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Ziska

curved stair support-and final vs artistic

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Okay- there are a "bunch" of issues with this...

Stair on a volute- which needs the two square tube supports drawn:

Image 1 shows the rise- and where the support needs to hit each tread- it's in

artistic render mode.

Image 2 shows the support in artistic render mode- unfortunately this is 4 nurbs surfaces -created from polylines in plan and then reshaped as a 3D poly in elevation then "renurbed"- to get this as a single object would be nice (haven't a clue- tried loft, 3D poly's , add solids, fillet, I'm stymied- all suggestions welcome)

Image 3 shows the same as image 2 in final renderworks mode- a fairly unimpressive sight....

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Lamberto,

I wish it were that simple- this was taken from the Designers free hand sketch- mulitple centerpoints and multiple curves- the only constant is an 8" rise for each tread.

http://www.ziskachilds.com/images/drafting/people41201.gif

I've made a compromise by using short straight bars under each step

http://www.ziskachilds.com/images/sketches/stair-v11.jpg

I will try and post better pictures soon...

Grazie,

Ziska

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I think that better pictures are required for a better analisys of the project.

people41201.gif to demostrate a complex stair structur.

Multiple centerpoints are for rise surfaces.

From your gif there is possible to see two circle from top view with different center points.

8" rise for each tread isn't too much for stair?

Ciao Lamberto

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Lamberto,

8" is for camera- no one ever walks up the stair- think of it as sculpture more than a "stair"

A sweep would work if the rise were constant- which it is not.

Yes, better quality pictures are needed- won't get to that until Monday.

Thanks,

Ziska

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Hello Ziska:

You could make this staircase by drawing a polyline of the top view the two offset arcs for the innner and outer curves. Then cut the polyline with lines at the locations specified in the drawing to make tread polylines. Extrude each one 8" thick and move its z to the correct height for that tread.

For the supporting stringers(?) under the treads, try out the Model->Create Helix-Spiral command, using a selected vertical line as the helix axis. The start and end radii of the helix should be the same as the radius where each support beam is located. You can then use the helix as a path for Extrude Along Path, with a rectangle as the profile to be extruded.

Or, you could use Sweep on a rectangle with a 2D locus at the axis location with a pitch to make a helix shape. (The pitch dimension is relative to a full turn of 360 degrees.)

Hope this gets you closer to the required model,

[ 09-10-2004, 02:44 PM: Message edited by: Dave Donley ]

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An other way, a bit more complicated, for supporting stringers under treads or for rail is....

Create a Nurs curves that they represent the supporting vertical section for each tread ad then use loft command to create a nurbs loft surface or....

after Nurbs curves are created and correctly positionated you can group it and start this little script. It's a little time saving.

Ciao Lamberto

{copy from this line to .....}

Procedure CreateLoftSurfFromGroup;

Var

HNurbsSurf:Handle;

Begin

HNurbsSurf:=CreateLoftSurfaces(LSActLayer,False,True,True);

End;

Run(CreateLoftSurfFromGroup);

{....this last}

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Dave,

The treads are easy- connecting them with a smooth curving piece of metal is not. Since the rise for the first 4 steps is much less than the rest of the stair a sweep with begin and end points on the top and bottom stair cut through the treads. (wider treads = more shallow rise over distance) I could certainly create individual sweeps for each section under each tread -or- what I did for the 3D- straight rectangular bar stock connecting from bottom of tread edge to bottom of tread edge.

Having created a polyline which follows the shape (with all it's varying pitches) I had hoped that I would be able to loft two surfaces together- which resulted in the rather disturbing "final render" above. (Still no idea why the artistic render differs so greatly from the final render)

Lamberto's script is the next thing to try....will report back soon....

Many thanks to you both!

Ziska

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How about this? Place 3D loci (in plan view) at each intersection between the support and the stair treads (this does assume similar size "notches" on each tread) and then move them in the Z direction for each step. You can then use the nurbs tool to connect these "3D dots" and form the basis for skinning a nurbs surface and thickening it up with the shell tool. You can then do some 3D subtractions as necessary.

[ 09-15-2004, 07:46 PM: Message edited by: tom kyler ]

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