Sweep 1 error


#1

Hi community,

I am getting an error when trying to sweep 3 polygons with a rail. It is for the spine of chaise lounge and gets blown out of proportion around the steeper bend. I have tried to split the job into two sections to no avail. Here is my 3dm file. Hopefully someone can shine light on this as I’m stumped and it has always been simple in the past. It is suppose to start with a smaller area polygon, then increase before retreating back to the original or close to the original area. There is an example of a similar finished one next to it that is not right but close.

Thanks in advance. sweep 1 issue 2.3dm (1.0 MB)


#2

You will need to add a couple more cross-sections or maybe do it as a Sweep2(or some totally different way) to stop it from folding over on itself going around that bend. Your cross-section is taller than the radius of the blend, so it’s going to fold over without something more to control it. You also have a discontinuity in your rail curve closer to the front that’s causing a break in the shape.


#3

Thanks for the reply Jim. I initially had about 25 cross sections and had the same issue. Next I traced the revit model and did sweep 2. I got the result, but it wasn’t as easy as I thought it should have been. I am aware that the center cross-section is taller which is how it is supposed to be. I am thinking about breaking it into two sections and merging the shapes. Do you know if theres a solution via grasshopper?
Thanks again


#4

Well 25 sections are too many but 3 are not enough. There are certainly other ways of looking at this, it’s not “really” a single swept shape, it’s two swept shapes that blended together at that troublesome corner, so maybe you should look at it more like that. Myself I’d probably try to ‘decouple’ things by working on the side profile outline of the shape totally separately from the side surfaces, which I would then trim off.


#5

Here’s one approach, the shape is pretty simplified but you hopefully get the idea. I drew curves for the top and bottom side profile, then simply lofted them together and did some point-editing to get the tapered cross-section, mirror and loft between the edges. sweep 1 issue 2 (1).3dm (1.1 MB)


#6

Yes that works for sure. That is similar to the approach I did, but had to loft the side profile in two sections as it went haywire at the troublesome curve. You’re approach is definitely the best method. I will do that. Thanks Jim!