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Author Topic: Catapult project  (Read 3269 times)

Simply7

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Catapult project
« on: April 29, 2013, 10:00:15 PM »
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!!

http://www.thingiverse.com/thing:81846?

Build and Enjoy,
Simply7
« Last Edit: April 29, 2013, 10:22:01 PM by Simply7 »

digitalman2112

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Re: Catapult project
« Reply #1 on: April 29, 2013, 10:20:23 PM »
Awesome!

I usually attend with my boys, but didn't go this year - sorry I missed it!!

P47

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Re: Catapult project
« Reply #2 on: April 29, 2013, 11:11:45 PM »
Rick, AWESOME WORK!!!

digitalman2112

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Re: Catapult project
« Reply #3 on: April 30, 2013, 07:11:44 AM »
Do you mind if I turn this into a blog post on familab.org?

Simply7

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Re: Catapult project
« Reply #4 on: April 30, 2013, 07:44:30 AM »
Go right ahead. I was going to but haven't had a chance to check out your instructions.

digitalman2112

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Re: Catapult project
« Reply #5 on: April 30, 2013, 07:55:47 AM »
Go right ahead. I was going to but haven't had a chance to check out your instructions.

First step: Create an account at familab.org/blog - then I'll give you editor permissions

In the interim, I'll do the cut & paste on this one, then set you as the author once you have an account.

digitalman2112

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Re: Catapult project
« Reply #6 on: April 30, 2013, 08:05:26 AM »
Blog post created (you made it very easy by posting it all here!):

Steps - Copy & paste from forum, then set all the images to 70% to fit the column width, then created featured image (quick photoshop of a 620x300 from your images), uploaded & set it.



Hybridsix

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Re: Catapult project
« Reply #7 on: April 30, 2013, 09:16:53 AM »
Rick - Be sure to wear a hard hat when using catapults. :)

Simply7

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Re: Catapult project
« Reply #8 on: April 30, 2013, 09:19:16 AM »
Good advice. Some kids launched them over the wall and I got hit a few times while retrieving bean bags. :-\

Ronster

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Re: Catapult project
« Reply #9 on: April 30, 2013, 04:34:52 PM »
Simply awesome Rick! Just hide them before dinnertime at your house! Or maybe the kids can use them to launch marsh-pillows. :D

AtomicProf

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Re: Catapult project
« Reply #10 on: October 23, 2013, 06:32:46 PM »
I failed to give the "Awesome" comment -- So I am doing it now.


Awesome!
There is Quality in the Details
That is All

Ronster

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Re: Catapult project
« Reply #11 on: November 06, 2014, 03:20:53 PM »

Simply7

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Re: Catapult project
« Reply #12 on: November 06, 2014, 08:11:08 PM »
It wouldn't be that hard to modify this to a small kit.  All I need is time....