5 Replies Latest reply on Mar 8, 2011 10:30 AM by Charles Culp

    3 way loft issues?

    Peter Blais

      Hello guys. I've been working on this curvey intake manifold plenum for a while. I've got it done at the moment (see pics) but the problem I'm having is that I am trying to optimize it in CFD, and I can't adjust it at all without it crashing and not rebuilding. I used a fill surface on this boot portion, and it worked perfectly, but it's right on the borderline of not working. If I tilt the outlet 5 degrees, it won't work, move it up or down an eigth inch, it doesn't want to work.


      Anybody have a suggestion on an alternate / more rebuild friendly way to do this?





      The other problem is that I have to thicken this .1875", and even if the fill rebuilds, a lot of times the thicken will not work.



        • Re: 3 way loft issues?
          Scott McFadden


          It has been a couple of years since I have done surfacing, but a couple of thoughts that

          come to mind is one how about thickening the part to a solid then shelling it.

          Second, I know Matt Lumbard and Charles Culp are very good at surfacing and could

          most likely give you a great answer.  I know Matt has some book on surfacing.

          Charles has done surfacing presentations at SWW and if you look on the SWW portion

          of the forum and under presentations you can download them and maybe pickup

          some tips.

          Good luck and I hope I gave you something to chew on.


          Oh, and welcome to the forum!!! 

          • Re: 3 way loft issues?
            Kevin De Smet

            I would divide it up into two surfaces, a surface doesn't like bending over backwards, if that makes sense. I'm surprised you even got a fill to work like that, I couldn't! My attachment isn't perfect but should give you a fair idea on how to break it up.

            • Re: 3 way loft issues?
              Robert Stupplebeen

              I would model one half and mirror for the final geometry.  Make sure that the surfaces are perpendicular to symmetry plane or there will be a peak or cleavage when you mirror.  You may also want to cut it into multiple surfaces.  On the CFD side only simulate half of the model to reduce computational time significantly.  I hope this helps.


              Rob Stupplebeen

              • Re: 3 way loft issues?
                Peter Blais

                Thanks a LOT guys... I had already tried to split in in half, but for some reason didn't think of making the extra extruded surfaces to start from... That was the key I was missing.


                I did end up quartering it, and making the top two pieces out of two boundary surfaces, because otherwise my surface had a few lumps in it I could not get rid of. After that though, smooth sailing, and now I can change my model.


                I only got the one big fill to work before by sheer determination. I think I annoyed solidworks into making it work.


                I can't use symetry on the CFD because the plenum bolts onto a lower runner assembly which is not symetrical, but it's OK, good excuse to get a new PC.


                Also, thanks for pointing me to shell, instead of using thicken. It seems to work a lot better. This is good, as I have about 3 more projects like this, and prior to this I had only modeled up square / chunky machined parts.


                Thanks again guys!