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Building Catapults for the Central Florida Scout Show



I recently got asked to come up with project for Scout Day.  I had never heard of Scout day even though I was in the Cub Scouts and Boy Scouts.  So after a little googling I found that its a mix between a carnival and a Maker Faire.  After watching my son play angry birds I settled on miniature catapults

The first catapult mock up was clunky and was used to determine the arm length, positions of the rubber band holder, and the arm stop point.  Most of this was scrapped in the second prototype, but the locking mechanism and swivel base remain unchanged. These are the small circle in the upper right and the odd square with the [[  shapes inside.

Prototype 1 fully assembled

The next prototype involved cutting away everything not needed and give it smoother lines. Also added a handle so kids could rotate the catapult (yes they could shoot at each other, and did).

Prototype 2 assembled without basket.

After a few more tweaks to the design (7 revisions), I was satisfied that they were working and durable. Although I only planned for 5 in the final design, I cut parts for 6 so I would have a  “spare”.

The pieces fit together snug, and with a little wood glue they were nice and sturdy.

Here is the catapult assembled and painted with the Cub Scout Blue and Gold colors. The only purpose of the gold trim was to hide the assembly slots.  It also kept the axel for the armature in place.

Catapult arms did not survive their first test.  I glued the ‘basket’ to the arm after I had painted the individual parts so the first test shot sent the basket flying.  Two small wood screws fixed that issue.

Here is the base for holding the catapults fully assembled.

In this shot you can also see another assembly, this is for the target wall.  I figure a wall with holes in it would be simple and…boring.  Creating the door mechanism was a pretty straightforward.  I used the same .25 inch dowel for the door ‘hinge’ as I did for the axel in the catapults.

On to the target wall.  I was originally going to paint this as a castle and have  the odd shaped ‘holes’ knocked out of the brickwork.  After some cutting I decided to mix it up.

Add in the cut outs and the hinge mechanism with lots of wood glue.  I wasn’t sure how this would take the abuse, so I covered the contact points in glue.   It looked like a mess but held together no worries.

A quick test to measure the range of the catapults,  worked okay after doubling up the rubber bands.

Blue targets painted, but I had no string for the reset mechanism.   While I was out at Skycraft Pat and Tom put on an extra coat of paint. Thanks Guys!!

Here is the completed target wall ready to go.  With a pull to the strings hanging out the side, you could reset the top row or the bottom row.

Off to the Scout Show where Pack 42 assails the wall with bean bags.  This was the slowest period of the day, we usually had kids waiting in line. Not 15 minutes into it the first catapult broke.  The basket snapped off, but after plugging in the spare catapult everything ran for the remainder of the day with no issue.  Of course we did run through half a bag of rubber bands :(

Here you can see the magnets that were used to keep the panels in place.  There is a Magnet on the target wall and a small metal washer on the door.

Thanks goes out to the Familab members that offered suggestions, help, and testing.

All the files are uploaded to Thingiverse!!


Build and Enjoy,

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