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Hi There, I've been toying around with wooden peg ideas using elastic bands to give them grip when it dawned on me. The same principle could be used to create a really simple and really small catapult.

So here it is, a step by step guide to make the worlds simplest catapult. Ive used 3D models drawn in Google Sketchup for each step as I thought it might help you guys understand each step a little better.

If you have trouble reading any of the dimensions in the pictures try downloading the instructable as they are difficult to read on mobile devices but I made sure they look fine in normal PC/Mac browsers :)

UPDATE: I have recently modified my way of working with this project. I have started holding two thinner pieces of wood together with masking tape to make the block which saves the slicing in half step. Hope this helps

What you will need:
A scrap piece of wood
1x 25mm of dowel (approx 9mm in diameter)
1x elastic band
 
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Step 1: Marking out

Picture of Marking out

Although the actual size of the catapult is not important the proportions kind of are, so for the prototype I made I used simple sizes to illustrate the proportions as best I could.

Start of with a block of wood and mark it out as shown. Please note the diagonal line will only only shown on this step and on the step it is required for in order to save confusion.

Step 2: Drilling the holes

Picture of Drilling the holes
When you have fully marked out your wood. You need to drill it at the two crosses. The top hole needs to be around 16mm in diameter and no more than about 6mm deep. This will act as the catapults ammo cradle (sorry I don't actually know what it is called but you get the idea). Make sure this hole does not pass half way through the wood. You will see why later on.

The hole on the side goes all of the way through to the other side and should be the same size as the dowel you will be using. Ensure the dowel is a fair size so that the mechanism works easily (as you can see from the size of the hole it is roughly half of the thickness of the piece of wood so if you are tweaking sizes bear that in mind).

Step 3: Cutting the slots

Picture of Cutting the slots
Using a small needle file, dremel, band saw etc (whatever you have to hand and feel comfortable with) cut two slots in the wood as shown.

Step 4: Forming the body

Picture of Forming the body
When you have your holes drilled and slots cut simply cut the body down the center as shown again using whatever tool you feel comfortable with (tenon saw, band saw, dremel etc).

Step 5: Add the firing angle

Picture of Add the firing angle

As you can see the diagonal line indicates the area that needs to be removed in order for the catapult to work. This section can be cut away, filed or sanded off. I used a disc sander to do this.

Step 6: Fitting the hinge mechanism

Picture of Fitting the hinge mechanism
Probably the simplest mechanism but it works great. Simply glue your dowel into the channel of the bottom piece of your body as shown.

Step 7: Almost there

When the glue has dried pop the two parts back together and attach the elastic band. The tighter you make the band the stronger your catapult will be. Make sure the band goes into the groves.

I also shaped the top section of the catapult before attaching the band to make it look more realistic, however this is just an aesthetic choice and does not help the function of the catapult in any way.

This is simply the basic concept. If you plan ahead you could even add wheels and other decorations to it but I didn't want to insult your intelligence by showing you how to add embellishments.

Hope you enjoyed this instructable. Take care :)
Dom Toretto2 months ago
Can I buy one
Anyone know the range of this???
Andsetinn1 year ago
Really nice. Simple and clean design. Easy to make. A really good example of an instructable.
Brilliant ! - Some of us never grow up... I had to make one but due to having fingers like sausages I had to adapt it like so...
006.jpg
Hehe. My dad suffers from the same problem. He couldn't use it either. Looks great!
coppertop82 years ago
Genius. Hopen for a snow day tomorrow so I can make 1. I foresee trouble in the classroom : ) ...
nattyclem2 years ago
Good design and I love the simplicity of it.
As I still go to school and do DT, I would love the teacher to get us to do something like this.
jonnyd552 years ago
If you teach electronics it would be super cool to mod this idea to be held open with electro magnet or solenoid latch connected to a pic chip circuit which triggers the catapult with a given input, push button, LDR, pressure sensor etc....?
THIS IS LIKE AWESOME!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!I
cool
kyao2 years ago
genuis
sashadistan2 years ago
This is really awesome. I have just qualified as an NQT DT teacher is resistant materials this would make a great focused practical task, along the idea of letting year 10's make weapons is slightly worrying. brilliant project, thanks.
MrF_DT_teacher (author)  sashadistan2 years ago
Well done!!!! I teach resistant materials, electronics and graphics. It's a great idea to have lots of little things like this as extension activities. As a focused practical I don't think there is enough in it unless you turn it into a mini design and make activity. They could make this little catapult then have to design some kind of desktop game for it, like a series of holes worth different points and lights flash when the ball passes through each one :) Keep me posted on anything you come up with related to this instructable or not. Thanks :)
l0b02 years ago
Neat! Which software did you use for the design? It looks very print friendly.
MrF_DT_teacher (author)  l0b02 years ago
Google sketchup. Love it and it's free to download
zmike12 years ago
i bet you could modify i clothes pin?
MrF_DT_teacher (author)  zmike12 years ago
Defiantly. I think there are some instructables out there which do that. I wanted to make a bespoke catapult that looked like an actual catapult as opposed to something modified :) thanks for the post
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