19 Replies Latest reply on May 25, 2011 2:25 PM by Brent Zartman

    Smooth Box

    Brent Zartman

      I am fairly new with SolidWorks, but found myself in a situation where I am trying to create a smooth sided rectangular box with C2 curvature everywhere. All the faces are domed, so there are no flat edges, and the edges blend faces smoothly. The concept is very similar to the surfacing challenge: Puffy Box found at http://www.dezignstuff.com/blog/?p=1490 except that all the edges smoothly blend each face. Any suggestions would be greatly appreciated.

        • Re: Smooth Box
          Jeff Mowry

          Can you create a block and then apply fillets (using the curvature-continuous option, instead of tangent option)?  If not, is it really a box, or is it some other form of oblong shape?  (In other words, are there any planar surfaces remaining at all or not?)

          • Re: Smooth Box
            Andrey Dankevich

            Hi Brent,

            You should try to import box tsm models from enclosed archive,

            but in order to do this you need to install tsElements for Solidworks add-in (http://www.tsplines.com/products/solidworks.html). There's 10-day free trial.

            Then do some push-pull manipulation to get the shape you need.

             

            I think the archive I've attached is also included in the add-in download.

             

            Hope this will help you.

             

            Best regards,

            Andrey

            • Re: Smooth Box
              Charles Culp

              Brent,

               

              I've been fairly busy recently, but I finally got a chance to take a stab at this. My model seems to be pretty clean. I used the fillet tool to create curvature continuous face fillets. Then I trimmed the corners and used fill. I had to then pattern to add it to all faces. Is this what you were looking for?

               

              CurvBox1.png

               

              CurvBox2.png

               

              CurvBox3.png

                • Re: Smooth Box
                  Robert Stupplebeen

                  Charles,

                  Since I do not have 2011 can you post an image of your feature tree?  Thanks.

                  Rob Stupplebeen

                  PuffyCube2-RStupplebeen.jpg

                    • Re: Smooth Box
                      Charles Culp

                      Rob,

                       

                      The important step is to click the "don't trim and attach" for the fillets, apply to all face intersections, then hand trim afterwards. Then trim the corners, and fill. Here is a screenshot from each major step. I made the box a little more "curvy" to emphasize the curv. continuous aspects of it:

                       

                      First, make a puffy box. I like to define each face. In this example, I sketched on the top plane, but I could not just sketch on the right plane (I'm not sure why, but it didn't think the sketches interseted). So I created a reference extrude, then I rotated it. Then I created a 3D sketch, selected the edges, and converted them into sketch elements again. Now it works, for whatever reason.

                      CurvyBoxStep1.png

                       

                      Then fillet each corner using face fillet, with the curvature continuous option checked. Also, select the option for "don't trim and attach". This allows you to fillet all edges equally. You can then use the mutual trim tool to trim away all the free edges (orginal box shown in transparent gold). Note that you don't actually need all these fillets, just 5. This is an artifact from an earlier attempt. Why 5? Because I'm just going to pattern one fillet, face, and corner later. The 5 is nessisary because I need the 3 on each side of the filled corner. I also need two adjacent sides, to have a trim plane for Plane 4 (see the step 2 down).

                      CurvyBoxStep2.png

                      Because the surfaces intersect at curvature continuous, just trimming the face isn't defined very well, and the trim looks awkward (read: wrong). So I use a 3D sketch with converted entities on the edge, and then use that to trim away each large face. Well, just one large face, which I will then pattern later.

                      CurvyBoxStep2.5.png

                       

                      Use Plane 4 to trim one side, then Planes 1, 2, and 3 to trim away the corner. I tried to just trim the original corner, instead of offsetting each face first, but then you run into a small problem of the corners of a single body touching, but not forming an edge. This is the surfacing equivalent of "zero thickness geometry". You can get around it by using "replace face" instead of forming a seperate fill body and then knitting. The problem with this method is you cannot pattern a replace face, so it was just easier to do it with the method below.

                      CurvyBoxStep3.png

                       

                      Now you just use those trimmed surfaces to make a fill with curvy continuous edges.

                      CurvyBoxStep4.png

                       

                      The final step is to just get creative with circular body patterns, and then knit the result. There were some gaps above the default tolerance, but the end result looks good.

                      CurvyBoxStep5.png

                    • Re: Smooth Box
                      Brent Zartman

                      Charles,

                       

                      Thank you very much. I am not too excited about using fillets on a smooth model. However, your model approach does provide an elegant solution. Since the front and back of the model I am creating are different from  each other, I will have to modify your method a little to get what I  need on this project. The one thing I do notice on your puffy cube is that the transitions to the edge radii seem a little. Is there a way to control how the C2 fillets work so that the transitions are more gradual?

                       

                      Again, thanks

                       

                      Brent

                        • Re: Smooth Box
                          Charles Culp

                          Brent,

                           

                          Using the face fillet tool with "curvature continuous" will create fully C2 blends, as you can see from my model. You cannot control the strength of the transition, however. The only options you really get are the nominal size, and the option to make it constant width.

                           

                          If you want to increase the strength of the corner, the only way to do that is by creating a boundary surface by hand. This isn't as hard as it may seem, as you can use the fillet tool first to create your trim boundaries. What I mean, is that if you look at my second image above (the one with the semi-transparent gold cube), you can just use the edges of the blue transitions as your starting and end edges for the boundary surface. Then in the boundary surface tool you can alter the strength of the tangency (after making it curvature continuous, of course). I will post that example too, if I get a chance.

                      • Re: Smooth Box
                        Matt Lombard

                        http://www.dezignstuff.com/images/triangle2.png

                        Here's a 3 sided one I did for another blog post http://www.dezignstuff.com/blog/?p=779

                         

                        It's not as easy as it seems. Different methods to do it shown on the blog.

                         

                        I did one as a paid project to make a block with sharp corner points, but bulgy sides. That was probably even more difficult to get it right.