5 Replies Latest reply on Dec 11, 2018 3:41 PM by Shawn Stugard

    center of mass symbol location incorrect?

    Melvin Donahoo

      Using 2017 SP 5.0, I have an assembly that I've been tracking CG, mass and inertia's since creation since this is a rotating mass. I'm at the point where I'm making a drawing to aid in balancing and I've created a center of mass symbol which is an option in the mass properties window.The center of mass symbol was not created at the coordinate location as stated by the CG mass props. After a long and tedious investigation I found that the hidden but not suppressed parts in my assembly were causing the shift. Therefore the center of mass symbol that SolidWorks creates uses hidden parts in the calculation and the mass properties table does not unless you check the box to include them.

       

      My question is have other users found this to be true? I'm not sure I like this functionality especially when you can run mass props with parts simply hidden. At the very lest I'd like to see this explained in the help popup for mass props. I personally don't like keeping certain parts suppressed if I have active parts that are mated to them.

       

      Mel

        • Re: center of mass symbol location incorrect?
          David Matula

          hidden parts are hidden so that we can see what is behind them.  They are not hidden to just not be in the assembly.  If they are not needed then delete them or suppress them and then 90% of your problems go away.  Hiding parts was not available and made looking threw some assemblies more fun that it needed to be.  Now it is easy to hide them but you have to remember how the program works and why that was added for display states and to allow users to get into the middle of an assembly to work on parts add more parts ect. 

           

               why would you want active parts mated to parts that you do not intend to use?

            • Re: center of mass symbol location incorrect?
              Philippe Vallee

              I have a model with cone of light (an optomechanical design). The cone a light is usefull to define baffles but it has no weight ! Still it drives most of my assembly. I generally don't wan't to suppress them just hidding them so SW doesn't take care of their weight would be usefull.

                • Re: center of mass symbol location incorrect?
                  Glenn Schroeder

                  Philippe Vallee wrote:

                   

                  I have a model with cone of light (an optomechanical design). The cone a light is usefull to define baffles but it has no weight ! Still it drives most of my assembly. I generally don't wan't to suppress them just hidding them so SW doesn't take care of their weight would be usefull.

                   

                  Create a custom Material, with the Mass Density set to very close to zero (0.00000001, or something similar).  Assign this Material to your cone, and it's weight will be very close to zero, so it shouldn't throw your Assembly CoM off..

                   

                • Re: center of mass symbol location incorrect?
                  Glenn Schroeder

                  David Matula wrote:

                   

                  hidden parts are hidden so that we can see what is behind them. They are not hidden to just not be in the assembly. If they are not needed then delete them or suppress them and then 90% of your problems go away. Hiding parts was not available and made looking threw some assemblies more fun that it needed to be. Now it is easy to hide them but you have to remember how the program works and why that was added for display states and to allow users to get into the middle of an assembly to work on parts add more parts ect.

                   

                  why would you want active parts mated to parts that you do not intend to use?

                   

                  Some of us hide components that we don't want to show in selected drawing views.