11 Replies Latest reply on Jan 26, 2009 3:56 PM by Mark Biasotti

    Knit to solid-manifold surface bodies

      When I finish creating a manifold surface body (MSB) to turn into a solid, I often am faced with the "Cannot knit surface to itself" error. To solve this, I copy a face, hide the copy, and delete the original. I then have 2 bodies that the knit tool will accept, and make solid. This adds one surface offset, and one delete face per body. This usually happens when the last feature used to create the MSB was a trim feature, which is quite often.

      Is there a better way to do this that I am missing?

      Perhaps the surface trim tool could recognize post-trim manifold bodies and offer an option to knit them to solid? Perhaps the knit tool could be expanded to be able to handle a single, multi-faceted surface body for a conversion to solid geometry?

      It's not a big deal, but with surfacing, I am always trying to cut down on my feature count.

      Any thoughts?
        • Knit to solid-manifold surface bodies
          Charles Culp
          Use the thicken command Insert>Boss/Base>Thicken... If it is a closed manifold, then it will give you the "create solid from enclosed volume" option; which is the proper tool to use in this occasion.
          • Knit to solid-manifold surface bodies
            Matt Lombard
            SolidWorks probably considers it a productivity enhancement, but I consider it a bug. When you finish a Trim and then make another Trim, SW automatically adds the finished product of the previous feature as the trim tool for the next feature. The problem is it doesn't highlight the selected body, so you might not notice that its selected.

            This might also be happening with Knit, inadvertently causing the error. You have to have more than one surface body selected for the knit feature. Other wise use 0 distance offset.

            There are some features that can move directly from surface to solid. The Fill surface will knit and make solid. Knit will also solidify. Other similar features do not have these options. Weird interface inconsistencies. I don't report it as a bug because SW would probably remove the good functionality and call it bug fixing.

            • Knit to solid-manifold surface bodies
              Mark Biasotti
              Will, could you please post an image and/or example. I'm trying to get a image of this and would like to understand. If it's a shortcoming or bug on our part, I'd like to capture it.

                • Knit to solid-manifold surface bodies

                  Here is a basic example that I hope helps you. I would't describe this as a bug, it is more of a small productivity shortcoming that could be improved.

                  You can see in the model that a mutual trim yields two separate, manifold surface bodies, but sometimes I will use the trim feature to create 50-100 MSB in a single feature. For example, the tread on the bottom of a shoe. Using the thicken tool (thanks Charles!) this means a thicken feature for each body.

                  What I am thinking is...

                  Why can't the surface trim feature recognize my two MSB's and ask if I wish them to be converted to solid? It seems as if the tools are there, but not in the right places.


                  Thanks, but I don't think this is related to the "pre-selected but not highlighted" "quirk" that surface trim/knit/offset have. Originally I was wondering why the knit tool cannot handle single, multi-faceted surface bodies, and Charles answered by pointing out that there is a better, more appropriate tool to use.

                  Now, however, I am thinking out loud about the surface trim tool thickening for me in a more automated fashion. Fill is usually not appropriate for me because I don't have enough control over the geometry it produces.
                    • Knit to solid-manifold surface bodies
                      Mark Biasotti

                      I understand that you want the Mutual Trim tool to go the way that the knit tool has and have an option that "tries to form a solid" as part of the mutual trim Property Manager.

                      I have to ask you why are you so eager to make so many separate solid bodies for the hundreds of sole tread details so early on, when in the end you have to get to one solid body? Why not complete all the tread details as open surfaces and then do a massive mutual trim against the intersecting main surface or solid. That way you'd only have to do one thicken. I guess I'd have to see a more complete shoe example of what you're trying to do to appreciate this.

                      I think I can do you one better that you'll might like even more. What if we had the ability to intersect a open surface body with a solid body and make solid the surface body solid automatically as part of the existing intersecting solid. In other words, if a 5 sided cubed-shaped surface body was protruding from a solid with the open face buried in the solid, the software would recognize that the combination, if combined would result in one manifold solid. I can invision this for what you're trying to do and would be a great enhancement. In fact I've been pushing Dev to do this for a number of years since ProE has done this all along.

                      Think about it, and then please submit an online enhancement request for your original idea and/or the intersecting surface/solid combine approach.