3D spiral- how to make?

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Bill

That's no fun!

One way to draw a 3D spiral with out a program is to use spline or the

3dpline and polar coordinate point entry ( distance < angle, Z)

To make this easy you would do this off a User defined UCS origin distance being the radius of the spiral angle being the angle of incrimination about a circle. Z being the rise per angular step.

for a simple example a spiral a 6 unit rad and 6 segments about a circle and a 1 1/2 unit rise per rotation would enter as

spline

6,0,0 ( start point) 6

And if that looks too much like hard work use Excel to calculate each point and save the results as a script file.

Terry

message

Terry is correct. I have Some cad training using a book by John E. Wilson and the book says the same thing.

I'm using AutoCAD 2002 in witch command 3Dpline does not exist, and like You said, neither extrude nor tabsurf works with spline. So it looks like the only way is lots of UCSistems, many arcs and extrusions. Unless You have any other idea.

"3dpoly"

Yes, but I can't force it to go through the points when spline curve is used (in pedit).

Sorry, just meant to say the command is "3dpoly" and not "3dpline", whether or not it works for your application. I just found a link that may or may not help you, but will give it to you anyway because I think it does the best job describing how to model something that is fundamentally a 3d spiral. It is an in-depth tutorial on modeling a 3d screw, but perhaps you can apply the concepts to your stairway.

Good luck, LT