How to Make a Rubber Band Powered Catapult
Rubber Bands Power This Wooden Model Catapult!
This little wooden catapult is a functional model powered by rubber bands. Though small, it is capable of flinging small objects with surprising force and distance.
Whether you use the catapult to storm a building-block castle in the living room or bring it into the office for launching candy over a cubicle wall, you can make a working catapult that older (and responsible) kids will enjoy and adults can appreciate.
This catapult is a fun and simple project to build. I selected several different types of contrasting hardwoods to make the catapult, including pieces of mahogany, cherry and oak. The different colors of hardwood add visual interest and appeal to this simple design, and a little Danish oil really makes the wood grain 'pop'. Best of all, it takes just a couple of hours to build the little catapult with a few pieces of wood that I found in the scrap bin.
How to Make a Rubber Band Catapult
Things You Need:
Cut scraps of hardwood into the following dimensions:
- Base (Part A): 8"L x 3 1/2"W
- Uprights (Part B): 4"L x 4"H (quantity of two needed)
- Catapult Arm (Part C): 6"L x 1 1/2"W
- Wheels are optional, either purchased or cut from stock using a 1 1/2 to 2" hole saw.
- 1/4" dowels, 3 1/2" long (quantity of two needed)
- 3" Heavy-duty Rubber Band
Use pieces 3/4" or thicker to make the uprights and wheels. The catapult shown uses oak for the base, mahogany for the uprights and wheels, and walnut for the arm.
Step 1: Some Assembly Required
- Layout a triangle on Part B to shape the upright. For strength, orient the top of the triangle along the grain of wood. Layout the center line of the triangle, from the top of the triangle straight down to the center of the base.
- Drill 1/4" holes along the centerline, positioning the first approximately 1 3/4" above the base and second approximately 3/4" down from the top. Sand to round over the top of the triangle and to smooth the edges. Repeat for the second upright, making sure to match the location of the holes to the first upright.
- Layout and draw the arm (part C). This is a simple spoon shape consisting of a bowl at one end. Use a compass to layout the 1 1/2" outer rim of the bowl, and then layout the 1" wide shaft of the arm. Cut out the arm and sand smooth. Use a 1" bit to drill out the cup.
- On the back of the arm drill a 1/4" hole 1 3/4" from the top of the bowl, approximately 1/2" deep. Be careful not to drill all of the way through the arm. Cut a small piece of dowel and glue it into the hole to form a pin. This little pin will hook on to the rubber band to supply the throwing power to the catapult.
- Drill a 5/16" hole through the arm to create the pivot point. Position the pivot point approximately 1 1/2" from the bottom of the arm.
Step 2: Make It Mobile
- If adding wheels, drill 1/4" holes through the base for the dowel axels. Position the uprights onto the base, and dry fit the catapult arm into position with dowels. The arm should move freely between the uprights. Mark the locations for the uprights, and then glue and clamp into place. Allow the glue to dry overnight.
- Cut dowels to length for the wheel axels, and glue the wheels to the dowels. Be careful not to allow any glue to squeeze out along the axels and into the base. The axels need to spin freely inside the base.
- To install the catapult arm, slide a dowel through the lower hole of the upright, through the lower hole in the arm, and then out through the lower hole in the second upright.
This rubber band catapult launches real projectiles which can cause serious injury if not used safely. This is not a toy for small children, and any child must be supervised appropriately. Use caution and common sense.
Step 3: Powering Up the Catapult
- Slide a second dowel through the top hole of the upright, and through the rubber band. Loop the rubber band around the back of the arm and over the pin.
- Pull the rubber band around to the other side of the arm and push the dowel through, catching the loop of the rubber band with the dowel before pushing it into the second upright.
- If done correctly, the arm will be pulled against the dowel by the force of the rubber band.
- Pull the arm back, load the cup with an appropriate payload, and let it fly!
BE CAREFUL! The catapult will launch a marble or similar object several feet, and can pose a danger if used improperly.
Rubber Band Catapult Plans
More Catapult Fun
Did You Know?
The catapult is an ancient weapon of warfare, primarily used as a siege weapon for surrounding castles in the Middle Ages. Catapults hurled missiles of rock and burning tar into and over fortress walls, causing massive damage to buildings and other structures. The incoming missiles also inflicted massive physiological damage to the inhabitants trapped to within the city walls.
- There are three types of catapults: the Ballista, the Mangonel and the Trebuchet.
- The Ballista is essentially a large crossbow, firing large spears and sharpened poles at the enemy.
- When think of a catapult, the shape and functionality of the Mangonel typically comes to mind. The Mangonel uses a long arm that is pulled back under tension, then quickly released, hurling stones and other objects at the castle or opposing army.
- The Trebuchet is the largest and most powerful of the catapults. It uses a counterweight to quickly propel a short arm that is attached by long ropes to a sling. The Trebuchet generates a tremendous amount of power as it whips around the slide, propelling the thrown objects with speed and distance.
- Catapults were the first biological weapons, hurling diseased corpses, body parts and dead animals at the enemy.
Da Vinci's Catapult
This short video shows the artistic work of Leonardo Di Vinci come to life as a small model catapult.
Pumpkin Chunkin Trebuchet
© 2011 Anthony Altorenna