Marble Cannon

By: Maddy McCort and Caleb Hooper

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Step 1: Gather Materials

You will need:

  • 3 planks of wood
  • PVC pipe
  • 2 large springs
  • A PVC coupler
  • Wire
  • 4 screws
  • Dowel rod

For construction you'll need a drill.

Step 2: Cut the PVC Pipe

You will need to cut 2 slits on opposite sides of the PVC pipe. The slits should go from the end to about halfway up the pipe. The slits have to be big enough to fit dowel rods.

Step 3: Make the Ram

For the ram, you will use a larger dowel rod that fits snug inside the PVC pipe. Near the end of the dowel rod, you'll drill a hole to fit the smaller dowel rod. This will serve as the handle and will fit along the slits in the pipe. Then place the ram into the PVC pipe.

Step 4: Glue on the Cap

Once the ram is inside the PVC pipe, glue a cap on the end so the ram doesn't slide out.

Step 5: Put Screws on the Handles

Put screws on the handles of the ram, and make it so the screws face out towards you. The screws have to be the right size, because the springs will be hooked onto them.

Step 6: Set Up the Coupler and Placing Springs

Drill 2 screws on opposite sides of the coupler. These should be the same size screws as in the last step. The screws should be drilled exactly in the middle of the coupler so they don't penetrate the inside of the pipe. Then place the finished coupler onto the PVC pipe, opposite of the ram.

Then get the 2 springs and attach them to the coupler screws and corresponding ram handle screws.

Step 7: Mark the Pipe

You will then need to mark percentages on the pipe to accurately tell how far the ram is pulled back. For example, pulling the ram halfway back would be 50%.

Step 8: Build the Base

Place 2 longer pieces of wood perpendicular of each other, one flat on the ground and the other standing straight on top of it. Get a smaller standing piece and place it up against the long-standing piece against the base. Drill the 2 standing pieces to each other. Drill 3 holes at the top of the flat piece, then attach 2 dowel rods to the longer standing piece and 1 dowel rod to the smaller standing piece. This is so the pieces can be easily attached and unattached. The video will show how the pieces are placed together.

The shorter standing piece will serve as a resting block for the pipe. So you'll need to make a "v" design at the top of the piece so the pipe can safely rest on it.

Step 9: Attach a Block to the End of the Pipe

You will need to get a small block of wood will attach to the end cap of the pipe. You will need to drill a screw into one side of the block. Then get some wire and weave it around the screw and through the wood. Then weave it into the cap of the pipe. Make it tight enough so it won't come loose and the wood stays attached to the pipe.

Step 10: Attach the Block to the Base.

Put 2 dowel rods onto the bottom of the wood piece you just attached. Then drill a number of holes on the base, so the dowel rods can fit snug into each of them. These pairs of holes will serve as increments to adjust the angle of the pipe. The piece of wood should be able to easily move between each pair of holes.

Step 11: Calculate Its Performance

Based on our 3 best shots we calculated that,

  • In trial 1, when aiming for 2.5 m, the marble traveled 2.35 m with a launch height of 0.33 m and an angle of 38 degrees. It was in the air for 0.66 s and traveled with a velocity of 7.12 m/s.
  • In trial 2, when aiming for 2.5 m, the marble traveled 2.4 m with a launch height of 0.33 m and an angle of 38 degrees. It was in the air for 0.67 s and traveled with a velocity of 7.16 m/s.
  • In trial 4, when aiming for 3.5 m, the marble traveled 3.6 m with a launch height of 0.26 m and an angle of 28 degrees. It was in the air for 0.66 s and traveled with a velocity of 10.9 m/s.

The video demonstrates how the cannon is shot.

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