In this project me and my partner worked on creating the West Point Truss Bridge in the Designing and Building File-Folder Bridges text book. To create the bridge we used CorelDraw for the laser cutting files, we cut the files on the Epilog Fusion pro with chip board, we then super glue to combine all the pieces, testing machines that were already made, and more to help create and test this project. 

Project files 

Links

These are the two links me and my partner used. The first link is to the creation of the West Point Truss Bridge with a step by step process and has more from the text book, the bridge activity starts on page 29. The second link is to the testing of each component and how to calculate tension and compression. 

Link one - https://drive.google.com/file/d/1U-qYN7UlromiVJHNW5YgojewDLzHpwhw/view

Link two - https://drive.google.com/file/d/1LMC12pQCbDvp1IINIDdDsdBUThj_z2NZ/view

Files

Workflows

Epilog Fusion Pro -  https://docs.google.com/document/d/1qD0LRhzoDkfVyfnCCNbM-DmZQnyk_Nr_hm7WTA6FlrM/edit 

Epilog Fusion M2 - https://docs.google.com/document/d/1GOyWMEj3ViTaLE_5XUlAyPPT1OH4zOMdRdKFBexndLw/edit 

Using the laser cutters 

For the gusset plates we cut on the Fusion Pro and imported the cardstock cut and vectored the whole file and at this point we were able to us auto focus on the laser cutter but eventually we had to manually focus it by drooping a plunger on the laser and raising the bed to touch the plunger. For the support beams we used the Fusion Pro and we set the file to vector by color and we imported cardstock cut for the black and cardstock score for the red. From Fab Academy I tested the kerf on the Fusion Pro and determined that the value is so small that in this case there would be no real affect from it. 

Part Processing 

Blueprint

To help plan out the bridge we created a blue print on a sheet of card board. From the West Point textbook included above (page 32), we split the page into 8 pieces of paper and taped them to the card board sheet and then taped a layer of wax paper over so that we could glue and assemble the bridge on the blueprint. 

For creating the support beams we used super glue to hold them together. The process was first making sure to crease the score lines and to create the beam without glue. Then lift the glue tab and apply the super glue and hold the tab down with our fingers that we covered in tape so we didn't get glue stuck to our fingers. In some cases we had to trim the beams to fit, and to do that we layered the piece over the blueprint marked in sharpie where to cut then cut with either scissors or an exacto-knife. 

Constructing the Bridge 

Testing Bridge Components 

To test the bridge we followed the instructions in this West Point Guide. Using the Testing machine and sand as the weight we were able to calculate the mount of force each member could withstand. The members of the bridge under tension apear to break around the middle of the member, while the members under compresion will break almost anywhere. The West Point doc linked above showes how to turn the weight of the sand into Newtons of force for compression and tension and the doc also shows and explains graphs of bridge force distrobutions.

Testing the bridge 

Conclusion 

In this project we created laser cutting files in Corel Draw, a vector based program, cut the files on chipboard. The using the pages we printed and a cardboard back we created a blueprint that we placed our cut chipboard and used super glue and West Point instructions to create the bridge. Then using the West Point guide, we used the testing machine and sand as the weight to test compression and tension forces on members of the bridge. I learned how to test members of a bridge and how to calculate the newtons of force. I learned how to calculate the load on each member if the bridge is experiencing dynamic load.