12 Replies Latest reply on Aug 21, 2012 11:06 AM by Roland Schwarz

    Tangent to a spline

    Pet Peever

      Hi,

      In this file, I have a given spline, which is fixed and the tangent at the origin.

       

      (Btw, I am wondering why I can fix the tangent at origin : if the spline is fixed, the tangent at any point too, but it's not the matter of my post)

       

      I want to define a segment, being tangent at the origin.

       

      So, I draw a segment, one point at origin, the other free, and I define a tangent property.

       

      And I get what is on my screen.

      How can I build this totally elementary construction ?

       

      OK, I can declare some colinearity with the tangent of the spline.

       

      But this kind of behaviour is surely totally normal ?

        • Re: Tangent to a spline
          Alin Vargatu

          What do you mean by "I have a given spline, which is fixed and the tangent at the origin"? Do you want the spline to be tangent to a line that passes through the origin and is vertical?

           

          If that is the case, see attached file.

           

          spline tangent.jpg

          • Re: Tangent to a spline
            Roland Schwarz

            As near as I can tell, it's just a malfunction of sorts.  When I erase the line and draw a new one, tangency works no problem.

            • Re: Tangent to a spline
              Bjorn Hulman

              Pet, you seem to be having a lot of user based issues. Are you new to SolidWorks? Why are you fixing all the points on your spline? Use construction geometry, define you sketch with dimensions. Spline handles can be dimensioned with length and angle. Each point can be dimensioned also. Fixing a point is a great way to stop something from moving while you dimension the rest. Perhaps start asking about what you could be doing better rather than elluding to software shortfalls. I was going to tidy up your sketch, but it'd be best to start again, there is no inherent intent, again the use of construction geomtry would help.

                • Re: Tangent to a spline
                  Pet Peever

                  Hi,

                  I am fixing the whole spline, after a drawing from scratch (the freeform feature, with a spline).

                   

                  I am fixing it to stop something from moving, as you say too.

                   

                  Perhaps this drawing isn't in the accademic SW touch, but it's in the general academic purpose, about one curve and one tangent line.

                   

                  It's really odd that, when I fix the spline, its tangent stays in blue, and if I declare another line as tangent, this behaviour happens.

                   

                  Sorry, but there are some bugs somewhere in the code. And the word "bugs" is here in the plurial form.

                    • Re: Tangent to a spline
                      Bjorn Hulman

                      Pet, how long have you been using SolidWorks for?

                       

                      Every problem has a solution.

                        • Re: Tangent to a spline
                          Pet Peever

                          HI,

                           

                          I am using SW for perhaps 3 years, but only some weeks per year, for my holidays.

                          And mecchanic isn't my field, btw .

                           

                          Here, it's the Summer Edition which makes me come back here : I want to check some simulations, about the assemblies and composite ones, particularly, which seem very powerful, and aren't in the student version,

                           

                          What makes me sometimes grumbling is about the math rigour of the program : if I can give my 2 cents, I also tried tflex, which is less comfortable, to draw from scratch with the mouse (to grab points and curves are less powerful), but the math of the basic constructions are much more pleasant : the program asks me about what I am expecting the program has to ask something, to go further.

                           

                          If SW has such option about choices, hidden somewhere, I wish i knew it, really.

                    • Re: Tangent to a spline
                      Rick McWilliams

                      Fixing a spline does not necessarily fix the end points. Make spline proportional and set end points may stabilize your sketch. I get best results from the spline shape on one sketch, and a second sketch on that plane that copies the spline as convert entity and has tangent features and appropriate trims. The tangent relation can get stuck off tangent. I delete the relation and redo it. One of the many really silly SW bugs that have been around since 2007.