Elliptical shaped stair

[cadkiller]

Group;

I'm trying to create an elliptical shaped stair like the picture below.
Any help would be appreciated.
Had problems attaching picture.

[luigi]

It was too quick, you need to attach the picture

[sbrown]

I have created many elliptical stairs and the best way to do it is draft it first using detail or model lines in plan, create 4 center points one for each end and one for the midd section, make arc segments for your boundary lines, then draw lines from those centers radiating out between the boundary lines and array them. Once you stair is drawn, enter the stair tool and draw the boundary lines first(picking your drafted lines), then pick your riser lines)

Finish sketch and you're good to go. One tip instead of picking the boundary lines Pick the first one, then use the tangent arc command to draw the next two this will eliminate the line between the 2 arc segments.

[cadkiller]

Scott;

Thanks for the tips. I wanted to be able to use a true ellipse as the boundry instead of constructing it out of a series of arcs. Is that possible? When I'm in the sketch mode for the stair the ellipse isn't available to create a boundry. Also have tried to sketch out the ellipse before hand and wasn't able to select it as my boundry. Why is this so?

[sbrown]

No and no contractor(maybe there is one) would construct it as a true ellipse, its much easier to layout as 4 arc segments then a true ellipse and you'll never know the diff. If you want sketch your ellipse shape in plan first with the line tool, then trace over it with arcs and you should see the diff. is so slight, its not worth the brain damage to make a true ellipse.

[cadkiller]

Scott;

I just finished a stair job that the architect was so insistant that I follow their true elliptical shape ring beam above the opening that was hammered and forged into a true ellipse. I told them that I couldn't do that for the stair stringers and would have to make as you say with a series of arcs. I am in agreement that the arcs will be close; but to some it may not be close enough. The one I recently did was off like 1/4" +/-. I wish you were the architect for that project. They gave me so many problems with the submittals and kept putting notes about being a smooth, continuous shape with no visiable kinks.

The stair that I'm creating this time around is different where the treads cantilever out off of a center pole and have cut edges that follow an elliptical opening above the stair. The big question is will the architect use a laser to check if I'm exactly lining up with his opening. I surely hope not!

Thanks again for the help.

[sbrown]

Then here is what you do, draft the stair using true ellipses, model using arcs for 3d and section value. In plan just turn the stair off. If you have other stairs then you will need to use worksets or design options to turn it off by itself.

[luigi]

If you have graphic standard, or equivalent book, look at the section that constructs ellipses. In reality an ellipse is nothing but a construction of arcs...yes, sometime a whole bunch or arcs with the center, start, end complicated to find, but nonetheless created by arcs. I am not sure which method ellipses Autocad/Revit, etc. uses...

But, if it is for con docs, then Scott's method is just fine....

[aggockel50321]

Take a look here. (http://www.du.edu/%7Ejcalvert/math/ellipse.htm)

Scroll down to the section called "Ellipses and Drawing". There's a bunch of ways to construct the ellipse, either out of arcs, or loci of points.

At least it'll give you some amunition on what constitutes an ellipse.

[cadkiller]

In Autocad you have the option of creating two different types of ellipses with the Pellipse variable.
This option should also be available for Revit IMO.
Also the ellipse tool should be available for creating stair boundries or at least give the ability to select an ellipse.

Scott's recommendation is a great work around and should do the job for me.

Type: Integer
Saved in: Drawing
Initial value: 0

Controls the ellipse type created with ELLIPSE.


0 Creates a true ellipse object.

1 Creates a polyline representation of an ellipse.

[sbrown]

If you create your ellipse using the polyline feature in acad, then import that and explode it you would get your series of arcs that could then be used for you stair creation in revit. Just make sure you trace over them with the tangent arc line so you don't get all the joint lines.

[cadkiller]

Take a look here. (http://www.du.edu/%7Ejcalvert/math/ellipse.htm)

Scroll down to the section called "Ellipses and Drawing". There's a bunch of ways to construct the ellipse, either out of arcs, or loci of points.

At least it'll give you some amunition on what constitutes an ellipse.
Andrew;

Thanks for the link. I have similar links and am aware that there are many ways to create an ellipse. The same goes for the programs that create them. I wonder which method Revit uses. I had an ellipse on a job that I couldn't duplicate, the ellipse was probably created with Microstation or some other program. I tried several different ways and was forced to recreate with arcs traced over the original. Like I said before it wasn't perfect and had minor differences. That is where it would be good for Revit to allow selecting of these imported ellipses for boundry use. Also like Scott mentioned I could use Autocad; but then I would need two programs to get the job done correctly. I'm trying to make the transition to Revit 100% and not have to have the need for another program.