Instructables
Picture of Make a desktop trebuchet
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A trebuchet is a gravity powered catapult. This one is my own design. It's made to be laser cut (or scroll sawed) out of 1/8th MDF or plywood.

This kit is an intermediate difficulty. There are lots of parts to glue and some need to be lined up by hand. It takes me about 30 minutes to go from a pile of parts to a fully working trebuchet.

Here it is firing some little wooden "bullets".

Step 1: Gather Materials

Picture of Gather Materials
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You will need:
  • One set of wooden parts. Use attached PDF.
  • One cloth sling. Use attached Basket.pdf for a pattern.
  • Some ballast for the counter weight. (nuts, small bolts, BB's, lead shot, etc)
  • Wood glue
  • strong thread or thin string
  • A long twist tie, some masking tape, small wood clamps or other way of securing some of the parts while the glue dries.
  • Some 400 grit sandpaper (optional)
For the wood parts you can use the attached files to create your own or send them off to a laser cutter to make them. It should work fine in 1/8th MDF, Baltic Birch and probably acrylic or lexan (use the appropriate glue of course). You can open the .svg files in Inkscape.

Feel free to make as many kits for personal use as you want. (It's not alright to sell kits without my permission, OK?) The basket on the counterweight is a "living hinge" design. It bends where the laser scored it. There are 2 on the template since it's the most likely part to break during assembly. It's probably not possible to do on a scroll saw. You will need to modify the design somewhat.

Step 2: Hints and tricks

Picture of Hints and tricks
  • Use full strength wood glue.
  • Use glue sparingly. It doesn't take much to solidly stick this model together.
  • Wipe up excess glue right away. Some parts might not fit if you let glue dry in random places.
  • Be gentle with the small parts. They can break during assembly.
 
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Very fun! You should enter this into the Holiday Gifts Contest!
Who doesn't love a good mini catapult