Introduction: Trebuchet With Paint Sticks

Project Intro

In this instructable, I will be going over how to make a trebuchet mainly out of paint sticks. This project is aimed towards high school students but high school teachers can also use this instructable to plan a lesson

Learning objectives
Students will be able to comprehend and create a working trebuchet after going through this instructable.

Students will be able to apply their knowledge of making a trebuchet to modify and change the original design.

STELs:

Standards

  • Design in Technology & Engineering Education:

Making a trebuchet is an iterative process. You can follow my steps to get to the same conclusion as me, but you can also take it a step farther and modify different parts to see how it changes how the projectile is thrown. You could use a different object for the projectile, change the weight of the counterweight, change the pouch/carrier for the projectile, or even change the lever or frame sizes.

  • History of Technology

Trebuchets help define history and can be used to teach students about the history trebuchets were involved in and deepen their understanding of the past. Students could learn what technologies influenced and where influenced by the trebuchet. They can also review the positive and negative impacts that trebuchets created.

Practices

  • Creativity

Students can use different materials to make the trebuchet. They can modify and improve the original design to see if they can make the projectile go higher, farther, etc. By doing this, students will fail at times but they will be able to learn from the failure and use it to succeed.

  • Making and Doing

Students will follow the guide to make the trebuchet and then they will physically make it. If students choose to modify the design after completing it, they can plan out what they will do first and then act out their plan.

Contexts

  • Built Environment:

Structures are used by humans in everyday life and serve different purposes. Depending on the structure, different systems can be utilized to support it. For the trebuchet, the base provides stability for the structure when sending the projectile. The lever and axel allow movement in such a way that will launch the projectile.

  • Material Conversion and Processing

This context involves the physical creation of things. In this instructable, you will use paint sticks, wood, glue, rope, and more to create a trebuchet. Students could use this project to learn about how the materials used were made, like wood, glue, and rope.

Step 1: Materials and Supplies

You will need the following supplies

Washers ( I found these at my house so I had to measure them out myself )

  • 1 washer- (outer diameter is 1 inch, inner diameter is 7/16 inches) ($0.46)
  • 1 washer- (outer diameter is 10/16 inches, inner diameter is 4/16 inches) ($0.98)
  • 4 washers- (outer diameter is 8/16 inches, inner diameter is 4/16 inches) ($0.98)

The total cost of everything to make one trebuchet is $84 (without including the drill press and table saw). Including the table saw and drill press, the total is $318.98. While this is the price to make one, many materials can be used again to make more, like the duct tape, measuring tape, hole punch etc. The main things you would need to buy more of are the paint sticks, dowel rod, rope, counterweight container, and the weight for the counterweight.

Step 2: Measure, Mark, and Cut Your Paint Sticks

**Make sure to wear safety glasses when operating machinery.**

The frame will be made of a square base and 6 support beams that will be elevated (3 on either side) to support the axle.

For the following measurements, you will only need to measure and mark one piece. When you cut with the table saw or drill with the drill press, stack all the pieces that will need the same cut under the marked piece.

After gathering your materials, the first thing you will want to do is measure out your paint sticks. You will have 4 pieces to make up the bottom of the frame. The two width pieces will both be 9 inches long. The two length pieces will be 8 inches long. Once you have marked all your pieces it is time to cut them.

Next, you want to measure out the spots you will be drilling. For the two pieces that will be completely vertical, mark a spot 10 inches up on the stick. You will want to then mark where the middle of the stick is so measure the width (1 1/16 inches) and mark where the middle is (8.5/16 inches).

For the four angled pieces, you will want to measure a spot at 10.77 inches ( or 10 12.32/16 inches) along the ruler. Again, mark the middle of the width of the ruler. Making the two marks will give you a + sign. Using a 3/8 inch drill bit, drill the holes

Finally, you will want to mark your lever arm. You will be marking three holes on this piece. One for the axle, one for the counterweight, and one for the projectile. Mark a spot 0.75 inches (12/16) into the paint stick for both the counterweight and the projectile. Then starting from the projectile side measure out 9.5 inches for the axle hole. For all three holes, mark where the middle of the beam is to make sure the hole is centered. The projectile and counterweight hole will be drilled with a 1/4 inch drill bit and the axle hole will be drilled with a 3/8 inch drill bit.

