19 Replies Latest reply on May 15, 2018 4:47 PM by James Harvey

    piston travel distance issue

    Riley Chrisman

      Having an issue trying to figure out how to keep a piston from traveling too far from the base. Have a concentric mate with the piston guide, mate from the guide to the top of the piston with the max distance set, and a linear coupler from the piston top to the set screw that pushes it down. What am I doing wrong?Capture.PNG

      It will let follow the set screw down and up but wont let me rotate to the other side ( any further than the piston is allowed to go up).

      Very new, self taught, so sorry if this is super simple, thank you.

        • Re: piston travel distance issue
          Dan Pihlaja

          Can you share the assembly? (hint: use pack and go to create a zip file)

          • Re: piston travel distance issue
            Dave Bear

            Hi Riley,

             

            I have had a look at your assembly and I think that this could be quite easily solved, but firstly I'm curious about a few things. Why are your top set screws not aligned (concentric) with your pistons? Not that they have to be of course, I just thought it was odd!

             

            Also I noted that the two top set screws are not symmetrical in their spacing from the centre, evidence of this is the obvious fact that in the real world you would not be able to turn the far locking nut as it already collides with the top housing. I do not mean to sound critical, I am a beginner also and self-taught, I just thought I'd point these out to you.

             

            Dave.

            • Re: piston travel distance issue
              John Stoltzfus

              Distant mates work if you set the minimum and maximum values from points, surfaces or planes, however if you mate using spherical bodies or faces, they could jump across the center line.

                • Re: piston travel distance issue
                  Riley Chrisman

                  Distance mates work to a point, but once the piston reaches max distance from the guide it holds the handle base back from pivoting any further, i need the piston to come up when you tilt the handle base back but stop once it gets to a certain point and allow the handle to rotate to the other side to push the other one down. I attached an updated assembly so you can see what i have right now.

                    • Re: piston travel distance issue
                      J. Mather

                      It is my opinion that you should put the assembly aside for a while and go back to concentrating on part modeling.

                      I opened your part HANDLE BASE.slprt and find that Sketch1 is not fully defined.

                      This part has a lot of symmetry, yet no use was made of that obvious symmetry in the modeling of the part.

                       

                      Good assembly modeling is heavily dependent on starting with good part modeling techniques.

                      (I saw a lot of other potential issues as well, Sketch1 is a good place to start with disciplined, robust modeling techniques.)

                       

                      Use Symmetry.png

                      • Re: piston travel distance issue
                        J. Mather

                        No fastener can be screwed into this thread and I recommend that you avoid bottom tapping a hole. (broken taps will result)

                        No Fastener.png

                        • Re: piston travel distance issue
                          J. Mather

                          This would have been a good place to stop and ask questions here.

                          I don't think this is what you really intended for your design.

                          I very rarely create any workplanes - I almost entirely use the Origin Workplanes (especially for geometry this simple).

                          Are you familiar with the BORN Technique?

                          What book or other resource are you using to learn SolidWorks?

                           

                          Work Planes.png

                            • Re: piston travel distance issue
                              Riley Chrisman

                              Just figuring it out on my own, it wasn't meant for a production part, but more of a learning project.

                                • Re: piston travel distance issue
                                  J. Mather

                                  Riley Chrisman wrote:

                                  Just figuring it out on my own, it wasn't meant for a production part, but more of a learning project.

                                  OK, so let's start out on the right foot in learning SWx (or any CAD program).

                                  Bit of background - I have been from the shop floor to the drawing board to the CAD seat for nearly 40yrs.

                                  I have seen numerous examples over the years of beginners getting started on the wrong foot and then many are not able to break bad habits. 

                                  I know you are just trying to learn the program, but you should always always always keep Design For Manufacturability (DFM) at least in the back of your mind if not out in front. 

                                   

                                  So let's get started (this all can move very fast if you follow along).

                                  Open the part PIN.sldprt.

                                  Edit Sketch1.

                                  Note that you created a circle out in space with no use of a datum.

                                  When the person out on the shop floor goes to make this part - the first thing they will do is establish a datum.

                                  Now if that is the first thing they will do - why is it hard for the designer?  No excuses.

