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Sheet Metal Talk - spiral handrail

tintailoruk - Mar 10, 2008 - 02:39 AM
Post subject: spiral handrail

could somebody please tell me if I am correct in my assumption that a handrail for a spiral staicase, can be developed using the same principle as an ellipse of a cylinder being cut at say 45 degrees, but only using a quarter of the plan of the ellipse ie the developed radius of the ellipse and the rise, sorry if it is a bit vague but I have no sketch to hand but if anyone can suggest I will try and make a diagram to clarify, thanking you on anticipitation

bordontn2 - Mar 10, 2008 - 06:11 PM
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tintailoruk
you're looking for the hypotenuse of a right angle ..base being the circumferance of width.. square this / rise squared /add together/find the square root..
That will be the length of your rail
base x pi squared/ hgth squared /add together/ square root of total equals
length of rail ( 360°) one turn........
bordontn2

tintailoruk - Mar 11, 2008 - 01:25 AM
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thanks bordontn2, yes I am aware of that but what I wanted to try and explain is the, well can I say the correct curve is what I wanted to establish, obviously you would not roll a section of to the true radius ie the centre of post to inside of the handrail, you have to allow for the slope of the 45 degree angle this then becomes the part of ellipse, sorry I am not trying to be a smart ass I really do not know and I really do not want to waste or scrap the material I have bought for the job ie 2inch x 1inch rectangular s.s tubing, I have a friendly company with power rollers to roll the section and I am considering to screw the section to the spindles of the staircase, alas I have no Tig welding machine ,

MattM - Mar 11, 2008 - 02:28 AM
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Considering you can roll a strip of metal into a pipe - think of the paper tubes for wrapping paper - I'd say your diameter is dependent on the slope you hold the piece as you roll it. If you go 45º angle then it would seem awfully steep for a spiral staircase, but you have the right general idea.

bordontn2 - Mar 11, 2008 - 03:05 AM
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tintailoruk....it wouldn't be an ellipse, it would be a helix...if it was an ellipse it would go 1/2 way up then return down..You would never get upstairs.............make yourself a scale model w/some wire.the diameter is what it is.The diameter won't change..
frenstance..a 48" diameter staircase w/ 45° rise ...circ.at 48"=150.8" the true length would be 158.25" Roll it w/24" radius..
The ends will overlap 7.45"..Stand on one end and pull up 48"..Or connect one end pulling vertically as you fasten to your spindles.
Not a smart--s either..Make a model..
bordontn2

tintailoruk - Mar 11, 2008 - 09:54 PM
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bordontn and Mattm, sorry guys I had my Brazil head on and did not pay attention, yes you are both correct I was looking at the problem too deeply, sorry for making a fuss, it has dawned onto me now, I have every cofidence now to go ahead with the rolling, again thanks to both of you, you have stiffened my resolve now, (resolve! nothing else lol), I was looking at to pre drill the handrail prior to rolling and if you are interested I will let you know the results of the holes picking up with the spindles

bordontn2 - Mar 12, 2008 - 02:42 AM
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tintailoruk ..............good to have you aboard. post a picture when you build it ...challenges & opportunities, that's what we like
We don't mind a fuss..Just glad to help. Sometimes you can't see the forest for the trees....
bordontn2