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Multi-Segment Swept Blend with Height Increasing Uniformly

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    Multi-Segment Swept Blend with Height Increasing Uniformly

    Hi All,

    (If the following is too long to read, basically all I am asking is what would be the ideal way to create the geometry with a red arrow pointing to it as shown in the attached image: 3D View, without any messy lines where geometry doesn't join AND preferably without the use of adaptive components).

    I have (through a very elongated and not quite perfect process) managed to create the multi-segment swept blend form shown in the attached image (3D VIEW) and .rfa file (SCREEN.rfa).

    The wall or screen shown starts at a height of 300mm and uniformly increases in height until it reaches 2100mm at the end of the path.

    I had initially tried to use a spline as the path for my swept blend (this is the darker geometry seen in the plan, front elevation, 3D view and SCREEN.rfa file), however this resulted it the top edge of the form being disjointed and uneven, as can be observed in the attached images.

    I next tried to create an Adaptive Component family that could create this form (see image: Adaptive Component Family). This is not ideal because this screen element will form part of a joinery unit I am trying to model, and it is not possible to load an Adaptive Component family into a Generic Model family - meaning I can't have the joinery unit and the screen packaged in the same family. Despite that I thought I would try. I loaded the generic model family containing the rest of the joinery unit and the adaptive component family into a project and used reference lines embedded within the generic model to trace the path in plan however the resulting form did not follow the path I had drawn accurately and was irregular when viewed in plan.... Back to the drawing board :banghead:.

    Finally, I decided to try an overly complicated method. I noted the individual length of each of the 7 segments (lines and arcs) that made up the total pa. For each segment I calculated it's % of the total path distance. I then used those %'s to determine the change in height required from the start profile to the end profile for each segment, in order to achieve a uniform increase in height. Finally I created 7 individual swept blends, each with rectangular profiles of differing height, resulting in the lighter from shown in the attached images.

    This gave me an almost perfect result, however I couldn't get all the individual swept blends to join to create one joint shape. The first 2 and the last 5 segments joined, however I can't get segment 2 to join segment 3. (The arrow in the image, 3D View, shows the line where I can't achieve a join... I have attached the file screen.rfa for reference. If anyone can solve this I'd be greatly appreciative.

    Despite (almost) achieving what I was after, there has to be a much simpler solution to create a Multi-Segment Swept Blend with uniformly increasing height, and within the normal family environment.

    If anybody has any suggestions on a more user-friendly approach to creating the required geometry I'd love to know!

    Thanks for your time.


    Attached Files

    Why not make a simple extrusion and then use void to cut it the way you want?


      How would you do that? You can't just create an angled void from the shortest point to the highest point and extrude through the solid form. The geometry doesn't allow for that. It's not that easy unfortunately.
      Last edited by denden; February 17, 2017, 10:53 AM.


        Maybe I didn't get it right what are you trying to accomplish, I though of this solution


          No sorry that's not what I'm trying to achieve. That method won't produce the geometry I'm after.


            Unfortunately, you'll find that unless you're perfectly tangential in your intersections that you will not clean up the top surface of your swept blends.

            I don't think it's possible in the software to get tangent to a sloped swept blend. I believe your best bet is to use a spline and use a void to clean up any issues at the end.
            Developer at Anguleris BIMsmith Marketplace.
            Previously at Sumex Design for


              I personally would have focused on making a Plane that accurately represents the top condition of the walls. Then put a Generic Roof on it, and use Attach To Roof. Its not awesome to have an extra roof in the model that you dont need, but you can move it to a phase later than the project itself, and youll only see it when you need to edit it.
              Aaron "selfish AND petulant" Maller |P A R A L L A X T E A M | Practice Technology Implementation
              @Web | @Twitter | @LinkedIn | @Email


                Originally posted by Andrew K View Post
                Unfortunately, you'll find that unless you're perfectly tangential in your intersections that you will not clean up the top surface of your swept blends.
                Im not too bothered by the lines on the top surface. It's just the join line shown in the attached 3D view (red arrow pointing to it) which bothers me. I have no idea why I can't get those two segments to join? I even tried extending the swept blend path to ensure the two swept blends intersected but no luck. Any thoughts on why they're not joining?

                Thanks for for your informative reply.


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