Introduction: Cardboard Trebuchet
Welcome to our Instructable! We will be creating a Cardboard Trebuchet!
Please visit our schools engineering website www.sphsengineering.com
This was done as a engineering class project, and we had a set of rules to go by.
1. The trebuchet had to be made entirely of cardboard. For the parts that allow movement, PVC piping, string, and aluminum foil were allowed.
2. The trebuchet had to be waterproof! For this, we were allowed to do this by any means necessary, without inhibiting the function of the trebuchet.
3. The trebuchet must fit within a box with the dimensions 18in x 18in x 18in
4. The minimum distance the trebuchet must throw to is 30ft.
***AN IMPORTANT SAFETY NOTE***
While working with any tools, safety is of the utmost importance. That is why, while working on this project and any other, you must wear eye protection. You must also be sure that you keep long hair tied back and keep things off of around your neck.
Following these basic safety procedures will ensure a safe working environment while working on this project.
Step 1: Gathering the Materials and Tools
-Cardboard (35 sq ft)
-PVC Piping. 15 inches (40 cm) long with a 7/8-inch outer diameter and 5/8-inch inner diameter.
-PVC Piping. 15 inches (40 cm) long with a 1-inch outer diameter and a 7/8-inch inner diameter.
-Two tubes of Caulk. Recommended latex acrylic with silicon.
-Stiff yet flexible single strand copper wire. 3 inches (8 cm) should be difficult to bend with fingers.
-String. 2 yards (2 meters)
-Aluminum Foil, Aluminum Tape, or equivalent.
-15 Hot glue sticks.
-2 to 2.5 lbs (1 kilogram) of miscellaneous nuts and bolts for weight (or equivalent).
Step 2: SAFETY FIRST
For safety reasons please follow all these tips.
When working with tools wear goggles.
When painting wear a mask and goggles.
When using a hand saw wear gloves.
When using power tools make sure your surroundings are clear and you have no lose clothing, jewelry or hair.
When using the Trebuchet never fire at people, stand clear And wear goggles.
Also use common sense and be careful.
Step 3: Laminate Cardboard
Step 4: Cutting the Stock
Step 5: Make Notches in the Base
Step 6: Drill Holes
Step 7: Cut the PVC Pipes
Step 8: Gluing the PVC Pipes in Place
Step 9: Groove the Base
Step 10: Connect the Sides to the Base
Take the sides of the trebuchet and place each one inside each slot made into the base. It is important to ensure that each angle is the same on the sides. Steep next to steep, shallow next to shallow. When you do this, you want to thoroughly glue the arms to the base.
Step 11: Making the Weight Basket
-Bend the piece into an arc so that the edges line up with the outer edges of the sides that make up the basket. See pictures for reference.
-Using hot glue, glue this all together into place. While gluing, be careful of alignment. Our first model was a little crooked.
Step 12: Apply the Caulk
Step 13: Waterproof With Glue
Step 14: Extra Waterproofing Through Paint
Using spray paint, paint the arm and weight basket thoroughly. (Apply several coats. Must be completely covered with thick layers of paint.)
Step 15: Decoration Time!
Once the base has dried, apply a decorative coat of paint. The color is up to you.
Step 16: Main Assembly
Once everything is dry, assemble the trebuchet as shown in the provided images.
To create the hook in the top of the swing arm, put a small loop 1" from the end of the copper wire. Insert the longer end into the small end of the swing arm and glue it in place.
Step 17: Projectile Basket
Cut 2 pieces of 32" string.
Make a 2" square of aluminum foil or aluminum tape.
Secure one end of string to each of the four corners of the basket, leaving one inch of string overlapping into the basket.
See pictures for clarification.
Step 18: Firing and Fine Tuning
Hook one loop of the string on the basket to the loop in the copper wire in the swing arm. Loop the other end around the piece of copper loosely. Pull down on the projectile basket with a ball inside and pull through the center of the trebuchet (between the sides) as far as it can go. When ready to fire, let go of the projectile basket.
With the proper amount of weight in the basket, the trebuchet should throw the ball around 30ft. If the path of the ball falls too short, while standing behind the trebuchet (opposite side from where the ball flies), bend the copper wire back towards you if it's too late in releasing, and bend it forward away from you if its too early in releasing.
Also, the distance the ball goes largely depends on the amount of weight that is in the weight basket. More weight = further distance.
Step 19: Appendix
Solid works documents for extra reference,
PDF of all instructions,
And a zip file that contains everything needed including cutting PDFs