Stair Stringer Modeling help

[Geoffc]

Being an architect, I usually get away with modeling in Autocad.

 

But I'm trying to model a steel stair stringer, C-channel shape along a path, and the stair has curved ends, so I can't use a 3dpoly in Autocad.

For a work-around, I've created some of the segments as 2d poly's in Acad, then imported them into Max, and raised the segments from there in the Z coordinate.

 

A couple questions:

With a spline segment, it is possible to raise the end of the segment in the Z direction, and have all of the segments follow it naturally? As opposed to manually raising each mid-vertex to the correct Z coordinate? Imagine if you were to take a metal wire in a 2d shape, and as you pulled up on one end how the entire wire would bend up like a spring. (I'll see if I can post a pic).

[Geoffc]

Also, and I apologize if this is basic stuff, my loft in Max flips itself from the spline. For this example I raised the vertexes of the spline manually in the Z direction, the C-Channel shape was brought in from Autocad, and then lofted using the spline. I've tried most of the variables under the loft properties, but can't figure out why it flips the shape from the spline.

 

Spline

 

Loft

 

Loft Properties

[BobM]

Try selcting the path first then get shape.

 

 

 

I have just tried it with imported path then shape and it works OK

 

Hope this helps

[Geoffc]

Bob, thanks so much. So simple yet I would have never guessed that.

 

Any idea on my first question too? How to import a multiple segment poly, then raise (stretch) the entire segment up by just grabbing one of the end vertexes?

[Kawzy]

Well, the easiest way to move vertices at the same time is to use soft selection. When you're in vertex selection mode, select the vetex you want to be at the highest point, then activate the soft selection rollout, check use soft selection, and when selecting linear vertices, make sure to also have "edge distance" checked. The number to the right is the maximum number of vertices you'd like to effect. By then adjusting the falloff value, you basically create the percentage that each vertex is effected, red being 100% and dark blue being close to 0%.

 

And to also answer your second question in another way, if you hold Ctrl while selecting the shape, it'll flip it as well.

Edited February 12, 2010 by Kawzy

[Geoffc]

Thanks Josh. That's a little tricky with the soft selection, but I can definitely see the logic of how it functions. I'll give it a spin.

 

 

....and someday I really will revisit my spline and mesh modeling tutorials.

[Peter M. Gruhn]

I'm wondering if that wasn't something you couldn't extrude on a path in AutoCAD.

[Geoffc]

After I moved the spline vertexes in the z direction the first time, I went and reimported it back into autocad and used the sweep command, but it rotates the shape as it passes through the curves. Max has the ability to shut that off and keep the shape vertical. Unless of course I'm missing something in Autocad that would have prevented that.

[Peter M. Gruhn]

Ah... I see. Thanks.

 

I have no idea if ACAD can fix that.

[jsf]

Try using the Sweep Command, it allows you the ability to reposition the Profile while keeping your path spline stationary. The profile can also be offset and mirrored.

[Geoffc]

Back again, still playing with trying to draw a 3d arc. We realized that sketchup can do this, if we know the start, end, and a middle point of an arc (importing these points with the correct Z coordinates from autocad.

 

Ok, why can't I do this in Max? Problem with sketchup is moving the resultant 3d arc back into max or autocad results in a segmented polyline, not an arc.

 

Again, I never draw with splines, but I'm trying the same method in Max: "End-end-middle", using these 3 points with z-coords. It keeps drawing a 2d 'flattened' arc. Am I missing something basic?

 

Thanks again!