3 Replies Latest reply on Dec 21, 2009 10:19 AM by Harold Brunt

    Constraint of Splines, Preferred Method?

    Chris Dolejska

      Regarding the constraint of splines, what are the methods and what is the preferred method?

       

      (splines with 3 or more points)

       

      Usually the ends are restrained first. Like with tangents to straight lines or tangents to other splines. Or by coincedent end points with other entities then horizontal or vertical constraints on the end spline handles.  Then sometimes the rest of the spline is left unrestrained (all the intermediate spline points).

       

      Sometimes the intermediate spline points will be fully constrained with 2D dims to each spline point and a length and angle dim on each spline handle. But this seems very time consuming.

       

      Is it common to just restrain the ends and then"fix" the entire spline thus fixing all the intermediate spline points and handles? But sometimes when you do this it becomes over-constrained and you have to "fix" each individual intermediate spline point.


      Guessing it depends on the application, like an artistic designer would leave the intermediate points unconstrained and someone designing an auto fender die would do the fully dimensioned method?

       

      Are there other methods/preferences?

        • Re: Constraint of Splines, Preferred Method?
          Charles Culp

          I generally leave my splines unconstrained. I only constrain those points/tangencies that require constraints. Because my splines are typically in different sketches, or if they are they are not constrained to each other. This way modifications to one spline don't effect the others.


          There are just too many constraints to apply to splines to do it any other way. I have used the "fix" constraint when I want to adjust multiple splines in the same sketch.

          • Re: Constraint of Splines, Preferred Method?
            Dan Riffell
            I tend to leave my splines unconstrained except for specific relations that are necessary.  If you're working with a particularly long spline or a sketch that has multiple splines, fully defining the splines will add a lot of time to your rebuilds.
            • Re: Constraint of Splines, Preferred Method?
              Harold Brunt
              I think you have it right on the mark with "it depends on the application". I get pretty frustrated with splines so when I get them where I want them I fix the points. Once in a while I will generate a DT to dimension a spline if I am using a conic that needs to be controlled using a Rho value and it will be edited frequently. I try to avoid splines as the surfaces generated using them are not as accurate as those generated using the sketch tools available in the menus.