Step 3: Final Cuts

The last cuts you will be doing are for the axle (wooden dowel rod) and the angled frame pieces.

For the axle piece, measure out 11 inches on the wooden dowel rod and mark it. Then cut it using the table saw.

The last cut you need to prepare will be on the angled pieces. When figuring out their placement, first place the vertical place directly in the middle of the 8 inch beam. (the vertical beam will be on one side of the horizontal beam and the two angled pieces will be on the other side)

*To make sure it is in the right spot, measure out 8.5/16 inches from the center (4 inch spot) of the paint stick. Make small marks to indicate where the edges of the vertical beam should go. Use a piece of duct tape to temporarily secure the paint stick.

Then line up the angled frame pieces. You can use the dowel rod to make sure the holes line up. To determine where the angled pieces will go and be cut, put the outermost edge at the end of the horizontal beam. Mark a line on the angled pieces that shows the part of the stick that is sticking past the horizontal beam. Mark which piece is directly touching the ground (G) and which piece is in the middle (M) of the ground and the vertical beam (again mark only the one set and plan to stack the other set underneath the marked pieces).

*This will make sure that the holes and pieces line up once cut if there were any slight errors while making the pieces earlier.

Before cutting the pieces, make sure you have both sets of angled beams, G and M, and that the holes line up.

Use the table saw to cut the beams and angle the miter gauge so the cut line lines up with the saw blade.

For my 2 G pieces, I had set my miter gauge to 70.5 degrees.

For my 2 M pieces, I had set my miter gauge to 78 degrees.

Step 4: Putting the Frame Together

It's now time to put the frame together. You will want to first make the two sides with the vertical and angled pieces, and then connect them with the width base pieces.

*Before gluing you may want to consider cutting a small piece of the dowel rod to make sure the hole lines up and to keep glue off the actual dowel rod you are using.

Gluing the sides with the vertical and angled pieces

  1. First, mark on the pieces where you will glue. You will see in the pictures for this step the "X"s I made.
  2. Now, glue the vertical beam to the horizontal beam. Use the previous marks you made in step 3 to help locate where the vertical beam will go. Make sure the bottom of the vertical beam is flush with the bottom of the horizontal beam. (wipe away any excess glue with a paper towel)
  3. Next, glue on the middle angled beam (3 spots in total: one on the horizontal beam and two on the vertical beam on both sides of the hole). (wipe away any excess glue, especially any in the hole)
  4. Next glue the ground angled beam (3 spots again). (wipe away any excess glue).
  5. Use a piece of the dowel rod to make sure the holes line up.
  6. Use a clamp or put weights (I used notebooks and a textbook) on top of the glued pieces (cover the frame with something to keep glue off of whatever it is you use). This will help make sure the pieces stay together and have a strong bond
  7. wait 30 minutes
  8. While waiting, you can repeat steps 1 through 7 to make the second side

    Step 5: Putting the Frame Together (part 2)

    Connecting the two sides

    We will now combine the two sides with the width pieces. The width pieces cover the length pieces (instead of going between them). Make sure that the length pieces are positioned so that the vertical pieces are facing outside of the box frame.

    1. First, put glue on the ends of the length pieces and press the width piece against them (make sure the bottoms are flush. (remove any excess glue)
    2. Cover the areas that have been glued with a paper towel and use items to apply pressure to push the pieces together (see above picture)
    3. Repeat on the other side.
    4. Wait 30 minutes.

    Step 6: Making the Counterweight

    For the counterweight, you first want to start by getting a container. I used a plastic Pillsbury container with a screw-on lid from the dollar store. You will want to use a ruler to find and mark the center of the lid (even though it already had a defined mark for the center). You will want to drill a hole with a drill press or a drill. I used a 3/16 inch drill bit for the eye hole (which was also 3/16 inches).

