10 Replies Latest reply on Dec 5, 2014 12:20 PM by Mike Childers

    Concentric Mate tolerances?

    Mike Childers

      Is there a way to do a concentric mate that is "close".  Because of decimal round off error or mm to inch conversion sometimes a distance between mating parts will be, say, 1.0625 on one part and, say, 1.063 on the other, and the two holes will not concentrically mate.  Is there a tolerance function that I don't know about?  The real world is seldom exact and I can't believe this is not a common problem.  There should be some type of "tolerance" check box that would allow a mate as long as it is within a certain distance.  This would be similar to slot mate, but in two directions.  If this is not available, this would be a good suggestion for future upgrades that, at least, the concentric mate would have a tolerance field.

        • Re: Concentric Mate tolerances?
          Kelvin Lamport

          Submit that idea as an Enhancement Request via the Customer Portal if you feel strongly about it.

           

          Personally, I prefer having exact concentric mates. On several occasions they have proved useful in exposing a mismatch of dimensions or misalignment.

          • Re: Concentric Mate tolerances?
            Glenn Schroeder

            I agree with Kelvin in that I want it to show an error if they won't align.  If this tolerance was implemented I'd want a way to turn it off.

            • Re: Concentric Mate tolerances?
              Mike Pogue

              You can always enter the dimension in mm, regardless of whether you are working in inches. The problem goes away.

              • Re: Concentric Mate tolerances?
                Jamil Snead

                I can understand both sides of the issue. On the one hand it would be nice to have tolerance because as you said holes might not line up perfectly if values were rounded, or maybe it is even intentional. But the clearance in the thru hole would allow slight misalignment. On the other hand, I don't know how SW would solve the position if tolerance is allowed, because there would most likely be multiple positions that satisfy the tolerance. Lets say the holes were perfect but you had tolerance there, would the pieces be allowed to move around relative to each other? Because of those issues, I think I lean toward thinking it wouldn't be very useful.

                 

                When I have hole patterns that don't quite match, which for me usually happens when I'm using a model someone else built where they measured a part with calipers instead of actually looking up the right hole spacing, I just mate one of the holes concentric and then use a parallel mate to orient the parts.

                  • Re: Concentric Mate tolerances?
                    Mike Childers

                    Yes, it would be allowed to move around just like it would do in the real world.  It would be no different than the way the slot mate works currently.  You can select free constraint in that mate and it will slide around just like in real world.  I would do the tolerance concentric mate the same way.  Have a free constraint option, and maybe a "closest" option that would fix it as close as possible to center.  And again, if you made the tolerance zero, it would act exactly like it does now making both sides happy.

                      • Re: Concentric Mate tolerances?
                        Glenn Schroeder

                        Mike Childers wrote:

                         

                        Yes, it would be allowed to move around just like it would do in the real world.  It would be no different than the way the slot mate works currently.  You can select free constraint in that mate and it will slide around just like in real world.  I would do the tolerance concentric mate the same way.  Have a free constraint option, and maybe a "closest" option that would fix it as close as possible to center.  And again, if you made the tolerance zero, it would act exactly like it does now making both sides happy.

                        Couldn't you accomplish the same thing with a Limit Distance mate?

                          • Re: Concentric Mate tolerances?
                            Mike Childers

                            I don't know.  I'll try it.  But that would essentially be what I'm saying, I guess.  Two axis lined up within .001 (or whatever).  I don't normally mate with axis.  I usually keep temporary axis turned off as it really clutters up the screen (and it's one more button to push to turn it on and off), but it sounds like that is essentially what a concentric mate with tolerance would be, an axis limit distance mate.