Handrail - curving staircase

I need to create a handrail (rectangular steel section) for a curving staircase.
I have manually created lines along the edge of the stairway, offset them inwards and raised them to the right hight.
However the sweep1 command does not perform well.

Any ideas for easier modelling of this?

If using Sweep1 then make sure to select the Roadlike option from the dialog box, otherwise the rail will twist. Also, make sure to blend the guide curve between the horizontal and rising sections (can’t see from your image whether you’ve done this) so the rail is comfortable to run your hand along and that will help Sweep1 play nicely.

This shows a handrail created using Sweep1:

If you still have trouble with yours, post the model here so someone can take a look at the actual geometry.


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take one of the curves and use the command slab
edit: hm maybe not.

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Nice alternative @encephalon. Just one thing to bear in mind with Slab: it maintains the same vertical dimension regardless of the angle of incline, so the thickness will vary along the length, whereas Sweep maintains the cross-section perpendicular to the rail. The choice will have implications for fabrication.

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well it does not seem to be an easy task. sweep1 does indeed not produce anything usable in a similar set up. can you post your curves that somebody can use your example to come up with something?
slab actually produces a good result but only if you use continuous curves without kinks, and in your example there are some so this will fail.

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Unfortunately, the blend curve function has to be eyeballed, and therefore hard to control the radius.
If I don’t do the blend curve get a failed joint in the bend. which also won’t trim afterward.

I have attached the file.handrail.3dm (2.2 MB)

I’d put a 100mm radius sphere centred on each sharp corner of your guide curve and use them to trim out the curve sections within their walls:

Then use the adjustable BlendCrv command with curvature continuity to remake the guide without sharp corners:

That will allow Sweep1 to produce a clean surface and will produce a nicer handrail to use (but you could spend some time trying different size spheres to optimise this):


if you are allowed to make smoother transitions then you can rewire that kinky curve. in such messy situations i sometimes use divide, in this case i used 155 and used the resulting points for CurveThroughPt set to Control Point. using slab should then work well.

i did not respect the initial profile just a quick test, but that should work fast and sufficient.

handrail.3dm (2.6 MB)

The way I ended modeling this (cumbersome):

  1. Establish a curve at the right height and offset from the wall. (curve by 3 points)
  2. Offset curve to both side to establish with of handrail
  3. Sweep2 with a straight curve (adding slashes along for a non-deform geometry).
  4. Fillet surface to get a rounded bend where a horizontal section meets an angled section
  5. Offset surface to get the thickness of the handrail.

Would be nice with better Rhino tools to perform these tasks quicker and more efficiently.