topic Re: Sweeping a stringer around a curved stair - Help in AutoCAD Forum

Sweeping a stringer around a curved stair - Help

adamdio — Thu, 22 Aug 2024 08:26:40 GMT

Is there a way of creating a section of curved stringer to follow my tread line on the inside? I start with a flat stringer and will end with a flat stringer - Can i create a curved stringer that will join to those 2 flat bar stringers?

I will attach an image and i hope it makes sense. To explain a little more, the curved section i have drawn is exactly where i want my curved section of stringer to stop and start, i just don't know how to follow the line of my treads to 'cut out' a section of stair stringer from this.

Re: Sweeping a stringer around a curved stair - Help

parkr4st — Thu, 22 Aug 2024 10:10:17 GMT

Please post with the .dwg file attached. the stringer should follow the line of a helix. with the .dwg it can be tried by others.

Re: Sweeping a stringer around a curved stair - Help

adamdio — Thu, 22 Aug 2024 10:14:06 GMT

Thank you - Attached to this comment.

Re: Sweeping a stringer around a curved stair - Help

leeminardi — Thu, 22 Aug 2024 18:21:27 GMT

You can sweep a rectangle either along a helix or spline.

I did a rough test and tried the helix route and from the top view determined that the angle subtended by te curve is 62.21°.

It appears that the curve starts at the outside corner of a tread and ends at a midpoint. It would be better it the curve started and ended at the same point of a trend.

62.21 / 360 = 0.1728, the number of turns for the helix. I got a vertical z from start to end of 1307 (1200 for 5 steps plus half a riser) for the helix heght.

With this information, and the curvature center point, you can create a helix. I then swept a rectangle along the helix yielding:

Obviously some tuning of the helix paramters are needed.

Re: Sweeping a stringer around a curved stair - Help

adamdio — Fri, 23 Aug 2024 09:05:43 GMT

That is perfect and worked up until I tried sweeping around my rectangle stringer - I cannot get it to follow the line of the curve I have created, it always tends to veer off.

Re: Sweeping a stringer around a curved stair - Help

leeminardi — Fri, 23 Aug 2024 10:55:40 GMT

Post a copy of the drawing with your results. Be sure to include a copy of the helix and rectangle you used.

Re: Sweeping a stringer around a curved stair - Help

Washingtonn — Fri, 23 Aug 2024 13:23:45 GMT

I have used this method for curved and sloping storefronts.

(view in My Videos)

Re: Sweeping a stringer around a curved stair - Help

leeminardi — Fri, 23 Aug 2024 14:44:12 GMT

@Washingtonn Great documentation! Nice work

There are slope discontinuities where the curves meet the straight sections particularly noticeable at the inside lower seam. Resolving this may be complicated by inconsistencies in the original tread model.

Re: Sweeping a stringer around a curved stair - Help

Washingtonn — Fri, 23 Aug 2024 15:15:01 GMT

Thank you.
Yes, the original model has a number of issues which should be resolved prior to generating an accurate model for fabrication as you are aware.

Re: Sweeping a stringer around a curved stair - Help

R_Tweed — Fri, 23 Aug 2024 16:58:13 GMT

Have you considered using loft with a path?