Popsicle Stick Bridge

The goal of this project was to build a bridge using only popsicle sticks and glue that could span 32". Guides for each joint were designed in Fusion 360 and 3D printed out of PLA to make building the trusses much quicker. In total, four corner guides and ten joint guides allowed for not needing to measure any of the member angles. The guides were designed to be able to be universal by fitting any joint, firmly hold at least five popsicle sticks on top of each other, and not stick to the popsicle sticks after glue was added.

I am currently a student at the University of Wisconsin - Platteville pursing a Bachelor's degree in Civil Engineering. This project took a lot of time and effort, but I was very happy with the end result. Feel free to follow the guide below and make your own!

Needed supplies are as listed:

1. PLA filament
2. 3D Printer
3. Popsicle Sticks
4. Glue (super glue, construction glue, and/or hot glue)
5. Toothpicks
6. Scissors
7. Ruler

Popsicle sticks were measured using calipers to determine the width the guides needed to be. A small squared test U was printed with this width to make sure the dimensions allowed a popsicle stick to fit with some room. Truss member angles and the width dimension were then used to create guides for every connection. The joint guides were made specifically to be able to work with any of the joint connections regardless of if there was a vertical or diagonal missing. The side supports also had to be designed to hold at least five stacked popsicle sticks and have cut outs so that the glue would be less likely to stick to the them. All design work was done in Fusion 360.

The needed .stl files for this project are as follows:

After downloading the above stl files, they will need to be sliced so that the 3D printer is able to print the model. Ultimaker Cura was used in this project but any slicing software will do. Guides were sliced with the following properties but can be adjusted as needed:

• 0.6 mm Nozzle
• 0.2 mm Layer Height
• 2 Walls
• 45% Grid Infill
• 220 °C Nozzle Temperature
• 50 °C Build Plate Temperature
• 40 mm/s

To have a guide for every connection, you will need to print:

• 2 Bottom Corner Guides
• Note: You need to flip the model in Cura for one of them
• 2 Top Corner Guides
• Note: You need to flip the model in Cura for one of them
• 10 Joint Guides

1. Start by building the top and bottom chord members (8 Total)
2. The guides will help determine the lengths using a ruler
3. Cut and glue popsicle sticks on top of each other to the necessary lengths
4. It is recommended to use heavy duty scissors to cut the sticks and use toothpicks to help evenly spread the glue.
5. Make members as one continuous piece that is between two to five popsicle sticks thick
6. Build the webs (10 Verticals & 12 Diagonals Total)
7. Measure length between the top and bottom chords
8. Use the same method as described above
9. It is recommended to give all the glued pieces time to dry before building the trusses
10. Insert the top and bottom chords into the 3D printed corner guides and glue together
11. It is recommended to use super glue or another fast setting glue as these pieces need to hold the webs in place
12. After the glue in the corners set, glue webs in between the top and bottom chords using the joint guides to help determine the correct positions.
13. Carefully slide guide off all connections and glue popsicle stick gusset plates to sides of truss
14. These help hold the webs in place
15. This can either be done by cutting pieces to the correct size or pre-making plates and gluing them on
16. If you plan to test your bridge, large plates will help your truss hold more load
17. Repeat steps 1-6 to make another truss
18. Once both trusses are made, add lateral bracing between trusses to make the bridge the chosen width
19. Add diagonal bracing for more stability if desired
20. If you plan to test your bridge it is highly recommended to make the bracing two to three popsicles thick as well as having both lateral and diagonal bracing. This is because these bridges like to buckle under load.
21. After the trusses are built and connected with bracing, you have a completed popsicle stick bridge.

For this project, a 32" long x 5" wide x 8" tall bridge was constructed. All members were four popsicle sticks thick and gusset plates were one popsicle stick thick. These dimensions can be copied exactly or scaled down/up using the 3D printed connection guides. Have fun building your own!