.... ;-)

-- Greg snipped-for-privacy@depmco.com

That's an amazingly innovative way to make what is required for a given staircase. One of those 'why didn't I think of that' moments!

Jim

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