    I then put washers on (the first one is the one with an outer diameter of 1 inch and an inner diameter of 7/16 inches and the second one is the one with an outer diameter of 10/16 inches and an inner diameter of 4/16 inches) and screwed the nut on.

    I then connected the breeching snap to the eye hole. I then cut a piece of rope (14.5 inches) and fused the ends by burning them with a lighter. Then, while wearing work gloves, I pressed on the ends to make sure they were fused securely. I then tied a figure 8 on a bight (see pictures for how to do this). The loop this knot made was (1.5 inches). I pushed the knot through the counterweight hole I drilled on the lever arm.

    I filled the container with loose change that I had. It was much heavier than the projectile but I was unable to weigh it. I had a luggage scale but it would not read the weight when I tried weighing it (I am assuming it was because it was lighter than what the luggage scale could read).

    However, I was able to figure out the weight of the coins, based on the amount I had. A penny weighs 2.5g, a nickel weighs 5g, a dime weighs 2.268g, and a quarter weighs 5.67g. Multiplying these by the amount of each (listed in the material list) gives me 838.264g.

    After putting the weight in, I then screwed on the lid and clipped the breeching snap onto the loop.

    Step 7: Projectile Preparation

    First, pick a small object to be your projectile. I found a rock outside. I was unable to weigh it because all I have is a luggage scale and it would not read the weight of the rock. You could also use a marble or other objects as your projectile.

    Next, make the carrier for the projectile. Cut three 5.5 inch pieces of duct tape. Choose one piece and place it so the sticky side is up. Then place another piece on top of it so that it covers only half of the first piece. Press the two pieces together and then fold the second piece over the first one so that it sticks to the back of the first one. Finally, with the third piece, cover the remaining sticky portion of the first piece and position it so the excess can be wrapped around the backside of the first piece. Then measure out 2.5 inches on the pouch and cut it.

    Fold the pouch in half and from the corner (the one on the edge and not at where the crease is after folding it) mark a spot 4/16 inches in. Do this again on the perpendicular edge to make a cross. While the pouch is still folded, use a hole puncher to punch out holes where you marked (see the pictures above).

    I then added a stopper to the pouch with a scrap piece of wood (You can make it from a remaining piece of a paint stick that you cut earlier). It is 1 1/16 inches long and 6/16 inches high. Stick a skinny piece of duct tape to the back of the piece of wood. Then attach it to one of the long sides of the pouch. Then take another skinny piece of duct tape and attach it to the other side of the wood and the other side of the pouch (see the picture above to see the result).

    Step 8: Projectile Preparation (part 2)

    Measure out two pieces of rope that are at least 12 inches long (it can be longer if you want to give yourself more room to work with when tying the knots, you can cut any excess you have). Put one string through the hole from one side of the lever arm and the other rope through the other. Then tie a square knot to keep them from coming undone (see pictures above for how to tie a square knot).

    Next measure out two more pieces of rope that are at least 6 inches long. Tie one of the shorter pieces of rope to each of the longer pieces of rope with the overhand knot.

    Finally, you will attach all four loose string ends to the projectile carrier. Feed the strings through the holes of the carrier (one for each), put a washer on the rope (outer diameter is 8/16 inches, inner diameter is 4/16 inches) so that it is between the carrier and the knot, and tie an overhand knot. You want to do this so that the pouch is about 9.5 inches from the end of the lever if you hold it out straight. Make sure the knots on the different ropes are at the same points to make the system even.

    Step 9: Final Result

    Congratulations! You have successfully made a trebuchet! Go test it out! I have attached two videos above of the trebuchet in action as well as pictures of the final product.

    Step 10: (Optional) Modify the Trebuchet

    Now that you have made the trebuchet, you could consider modifying it. You could use a different counterweight or projectile carrier. You could use a different weight or change how the lever arm is divided. I have attached images of some different counterweight carriers I was considering as well as another type of projectile carrier. Try things out and see how they work! Have fun!

    Simple Machines Challenge

    Runner Up in the
    Simple Machines Challenge