9 Replies Latest reply on Nov 11, 2013 10:14 AM by Eric Irwin

    Surfacing fails thicken / poor curvature

    Alan Boyd

      Hi All,


      I am attemtping to create a solid model of the following part which is to be open ended on planes 1 and 3, and have a thin wall thickness.


      As you can see I have created a lofted surface between the two profiles on planes 1 and 2, and used guide curves to successfully make the first section, but i am struggling to surface the other end where it blends into the other profiles.  I have sketched roughly using the 3D sketches where the surfaces are to run.


      I have tried lofting a section of the bottom of the lofted profile (one half to then be mirrored and knitted) to a section of the lower surface plane using the first 3D sketch as a guide curve, and lofting the top section of the lofted profile to plane 3, but getting a boundary or filled surface to fill in the gap this creates is where I am struggling as it has poor curvature continuity into the other faces and fails the thicken command. 


      Can anyone help me finish this in a way that can be thickened please?

        • Re: Surfacing fails thicken / poor curvature
          Jesse Robbers

          I can't open the file, future version, work is on 2010 version. My attack for this would be;


          1; Use the Plane 2 sketch profile (kind of looks like a slice of bread) but use the selection manager and do not choose the line at the bottom of this sketch, or delete this line or change it to construction geometry. Create a plane normal to plane 2 at the point where the side view guide curve point at the bottom is located. On this new plane, make a new profile sketch (same as the Plane 2 sketch but scaled down and has relations to your guide curves). Then loft between these 2 profiles and use your guide curves.


          2; Loft between the new plate and Plane 3 the upper part of the profiles (the crust of the bread) and use your guide curves and use tangency or curvature to face for start/end conditions. You may beed to not select the sketch (hide them) and select the edges of the surfaces to allow the tangency/curvature to face conditions.


          3; Then another loft using the bottom planer surface, guide curves, and long nexk type surface edges.


          4; Then you should have a small opening near the new plane that you could use boundary or fill surface to fill it with....or maybe sort out a new loft there. Without being able to work with the file, I'm not sure if you could loft up to or past this small opening area and them trim away the excess using your guide curve profile to give a more tidy transition in this area with more control of it.


          5; Knit, Thicken.


          For symetrical parts, it's less work, faster rebuilds, less things to go wrong or to fix errors if you just work with one half of the item then mirror the body when you get it finished as a solid body or as a surface body ready to be thickened.

          • Re: Surfacing fails thicken / poor curvature
            John Burrill

            Hi Alan, welcome to the forums.

            so what you're getting into is a little bit of advanced surfface modeling-which is different from your conventional modeling because instead of thinking in terms of features you approach this in terms of faces.  In a nutshet, you want to make a quilt of simple faces instead of a one or two big features

            I've messed around with your file a little bit and uploaded the result.


            Note that I didn't have time to address all fo the continuity issues, but it should give you an idea of of how to approach this kind of problem.

            Hope it helps

            • Re: Surfacing fails thicken / poor curvature
              Mark Kaiser

              Here's my novice attempt at it.  There's a feature in mine that fails on control q, with verification on rebuild turned on.  Not my normal work, thanks for the challenge.

              • Re: Surfacing fails thicken / poor curvature
                Eric Irwin

                I don't think I have any failures, but by no means is this truly done.  My first bit of advice is to pay a lot more attention to your curve quality.  Another bit of advice is to try and do larger more consistent shapes and then work on the smaller bits.  You don't seem to have much of the model truly tied down with any dimensions or constraints in your sketches, that can be an issue too.  I got a 3mm thick wall, but I didn't try to go any higher than that.


                • Re: Surfacing fails thicken / poor curvature
                  Alan Boyd

                  First of all thank you for all the responses!  I am very grateful for the time you all spent helping me out


                  I have taken the guidance and completed the model successfully!  I think the critical bit I was missing was the ability to put constraint curves on surface fills, creating one fill with the appropriate geometry, wheras I had tried to do this in two surfaces and was striggling with the join continuity at the constraint curve.


                  Again many thanks all of you!

                  • Re: Surfacing fails thicken / poor curvature
                    Alan Boyd

                    John - I do however have a quick question I hope you can help with!


                    In your build, you lofted Surface Loft 2 from an open group selection (image 01) but when I tried to select the same open droup, it always selected a larger spline length (image 02).  How did you narrow the open group to within the guide curve without having to draw another sketch?




                    image 01.pngimage 02.png

                      • Re: Surfacing fails thicken / poor curvature
                        John Burrill

                        Hi Alan, if you use the group selection tool like you did you can drag the handles on the endpoints of the curve selection to reshape it.  I used this technique for speed, but for a more robust solution that can absorb changes better, you should generate your lofts with 'merge tangent surfaces' turned off and build your loft profiles with split points that have a pierce relatinos to the guide curves.

                        In the case of this part, I think I would have made the top of the piece  a single loft feature so that I didn't have to mess with continuity.

                        Also, you should note the lofts are biased in the direction of the section normals, so  you don't get good tangency control along the guide curves.  You should take some time to familiarize youreself with the boundary surface and fill surfaces for situations where you need this kind of contorl.

                          • Re: Surfacing fails thicken / poor curvature
                            Alan Boyd

                            Firstly thank you so much for all your help on my project.  I am really enjoying surfacing!


                            I have however hit an issue on updating the profile of the main body loft, adding another feature to the wall but therafter making the filled surface fail to match curvature again and therefore have the original issue of failing to thicken...


                            I have attached the updated file and would really appreciate some more help!



                              • Re: Surfacing fails thicken / poor curvature
                                Eric Irwin

                                Your initial Loft has an issue.  You need to move the Cyan dots so that they make sense and line up, there is a wrinkle in that feature of the model you posted.  It should look something like this:



                                The next issue you have is that you have a very small radius in your cross sections that is leading to some of your issue in trying to shell this model.  If you really need that sharp corner, you need to divide those cross sections and make them meet at a sharp corners, then add a small fillet after you have it shelled.  See the red line in the curvature analysis tool.


                                Those are a couple of areas to look into and should get you further in your quest.