9 Replies Latest reply on Jun 23, 2009 3:31 AM by John Sutherland

    Concave fillets destroy construction lines

    John Sutherland
      I require that my finished profiles be checked/audited for compliance with design intent (i.e. standards).

      Convex fillets cause me no grief but concave fillets destroy the construction lines and dimensions which are evidence of how I created the profile.

      I can substitute tangent circles for concave fillets but have not found a way of joining the entities between tangent points.

      I hoped Fix Spline would do that but it objects to self intersecting contours.

      Suggestions please.
        • Concave fillets destroy construction lines
          Matt Lombard
          First of all, there is no difference between concave and convex in a 2D sketch. In order for there to be a difference, you have to understand the inside from the outside, and sketch fillets certainly don't do that.

          Sketch fillets always trim, because the assumption in a SolidWorks sketch is that you are trying to make a closed profile. Maybe that's old-fashioned, but that's the way it is.

          If you want extended construction lines, your best bet is as you have done, to make circles (using radial rather than diameter values), but then continue on and trim the circle so that the arc (fillet) is all that's left.

          If that doesn't answer your question, could you be clearer with the question and possibly mark up the sketch with the area in question?





          • Concave fillets destroy construction lines
            Anna Wood
            John,

            Is this what you are trying to do? Just add additional sketch lines and constrain appropriately. Collinear works well.

            I changed the sketch colors to pink for the added line segments in the attached image and sldprt file.

            I do this all the time with stuff I create where I need to control the intersection point and it gets consumed when I add rad's.

            You can also add Virtual Sharps. Search on Virtual Sharps in the SolidWorks Help for info on that feature.

            Cheers,

              • Concave fillets destroy construction lines
                John Sutherland
                Thanks Anna,

                Virtual sharps allowed me to fillet intersections without losing the evidence of how the intersection was made.

                  • Concave fillets destroy construction lines
                    Steve Calvert
                    John, if you notice that when you're sketching lines to create a shape and then make dimensions from intersecting points to intersecting points that these points will remain after you have added sketched fillets. This is why I try and teach this as the way to go when making profiles that need fillets at the sketch because when you add the model items at the drawing level, the skecth dimensions will fall into place.

                    Steve
                      • Concave fillets destroy construction lines
                        John Sutherland

                        Steve Calvert wrote:

                         

                        John, if you notice that when you're sketching lines to create a shape and then make dimensions from intersecting points to intersecting points that these points will remain after you have added sketched fillets.

                        Steve

                        This is not my experience.

                        The images show the intersection disappearing upon filleting.
                          • Concave fillets destroy construction lines
                            Dwight Livingston
                            John

                            I see in your example that the left end of the 0.0360 dimension is dimensioned to something toward the bottom of the sketch. Instead, pick just the line you are dimensioning, or at least pick the point at the end of the line you want to fillet, then you will get a virtual sharp when you fillet.
                              • Concave fillets destroy construction lines
                                John Sutherland
                                Dwight,

                                I am not absolutely sure of what you are suggesting, but I experimented with applying the fillet tool to the intersection point, rather than selecting each of the intersecting lines, and it filleted the acute angle without destroying the construction line and dimension. However I want the obtuse angle filleted.

                                But I can't fillet this way the vertical construction line to the right of the vertical axis of symmetry because SW does not recognise a point at the intersection of that line and the sloping line.
                                  • Concave fillets destroy construction lines
                                    Dwight Livingston
                                    John

                                    I'm saying it matters what entities you pick when you dimension, before you apply the fillets. Say you have a square, and you want to dimension the height . . .

                                    You can pick the top and bottom horizontal lines, and that won't get you any virtual sharps.

                                    You can just pick one of the vertical sides, and that will get you a virtual sharp for the corners at the top and bottom of the line you picked.

                                    You can pick a top corner point and a bottom corner, which will also get you a virtual sharp at those corners.
                                      • Concave fillets destroy construction lines
                                        John Sutherland
                                        Thanks Dwight for clarifying your suggestion. It sounds very credible as it falls into the category of many ways to skin a cat but only one is satisfactory in the end.

                                        I tried it on my rail sketch which has two polygons but no squares, deleting some vertical dimensions and replacing them with your technique. On filleting, the dimensions disappeared.

                                        It worked with vertical ordinates in only one situation.

                                        This is the story of SW. It is so nuanced that using another's suggestion outside of their context will probably fail. I have written virtual sharps into my manual of what works for me.