This info is exactly what I've been looking for. Just checked back in and haven't had a chance to go through the posts in detail. Jeff, thanks so much----quickly scanning I can see there's much to check out.

What I've been doing is to confirm overall fit and lay-out in 3D with SU, but detailed templates and shop drawings get done in conventional 2D dwg's.

I've seen Rhino mentioned here, but did not understand that it might have something to offer. There's is a bit of resistance (mine) to learning a new bloody program!!

I'll be checking back in later----gotta go build something.

Dale,
re. the springback calculator----- glad to hear it has worked for you, but we've found it's not infallible.

Just checking in quickly.

Dale, I had wondered if scaling up would help out with the Tools On Surface. The specific element I was attempting to draw was a flare in the stringer at the bottom. ---quite small compared to the rest of the stair. ----and exactly the sort of thing that needs to be worked out for the design approval of a client.
I haven't opened Jeff's file since I'm still using SU 7.0 Pro. Is yours in 8.0? I'm reluctant to upgrade because my video card is about about maxed. It looks like you've have good results also. I may see if they have a viewer.
This dialogue has been--and continues to be very helpful. Jeff mentioned he had some additional thoughts on drawing strategy. I'm looking forward them.

Thanks for the spreadsheet link (and your compliments on our work)--- I'll definitely check it out.

I'll check in later
Dan B.

Jeff,

Excellent! The element that I've had trouble with is the stringer ---ie. the side of the stair below the inside radius tread ends. I need to upgrade my SU to v.8 in order examine your model more closely. I'll do that later this today.

and another view from the side

Actually the pitch may change because there is a transition from straight treads to winders, which shortens the run of the tread relative to the rise (which does stay constant).
And some stairs are nominally "elliptical" in that while their plan may not be described as a true ellipse, one portion will have a broad radius and other sections will have a tight radius.
Jeff, there are many "elliptical" plan stairs in those old Manhattan and Brooklyn brownstones in your area.
The stringer of the stair shown in the accompanying photos varies in pitch and plan radius. The upper treads are straight and have three baluster. The lower treads are two baluster per--, and the lower end at handrail volute tightens into shorter radius. Yes the upper portion of the stringer is straight in plan, but a smooth transition was made into the steeper curved section. The second photo illustrates the sort of curve that might be developed on a cylindric surface.

Dale,
Sorry, but your example doesn't work really. the stringer generated is narrow in the middle and wide (taller) at the top and and ---well, there are a bunch of other issues.

I actually use the geometry of cylindric sections often in my work, but re. SU and what I'm trying to accomplish with it,---that's not the answer.

Simple helix is not a problem. The issue is creating transitions between helixes of different pitches.

Think of a handrail on a circular stair that does a graceful transition either to level or to a section of the stair that is not pitched the same. The top of the stringer below is usually similarly configured.

Most stair models I've seen here are simple spirals. While portions of some of our circular stairs can be developed as simple spirals, most are more complex and have been very difficult to draw in SU
Attached is a photo/example of one such of transition.

Then again ---got shape to work once -----then no deal.

compared to the complexity of follow or extraude along path this should be pretty basic.

It is the application of wrapping a 2D spline or arc curve to a cylinder. That gives me a reliable work path.

I'd finally hoped i'd gotten to a reliable method of creating 3D's of this stuff.

Pretty frustrating.

Jeff,

The shape bender looks like it may be very useful. ie. the best route. I have the Fredoscale, but haven't found the key to making that tool give me desired results.