Sweep a Spiral Stair Channel Shape Along Spline

[Bill Tillman]

I am once again trying to get the hang of drawing a 3D spiral staircase and cannot seem to figure out the SWEEP command properly. I have a channel, or a rectangular tube shape which I want to use for the stringers. If I use a round tube, like when I do the handrail, there is no trouble. But when I use a channel or rectangular tube shape the SWEEP command causes the shape to bank and I end up with an unuseable shape.

 

In the attached drawing (ACAD-2007 format) I have shown a SPLINE which indicates the path I want the outside stringer to follow.

Spiral Stair(02).dwg

[Jack_O'neill]

Is this closer to what you wanted it to do?

u.dwg

[SEANT]

This is another method.

Copy

Loft

Thicken

OffsetFace

Stringer.dwg

[Jack_O'neill]

Guess I could have said how I did that...stayed up too late last night, and not enough caffiene this morning yet.

 

Seant's way may be closer to what you wanted, Bill. I took your rectangle, copied it to the top and swept it down the path with a 45° twist angle.

[kencaz]

This is another method.

Copy

Loft

Thicken

OffsetFace

 

Can you give a little more detail on your procedures SEANT...

 

Thanks

 

KC

[Bill Tillman]

Can you give a little more detail on your procedures SEANT...

 

Thanks

 

KC

 

Yes, what kencaz said...that looks pretty cool. I think I figured out a method on my own, although it's a tedious process of copying a section of the channel at each nosing location and then use LOFT to extrude the shape. I still have some fine tuning to do with this but at least it get's me in the ballpark.

Edited July 3, 2011 by Bill Tillman

[SEANT]

Sorry, I was pressed for time and left a rather vague description.

 

 

I copied the helix spline 10” down to the bottom of the rectangular profile. I lofted the two Helix/Splines, accepting the “Cross Sections Only” option. That created a surface entity (I left a copy of that surface in the dwg file – see at the middle of the solid).

 

 

The Rectangular profile was 2” wide, but because of the orientation of the surface at the middle, I thickened 1”, and SolidEdit-OffsetFace the other inch.

 

Cool stairs, by the way.

[Jack_O'neill]

Groovy looking stairs Bill. I'll be building stairs tomorrow myself, only these will be out of wood instead of pixels!

[kencaz]

Sorry, I was pressed for time and left a rather vague description.

 

 

I copied the helix spline 10” down to the bottom of the rectangular profile. I lofted the two Helix/Splines, accepting the “Cross Sections Only” option. That created a surface entity (I left a copy of that surface in the dwg file – see at the middle of the solid).

 

 

The Rectangular profile was 2” wide, but because of the orientation of the surface at the middle, I thickened 1”, and SolidEdit-OffsetFace the other inch.

 

Cool stairs, by the way.

 

Thanks SEANT,

 

That seems like a better method then lofting profiles...

 

KC

[Bill Tillman]

Groovy looking stairs Bill. I'll be building stairs tomorrow myself' date=' only these will be out of wood instead of pixels![/quote']

 

Yes, very ornamental. I doubt I can get anyone to pay for the waterjet or plasma cutting that would be required for this style. Nor do I know of anyone who could roll the channels into those shapes for me. But i know this can be done. I saw a set of stairs similar to this a long time ago so someone figured out how to fabricate it.

[Jack_O'neill]

Yes, very ornamental. I doubt I can get anyone to pay for the waterjet or plasma cutting that would be required for this style. Nor do I know of anyone who could roll the channels into those shapes for me. But i know this can be done. I saw a set of stairs similar to this a long time ago so someone figured out how to fabricate it.

 

Rolling the channels might be a challenge, but you might be suprised on the plasma cutting. They've got the prices down on those little portable cnc plasma cutters down now till they are almost affordable to the garage operator. They start just under $3000....one job might pay for the machine if you got somebody that knows or can learn how to run one.

[Denimoth]

You could always have the stair spiral around a central column or round steel tube/pipe. It would eliminate the need for the twisted inner stringer and provide something for people to hold onto while going up or down, in addition to any railing you would have on the outside stringer.