Intro: Simple Tension Catapult Tutorial
This is our final project for the 2014 Biomechanics Field Museum program. We were told to design a catapult using a software called Sketch-Up in both 2D and 3D which would later be processed through a CNC Machine. From there on we took it into our hands and built :)
Enjoy our simple tutorial!
For this workshop;
- 4'x8'x3/4" Plywood (2 Catapults/Sheets)
- Sketch Up Architecture Program
- Illustrator (Optional to clean up your Sketch Up BluePrint)
- String (Parachord)
- Wood Glue
- Plastic Cups
- Elastic/ Bungee Cord
Step 1: Using Sketch Up!
- Start up by opening the program Sketch Up.
- If you do not already know how to use the program, make sure to get the hang of it and mess around for a while before starting your catapult.
- You want to begin by making a 4'x4'x3/4'' square, this will be your work area.
- Make sure that as you build your 3D model, to make a flat copy as well (this will be your 2D model)
- Once you're done constructing make sure to export your flattened 2D model as a pdf file. (We had exported it as a .dxf but later found out that lead to complications with the other program.)
Step 2: CNC Time!
When you open up your file in V-carve
If it is messy;
- You will have to remove extra geometry and that can be done by using Illustrator.
- Once it is cleared and ready to go, you may start to run your CNC machine, we used Shop-Bot.
- After the pieces have been cut out you can pop them out.
Step 3: Time to Assemble!
- Once you've popped out all of your individual pieces, you're going to want to start to sand the edges to get rid of any rough parts. *WATCH OUT FOR SPLINTERS*
- Now you want to start to glue your pieces together.
- Following the glue make sure you put screws to better support your catapult.
- After you've finished constructing your catapult, you will need to take a string that is twice the width of your catapult and string it through the holes on the side of the catapult walls and through your catapult arm.
- Pull the string on to rods and twist them until you have the wanted tension built.
- If you want to give your arm more support you can add a bungee cord also.
Step 4: FInished!
This was our finished result.
We enjoyed creating this very much and we hope that you enjoy making your own catapult :)