                                  In fact, it is trivially easy and will make your life easier when you get to assemblies.

                                  Drag the center point of the circle to the origin.
                                  Note the color change of the circle (from blue to black letting you know that the circle is fully defined).
                                  You could have created the original circle at the origin - so this is absolutely no extra work and will eliminate future extra work.

                                   

                                  But since I mentioned DFM, you have a pin Ø.5 that goes into a hole of Ø.5 , that is not going to work in the real world. We cannot manufacture perfect parts, and even if we could, and we could inspect down to the atomic level - if there are atoms on the .5 circle on the pin and atoms on the .5 circle on the hole - then atoms will have to move out of position to allow assembly.  An arbor press would be required to impose this necessary force.

                                   

                                  I see a lot of beginner designers try to model "perfect parts" for assembly.  Always consider the real world - realistic clearances and tolerances, then you will be designing perfect parts (that can actually be manufactured and assembled).

                                   

                                  Double click on the .5 dimension and change it to .495 (it is easier to make cylinder of any needed size than hole).

                                  When you have completed this step, then I will suggest next change.

                                  If you don't follow my instructions, when you get to the real world - you will experience great difficulty with your co-workers.  It is critically important to develop good practices right from the first step.

                                   

                                  Use Origin.png

                            • Re: piston travel distance issue
                              Dennis Dohogne

                              As John said, the limit distance mates work best when they are referencing flat surfaces.  Also, if you need the parts to behave a certain way when something else is done, such as when you tilt the handle base, then perhaps you need a different definition or set of definitions.  You can have multiple limit mates in an assembly.

                            • Re: piston travel distance issue
                              J. Mather

                              Riley Chrisman wrote:

                              Very new, self taught, so sorry if this is super simple, thank you.

                              The PIN part would be a good place to start if you would like to get some pointers on how the pros use SolidWorks.

                              Let me know and I will demonstrate how I would fix that part.

                              • Re: piston travel distance issue
                                Dave Bear

                                Hi Riley,

                                I just want to add something here. Don't take anything that's being said here as severe criticism. The guys are only trying to get you off on the right track from the get-go! Whilst you might just prefer an instant fix to your problem (and say so if that's your desire), getting some guidance from experienced people on design intent, workflow, method etc. might just make all the difference to all of your future projects. They're sharing info you just might not read anywhere and with the best intentions and I just didn't want you to misunderstand that.

                                 

                                Dave.

                                • Re: piston travel distance issue
                                  Dennis Dohogne

                                  Riley Chrisman,

                                   

                                  Welcome to the forum and to SolidWorks.  You will get great advice here and already have, i.e., learn about Design Intent and DFM.  Learn about the processes that will be used to make the parts you are modelling.

                                   

                                  As far as learning SolidWorks, you will do yourself a world of good by just going through ALL the tutorials:  open SWX, go to Help -> SOLIDWORKS Tutorials.  They even provide an estimate of the amount of time it should take for each module.  It is by far the fastest and most available way to shorten your learning curve.  Enjoy!!

                                  • Re: piston travel distance issue
                                    James Harvey

                                    I'll add my .02 worth for a new user. I'm not sure if you plan to make a career of it so take it for what it's worth.

                                    This is something that tutorials and classes didn't cover the importance of when I was learning the software -

                                    Solidworks files of any given type (.sldprt, .sldasm, .slddrw) should each have it's very own unique file name!

                                    I cannot emphasize that enough!

                                     

                                    Different SW file types can share the same name, but I would only allow that between a .sldprt file, or a .sldasm file, and it's corresponding .slddrw file. And in some cases I would avoid it there as well.

                                    "File Referencing" can become a BIG problem if you store Solidworks files in multiple Windows folders and allow duplicate file names to exist. I have learned this the hard way and it still bites me occasionally. Develop a good naming convention and treat it as law.

                                     

                                    Expensive PDM (Product Data Management) programs can prevent the problem by simply not allowing it. I don't have access to PDM so I can't say much else about it.

                                     

                                    Enjoy learning a great, very powerful, and very often fun tool!

                                     

                                    Best,

                                    James