8 Replies Latest reply on Jan 23, 2013 9:48 AM by Christopher Figgatt

    Re: Advice on modelling 3-d Bike Frame using Sweep and Path

    Aidan Meagher

      Hi

       

      I am having some issues when it comes to modelling a given Trials Bike Frame for a final year engineering project. My problem is that i cant find any examples of how to model it using a matrix method i was told about.

       

      I have the frame and need to re-create it in Solidworks, all examples i can find are creating a frame rather than re-creating it. The frame itself has almost no staright sections and curves in 3 dimensions. It also has 2 different sized elliptical sections, which i know the dimensions of. I had been told to take a (0,0,0) (datum) somewhere on the frame and measure the x, y andz distance every 10-20mm along each portion of the frame, and then somehow input these values into Solidworks in matrix form. And subsequently using these points that the software can find the path required to sweep this section along (ie-splines?). I am aware of the fact that it is possible to create these paths myself but in reality measuring them accurately enough is extremely difficult.  

       

      Although i am an absolute novice when it comes to this programme, i have some experience with Pro-E and AutoCAD. Perhaps someone could tell me the correct name of the tool i am looking for or a good resource for finding a worked example from which i could get some tips from.

       

      Thanks

       

      Aidan

       

      PS- My terminology may be completely wrong, please excuse my lack of knowledge when it comes to Solidworks.

        • Re: Advice on modelling 3-d Bike Frame using Sweep and Path
          Christopher Figgatt

          I believe that the tool your looking for is under Insert > Curve > Curve Through XYZ Points. You can also use this function to import an Excel spreadsheet with the point data.

          • Re: Advice on modelling 3-d Bike Frame using Sweep and Path
            Dave Laban

            Presumably we're talking about one of the super-low slung Koxx / Onza style frames where the top tube and down tube are virtually coincident?  Might be worth linking to some pictures so anyone not familiar with the design can offer some useful surfacing advice (surfacing is far from my strong suit, but I'm trying to get my head around it as a side project at the moment).

             

            Bottom bracket shell would probably make the most sense for 0,0,0 location.  Overall angles (head tube, effective seat tube etc) and lengths (wheelbase, chainstay etc) should be available from the manufacturer site.  I've used this data to create a sketch around which I modelled a frame before, at least to get the initial proportions right.

             

            As Christopher mentions though, Curve Through XYZ will achieve the method you've suggested.  I think the SolidWorks help/tutorials cover lofts and sweeps quite well.  Or at least, well enough to allow experimenting afterwards.

              • Re: Advice on modelling 3-d Bike Frame using Sweep and Path
                Aidan Meagher

                Dave

                 

                Thank you for the response, i will upload some photos of the frame and model once i get it done.

                 

                You mention the bottom bracket being a good place to start, my major issue is that there is no bottom bracket. The frame i am working on is a Gas Gas Trails bike frame, and the project being that the petrol motor has been removed and is being replaced by a DC Brushelss Permanent Magnet Motor. So the engine was formerly a stressed member and my motor mount must replace this. So i think the (0,0,0) will have to be in the head tube, which is not a problem.

                 

                So my plan is too find the path for one half of the frame and mirror, as it is symmetrical. And add each bracket as i go, there are many braces and brackets along the backbones and around the rear pivot point for the swing arm.

                 

                Again many thanks.

                 

                Aidan

                  • Re: Advice on modelling 3-d Bike Frame using Sweep and Path
                    Dave Laban

                    No problem!

                     

                    I had in my mind pedal-bike trials frame rather than something with an engine, but then again stripping the engine out changes the problem again too!  Head tube definitely sounds like the next best option.

                     

                    Sounds like an interesting project to be working on, I would have thought getting large amounts of power for short amounts of time out of an electric motor would be tricky, mainly from a power source point of view.  I guess ruggedising the batteries could be fun too!

                     

                    Will be intrigued to see any images you can provide when the project develops

                     

                     

                    Edit;

                    Another thought, do you have any access to 3D scanning facilities at your University (presuming you're at Uni as you mentioned it's a final year project)?  As you may be able to use those facilities to at least get the bulk of the frame shape imported digitally, meaning it should only need fine-tuning in SW.  As it sounds like it's more of a design project than a learning-SolidWorks-project, it may be a way to get going quicker and gain some credit for using all available resources!

                • Re: Advice on modelling 3-d Bike Frame using Sweep and Path
                  Daen Hendrickson

                  Without knowing the particulars...

                   

                  Curve through XYX points to import your tube paths. Create two weldment profiles for your two eliptical tubes. Use weldments to create the paths.

                  • Re: Advice on modelling 3-d Bike Frame using Sweep and Path
                    Christopher Figgatt

                    While this may not relate directly to your original question, I thought this model from the SolidWorks Surface Modeling class had some interesting concepts for blending tube type shapes together.