15 Replies Latest reply on Dec 3, 2015 2:13 PM by Kevin Chandler

    greater than dimension

    Alan Mogg

      I wondered if im missing something simple but how can i create a greater than dimension, i.e an angle not less than 5 degrees for example, or a length greater than 10, this being a sketch dimension driving a part not a dimension in a drawing.

       

      apologies if i have missed something obvious, and thanks for any advice

        • Re: greater than dimension
          Glenn Schroeder

          I'm not aware of any way to do that.  Maybe if you could explain a situation where you need that someone could suggest an alternative method.

            • Re: greater than dimension
              Alan Mogg

              Im designing a rubber part which essentially controls a kevlar braided line that runs through it, the rubber part basically pleats the kevlar core when its contracted to keep it within a certain envelope, the pleats are made of three circles in sort of double S shape, where the tip of the S meets the body of the part i want to be able to say the angle can be anything greater than 0 degrees other wise the sketch fillet will fail. I've come up with the solution of using trig to calculate and drive the sketch fillet value, but it i already have to gently alter the overall length in 50mm increments other wise it fails, and i also have to ctrl q every time i change the equation then go back in and alter it another 50mm which is time consuming.

            • Re: greater than dimension
              Mike Price

              Under the "Dimension Text" dialog, select "More..."

               

              Then select "Character Map".  You can then select your font (Arial or whatever) and then scroll down to find more symbols than you cared to know existed.

              • Re: greater than dimension
                Deepak Gupta

                Not do able in drawing but only models AFAIK. You could create the sketch in the model and then reference that in drawing.

                • Re: greater than dimension
                  Mike Price

                  Alan,

                   

                  What you could maybe do, depending on your geometry, would be to establish construction geometry that would not allow your sketch to solve correctly if you hit a certain number.

                  • Re: greater than dimension
                    Chris Michalski

                    Are you trying to make a dimension that can't be set less than 5 degrees?  Or are you trying to leave a dimension undefined as long as it is 5degrees or greater and let SW solve for it as you move things around?

                    For the first I'd set a variable equal to 5 and then define your dimension as an equation of dimension A plus that variable.

                    For the second if it's possible I can't see a way to do that.

                    • Re: greater than dimension
                      Scott Harvey

                      There are lots of things you can use in equations like if then statements but without knowing exactly what is driving your function with what geometry its hard to specify.

                       

                      If you can't upload your file, screen shot the the geometry you are trying to drive to not be below 0 degrees.

                      • Re: greater than dimension
                        S. Casale

                        You seem to be asking about tolerances.

                         

                         

                        If you want a dimension that can be 5º more or less than 5º than your dimension would look like this:

                        (symmetric)

                         

                        If you want your dimension to be no less than 5º but can be greater, it is a best practice to assume a max acceptable.

                        An example of this would be:

                        (bilateral)

                        You could select the Min:

                        • Re: greater than dimension
                          Tom Searight

                          Hi Alan,

                           

                          Not an answer I'm afraid but I think I have the same question:

                           

                          I have an assembly with a flexible PCB that runs between two parts.  Due to manufacturing tolerances the distance between these parts will vary.  The PCB must therefore be at least as long as the max distance - so far easy enough.  I need to model the PCB at min part spacing to ensure it will bend enough while still fitting in the available space.  I have modeled the path assuming that this can be taken up with a single kink as shown:Sketch.png

                          Adding a path length dimension means that the free length of the PCB is fixed while the point to point dimension (87 on the sketch above) can be varied.

                          However there are some constraints:  The PCB must not have a bend radius tighter than 4mm and there is a limit of 5mm on the vertical space the PCB can occupy. (shown as the 4mm and 5mm dimensions above).

                          So logically this should be very easy:

                          Path length = 90

                          vertical height =< 5

                          R1 >=4

                          R2>=4

                          R3>=4

                           

                          The point to point dimension could then be changed over the required range and if the sketch can be solved I would know that the change in length can be accommodated.

                           

                          But this would require using a > and < operator in an equation and I cannot see that this is possible.

                           

                          Any help welcome.

                          • Re: greater than dimension
                            Thomas Bernert

                            Would it be acceptable to just be informed if the demension leaves the allowable region? Have you considered using a sensor with an alarm?

                            • Re: greater than dimension
                              Kevin Chandler

                              Hello,

                               

                              A bit of extra input, but what about using custom properties for your input values.

                              Then in Manage Equations, use conditional if statements in global variables to check for data validation.

                              The sketch dimension then references the global variable.

                               

                              For example:

                              Custom property: LENGTH, set to 10

                              Global var: LengthMax, set to if(LENGTH>15, 15, LENGTH)

                              Sketch dim: =LengthMax

                               

                              Then alter your properties' values in Custom Properties (at least for those that require data validation) to adjust your sketch.

                              The global vars will catch out of range entries but still provide workable data for the sketch.

                               

                              I hope this helps.

                               

                              Cheers,

                               

                              Kevin

                              • Re: greater than dimension
                                Casey Bergman

                                Look into sensors.  It will still let you enter the dimension as longer but will flag the user that there is an error with a caution symbol and a tone.

                                  • Re: greater than dimension
                                    Kevin Chandler

                                    Hello,

                                     

                                    Following on Mr. Bergman's post, if you wish to flag an out of bounds condition and still use the method I previously posted, then perhaps set the out of bounds conditional to cause an equation error.

                                     

                                    For example:

                                    Custom property: LENGTH, set to 10

                                    Global var: LengthMax, set to if(LENGTH>15, LENGTH/0, LENGTH)

                                    Sketch dim: =LengthMax

                                     

                                    This will invalidate the global var, turning "Equation" in the tree to red.

                                    You'll have to decipher the global variable definition to understand the error.

                                    Might blow up other things as well.

                                    And, unlike sensors, there's no nice messaging.

                                     

                                    Just a thought.

                                     

                                    Cheers,

                                     

                                    Kevin