# Spiral around freehand pipe + paper strip unroll

Hello! I want to draw a spiral around any kind of freehand drawn pipe and then use a paper strip method to undroll the result into 2D. It is very easy to do when the segments are straight. But I fail to do it with anything an idea more complex.

Don´t mind the example geometry, could be more or less any other curved path.

Pipe.gh (2.0 KB)

P.S.: I was able to create a spiral using @laurent_delrieu tool. Now I only need to generate a surface or a mesh which can be unrolled into 2D strip.

Pipe_2.gh (9.6 KB)

Hello
If mesh is acceptable I will say.
Make the curve around the shape turning with a certain direction.

Point1 = Curve.Start
Point3 = Point touching or the edge or the curve when going from point 1 at a direction at 90° (left or right depending on curve twist orientation) from the curve direction.

While (point1 not near curve.End)
Point2 = Point at a certain distance of point 1
Point4 same way as Point3 but going from Point2
Make a face (point1, point2, point3),
Make a face (point2, point4, point3),
Point1 = Point2
Point3 = Point3
Continue

OutPutMesh could easily be unrolled as it has no inner points.

It works quite, still some tuning. it uses my geodesic path script (the one you know) on mesh as there is no or not visible geodesic in Rhinocommon except ShortPath.

Tube
Area = 1575105.5 (+/- 0.47) square millimeters
Strip 3d
Area = 1504600.25 (+/- 0.001) square millimeters
Strip flattened
Area = 1504677.21 (+/- 0.001) square millimeters

Ends still missing
brep strip.3dm (548.7 KB)

2 Likes

This is more or less what I was doing the whole day manually! My friend… once again you manage to blow my little mind away Outstanding!

I did the meshing in grasshopper, but then did the unrolling in SketchUp using the Unwrap and Flatten plugin, because it allowed me exactly this type of directional unrolling, only manually and very fast.

The only difference is that I used triangulated mesh, but it should have been obvious to me that quads would work just as well.

Hello David,
I used my geodesic path generator to do that. I also make a triangular mesh. But for some reason it is not good at the moment. So I used a loft to generate the strip.
I will send you the script when more usable and complete.

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I think, and this is just a guess, that the reason why the loft works and the mesh doesn’t is because the loft keeps the order of the faces, and the mesh is mostly random in that regard. Not sure, I will check this a bit later today.

I have tried the geodesic script, but also your spiral script from an old thread. It is in the files above. It also does a very nice job.

Now my mesh is working!
Output as Mesh or as Brep.

2 Likes

Looks stunning as usual !
Is any of this related to this paper from Leduc et al, 2018, An innovative fabrication process from rolled helicoidal steel strips ?

Another question I have : a geodesic path is supposed to be the shortest curve between two points, and a spiral around a shape is definitely not the shortest path between its end points, so what do you call a geodesic path in this context ?

I didn’t read the paper but thanks for linking it. I did that with what I know. But I have other ideas because this can be useful for others things.
I use the geodesic “walker” to go perpendicular to the first curve (a spiral here).
I could have used other type of curve to go perpendicular, a line could surely have done the trick. I will perhaps also try this.

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One script that doesn’t use Geodesic path and that is able to do multi strip.
Some time it is mandatory to play with tolerance or others parameters but seems to works. Also for closed curves, but strips are not closed.
Not fully functional but it could be useful for someone that has some use of this kind of strips

BREP stripping spiral LEGACY.gh (31.9 KB)

4 Likes

This is clever, I can build these mixing different materials now I have even more funny ideas now!

Wow, if you are actually making these please post a photo in the gallery or here!

Hi there, I can’t seem to find this geodesic script that you have mentioned in this forum thread. Is it possible to link it to your previous posts? Or do you still have the grasshopper code for this particular mesh? If so could you link it here? It would be a great help. Thank you!

Hello
This geodesic script is not published openly. You 'll have to find one another or code it by yourself. I quite no more publish tool.

Look at lion fish plugin
https://www.food4rhino.com/en/app/lion-fish

Normally i have the same project but it is a bit complicated. is there anyone who has an idea?