I have a few nieces and nephews coming around lately and they are always going into my scrap bin to build stuff and then knock it down over-and-over again. I decided to make them a small set of building blocks, complete with two battling catapults. It has 46 blocks in total, made from 3/4" maple stock. The catapults are made from Maple along with a stick of Cherry for their throwing arm. The ball cup and throwing arm were made on the lathe, the rest was made on the table saw along with a miter sled.
Download the 3D model here
Step 1: Tools and Materials
- Table-saw with a miter sled
- Drill press
- Cordless drill and driver
- Disk/Belt sander
- Orbital sander
- 3/4" drywall screws
- Wood glue
- 2 small eye screws
- Marbles or some type of ammo
- 2 different color ribbons and 4 toothpics
- spray adhesive
Step 2: Start the Catapults
I ripped some 3/4" Maple stock to 1" wide. Then switched over to the cross-cut blade and used the miter sled along with stop blocks to keep everything uniform and accurate.
The sides of the catapult are 8" long the front and back are around 4" long. So cut 4 pieces 4"X1" and 4 pieces 8"X1".
I also cut 2 crossbeams (Throwing arm stop blocks) at the same time.
After all the stock is cut sand each piece individually.
Step 3: Glue the Catapults
We need to drill the hole for the arm pivot axle. This needs to be as accurate and uniform as possible so I clamped all four sides together and marked for the hole. I took that to the drill press and using a 3/16" brad point drilled through all four pieces at the same time. You might need to do two pieces at a time depending on your drill bit length.
Once the holes are drilled give the pieces another quick sanding. Next glue and clamp them together and let them sit to dry.
Step 4: Make Some Spacers
To keep the throwing arm from floating around on the pivot axle I used 2 spacers on each catapult. I drilled the holes the same way as the sides. then cross-cut them in half. Now slide the axle bolt into the hole and add the spacers in the middle. Push the bolt all the way through and then add some glue to the spacers. Using spring clamps, hold them in place and let them dry 1 hour should be plenty.
Step 5: Make the Throwing Arm and Ball Cups
I used 3/4"X5/8"X6 1/2" cherry stock for the throwing arm. I mounted the piece between centers and marked two lines to give me a visual stopping point. The ball cup side is 2" and the pivot side is 5/8".
Round everything in-between the lines. Then sand to 220 grit. Do this 2 times.
Then I took the arm to the disk sander and removed the sharp corners on the 3/4" flat sides
Now I used 1 1/2" X 1 1/2" X 3/4" stock for the cups. I mounted them in the chuck and used a small fingernail gouge to dish it out in the middle then sanded the inside of the cup. I then took the ball cups to the band saw and removed the bulk of the material needed to shape it round. Next, using the disk sander, I rounded everything to shape and then did a final finish sand for them.
Step 6: Add the Arm Stopping Block
Now we need to add a stopping block to the frame of the catapult. I used a single 3/4"X34" material and cut it to length for each catapult. I also sanded and beveled the top edges on each one.
The stopping point is a bit important. If you mount it wrong it will simply throw the ball straight up, or straight into the ground. I basically raised the throwing arm until it was perfectly vertical and placed the stopping block on the frame. Now let the arm down and slide the block back (toward the back of the catapult) about 1/16" of an inch. The further back you go with it the higher the arc of the ball upon release. A perfectly vertical stopping point throws the ball straight at the target.
while you are holding the stopping block in place drill pilot holes and then add a drop of glue to each point and screw it down.
These are pretty big catapults and my first few throws with marbles throws it about 10-12". This changes with the rubber band size and tension.
Step 7: Cut the Blocks
Time to make the blocks. I grabbed the rest of the maple stock I had left over from the catapult frames and sanded both sides of the boards with an orbital sander. I then ripped some more maple 1" wide and then, using the miter sled and stop block, I cut all 46 blocks to size. Then a quick finish sand.
Step 8: Make the Wheels for the Catapults
I mounted some stock between centers and finish cut it to about 1 1/2" in diameter. I then mounted it in my chuck.
Next finish sand about 5" of the length. Each wheel is 1/4" thick. I marked each wheel and did a quick cut to define the wheels.
Then using the 3/16" brad point bit and my tail-stock Jacobs chuck, I drilled the center for the wheel axles. Then I used my parting tool to part off each wheel one at a time. The wheels are purely aesthetic, they do not turn.
To mount them, I placed the catapult on a small scrap of 1/4" MDF to raise it. then I placed each wheel individually and drilled a very shallow pilot hole. Then put a drop of glue on the hole and put the wheel in place I screwed into final position with 3/4" dry-wall screws.
Step 9: Add the Trigger Release Mechanism
I'm sure there are many different and better ways to add the release mechanism. I simply screwed an eye screw into the end of the throwing arm on the bottom, then held it in position and drilled into the back of the catapult through the eye screw opening. then using a coat hanger or some thick gauge wire to hold it in the "cocked position". Then when you are ready to fire simply pull wire.
Step 10: We Need Some Flags.
We need to make some flags so I grabbed some toothpicks and raided the fiances sewing room for some ribbon. Then I placed the strips of ribbon flat and sprayed them with some contact adhesive. After about 30-60 seconds I placed a toothpick in the middle and folded the ribbon around it. Then using some sharp scissors or a razor blade I cut them to final shape.
I drilled a small hole in each catapult to hold a flag, and I also went to my scrap bin and grabbed some "failed" chess pieces I had in there and drilled a hole in the tops of them to act as flag carriers. Knock those down to win!
Step 11: Prepare for Battle
We need to add rubber bands to the catapults. I placed a 3/4" screw in the front of each and wrapped a rubber band around the top of the throwing arm and stretched it to the screw. The rubber band will determine how hard/long the ammo will be thrown, so keep some various sized bands for it.
Step 12: How to Play
This should be pretty much self explanatory. Before setting up, test the various ammo and rubber bands to get the distance dialed in. You can play the game many ways. You can set up facing each other. Or you can set up each wall and flag carrier close to each other and take turns shooting. I also think it may be a good idea to offer a flag carrier move Instead of firing on each turn. (If they are getting close to hitting your flag carrier you are allowed to move it 6" in any direction, but you cannot fire your catapult if you move your flag. You could also offer a re-build move. Allow the re-building of a certain number of blocks per turn as well. You can mix and match these options for a more interesting game.
Update: My daughter was kind enough to shoot a video of it shooting.
You can view it here
Second Prize in the
Weekend Projects Contest