[delraydella]

Anyone here ever build a spiral staircase? I might do one and I'm thinking of using steel tube for the railing. So my question is...what's the best way to lay out and fabricate that spiral? Would it be best to roll the tube to the spiral and weld it into place, or to start out with a straight piece of tube, weld it to the first baluster, heat it up and force it into position on the next baluster and keep working up? Or any other way to do that?

[sparkness]

I would roll the tube and then un coil it to your total rise . like wrapping a wire around a pipe then stretching it out, it may not be that easy though . check with local steel suppliers they may have power tube roller that can be used. Check you tube

[TRACKRANGER]

Definitely needs to be rolled if you are looking for any sort of reasonable finish. I doubt you will be able to achieve a smooth spiral with a weld, heat, bend, weld, heat, bend approach.

If your total rise is more than one full turn, you might be able to get two part circles rolled and join them to get the distance you require. Remember that as you stretch, the effective diameter will decrease.

HTH, Trev

[Otto Nobedder]

Yep, the math on this is mind boggling.

You know the diameter of the staircase, but you can't have your handrail rolled to that diameter, because you have to factor in the rise/run of the steps.

This is one thing I've not tried, so I'll not offer untested advice.

You do have me curious, though.

Don't be surprised if TamJeff doesn't chime in with a dirt-simple way to figure it...

Steve S

[weldin mike 27]

Don't you mean "the aluminum yoda"

Mick

[delraydella]

but that's who I need!

I know when you roll tube through a hydraulic roller, it has a tendency to want to spiral up as it comes out, but could that be controlled to give me the spiral I'd need?

And I agree, rolling it would look the best.

[weldin mike 27]

http://www.superiorspiralstairs.com/layout-guides.php maybe this

[GlenC]

Formula:
Circumference = 2πr
h = (height of helix x 360) / angle
Length = √(h^2 + circumference^2)
Unit Rise = h / circumference
Handrail Radius = (4π^2r^2 + h^2) / 4π^2r
where:

π = 3.1415926
r = Radius
h = Height required for Helix to complete one revolution

[weldin mike 27]

Head = Exploded. Straight staircase is looking pretty good to me.

Mick

[MinnesotaDave]

I just saw one that did the "heat-bend-heat" method in a house that I'll be making some iron work for.

It looks "ok" until a person stands at the top and looks down - then the bends are very obvious.

If I had to redneck one - I'd figure my length using a triangle method (Pythagoras) since I like it better than the formulas, then put a decent bend in it with a roller while while making sure it came off the roller in a direction that caused the nice helix effect.

Triangles because if I figure the outer diameter as a tube, then unroll it flat, the helix becomes the hypotenuse of a right triangle.

This is why the helix formula has the square root of two squared terms in it - basically sqrt(a^2 + b^2) = c where c is the length.

Then I'd heat and adjust on the way up. Much easier to work with a partially correct bend than a straight pipe.
But this is only if I was red-necking it.
If it had to be perfect, I'd do more math for my bending set-up so the off-set upon exiting the rollers was correct.

[delraydella]

Thanks!!!

Guess I gotta take some measurements now...

And Mick, you're right, a straight staircase is always much better, but me and my big mouth.
'" A circular staircase would look really nice there. Can you make me one?"
"Of course, honey!"

Other Steve

[dsmabe]

Id say bend the pipe into a coil then stretch vertical. Then build the staircase to the handrail instead of building a handrail for a staircase.

[Jacked800]

I like this thread. Keeps the mind going.

What you've got to remember is when you stretch the coil vertical it's going to pull the diameter inwards. Like when you pull too far on a spring. So the trick is finding the right diameter to start with so your finished diameter ends up fairly close.
Building motorcycle frames trying to experiment bending 1 1/4" DOM tubing gets a little pricey, so someone came up with the idea of using EMT (electrical conduit) which fit pretty well in a JD2 die.
I imagine it would also fit in a roller too. Be a cheap way to practice.

What you have is a compound radius. You are going around and up at the same time. You almost need to push it through a roller one time, and turn it as you do it to give you the rise you would have in one complete revolution.
I would guess that you'll have about 30" of your outside radius between each 8" of rise. (just saying) Think I could figure it out if I had exact measurements of the stair treads, total diameter, and the rise of the treads.

THANKS Jack