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Up Topic Welding Industry / Welding Fundamentals / Spiral staircase update
- - By aevald (*****) Date 04-23-2008 04:28
Hello everyone, quite a while back I posted a classroom aide that was modeled to help explain spiral staircases and some of their lay-out issues and methods. At that time someone asked me about the handrail; well I finally did something about the handrail, but not before I did some "heavy" research(for me), to determine the formula for determining the starting size for the handrail helix. I had a home-brew type of formula that would get close but it still wasn't quite right, after checking on the internet some I found a couple of sources for much better information and what follows is a first attempt at providing an applicable method. The "pitch" that is referenced in the formula is the height of one 360 degree turn of the rail and the "inside radius" that is referred to in the formula is the number that is representative of the finished inside radius of the rail. The "Answer" that is arrived at by dividing "Product 1" by "Product 2" is the inside radius used to layout the rail section in it's flat condition before stretching. I hope this makes sense, if not please help out with any comments for something more user friendly. Best regards, Allan
Attachment: DIFFERENTIALGEOMETRYTODETERMINEHELICALHANDRAILANDAUGERFLIGHTS.doc (64k)
Parent - By rlitman (***) Date 04-23-2008 06:05
Makes sense to me.  Also, you could make auger flights with this formula.
Parent - - By bozaktwo1 (***) Date 04-24-2008 16:58
Awesome.  More math than I like, but awesome.  Nice job.
Parent - - By aevald (*****) Date 04-24-2008 18:36
Hello Curt, I certainly agree on the math part..... and that's partly why I wanted to include this information. I believe this is as simple as it gets, yet, I probably haven't quite got it organized into a completely understandable manner. Thus, it is a work in progress and hopefully I'll get it refined to the point where it is readily and easily understood. Best regards, Allan
Parent - - By RGL (*) Date 05-01-2008 02:27
Aevald, when the hand rail is pulled to the correct height from the "calculated" diameter will it give you 360 degree's of coverage to the actual diameter as it appears in the photo's. I don't see any welds on the handrail and it looks like it made the complete 360 degrees, after it was pulled, or does it just look like 360?     RGL
Parent - By aevald (*****) Date 05-01-2008 03:56
Hello RGL, when all the calculations are completed and you have "pulled" it to the appropriate height, it will actually exceed the 360 degrees of rotation by quite a bit. How much is really dependent upon the stair angle. When I have a little bit more time and access to my calculations I will try to figure exactly how much, but it will vary with different situations. Best regards, Allan
Parent - By aevald (*****) Date 05-01-2008 15:21
Hello again RGL, I went through the numbers on this and this is what I came up with; the O.D. for the spiral comes out to approx. 22 1/2" for the spiral, the actual O.D. of the stair rail when stretched is 17 11/16", figuring a 360 degree turn for this using the 22 1/2" part stretched yields approx. a 98 degree excess on the finished stretched piece. Hope this is what you were asking. Best regards, Allan
Up Topic Welding Industry / Welding Fundamentals / Spiral staircase update

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