Project A.F.F: a K'nex Ball Machine

About: Hello there! I'm Knex2thelimit. I build all sorts of things with K'nex, from practical items to ball machines. Sometimes, I've even made things that have never been seen before, such as a bird feeder or a mo...

_This was my entry for the 2015 K'nex Contest_

Hello fellow Instructables viewers!

I am proud to present to you, my third K'nex ball machine, Project A.F.F.

This is my most complex ball machine, and the first of its kind.

Not only is this a standard ball machine, but it also serves a practical use compared to other ball machines that only circulate balls. This machine actually feeds fish.

Yes, indeed, this is the world's first K'nex ball machine to actually feed fish! (If there is another, please let me know).

Currently, this only uses a one-time feeding mechanism. This is meant for people who are, say, going on a trip for a day, but still need to feed their fish. All you have to do is connect the motor to a timer, set the time of feeding and Voilà! the machine takes care of the rest.

It's a simple mechanism: As the ball falls through a free-fall, it pushes out two clickers. The bottom one then pushes a tray over that holds the food, thus releasing the food into the tank below. The tray then tips back over, due to the counter weight. Watch the video to see this in action.

In order to hold the tank, I also created a sturdy table that can easily hold the tank while it's filled with rocks, water, and fish (of course). The table also includes a little theming, and is the support structure for the paths.

Oh, did I forget to mention that there are two paths? Yes, not only does this machine feed fish, but it also contains two paths for the ball to travel through once it has fed the fish. You can run this as a regular ball machine, without feeding!

So, why the name Project A.F.F? Well, "A.F.F" stands for:




Pretty simple, huh?

Here is some more information:

Build time: 5/3/15 - 5/25/15

Height: 3.8 feet (1.6 meters)

Length: 1.6 feet (0.5 meters)

Width: 2.6 feet (0.8 meters)

Number of lifts: 1 (Vertical Chainsaw Lift)

Number of paths: 2

A large, sturdy table it also included to hold the tank.

Special thanks to: Knextreme, for the main element in path 1 and the used design of the Vertical Chainsaw Lift.

Project A.F.F was selected as a finalist in the 2015 K'nex Contest! Thanks everyone!

Thanks for reading, watching the video, and checking out my Instructable! I hope you enjoyed this project; I know that I'm proud of it. See you all next time!


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    18 Discussions


    4 years ago

    Good luck and look forward for your íntruction to be posted!

    1 reply

    Thanks for commenting! This build won a runner up prize in the contest. Unfortunately, there will not be instructions for A.F.F. I have already taken it down in order to start something new, plus this is a large and complicated build that uses many pieces. Sorry about that!


    4 years ago on Introduction

    What a coincidence! I happened to think of the same element you used on path 1 at the beginning!! Haha! :P

    2 replies

    Reply 4 years ago on Introduction

    Wait, just to use? Or is it some new element I didn't know about? Either way, haha.

    Did you like the overall machine/idea for the machine?


    Reply 4 years ago on Introduction

    I had it built and I haven't even put it on our machine! I got it to work but I changed it later to something else that is similar. It may be in our next machine! Yes it's ingenious! Feeding fish! I think you will do well in the contest.

    I will vote but honestly I don't think it will make any difference now that sandro released that beast of a machine...He will win for sure.. That thing is just godly. :p

    True! My jaw dropped when I saw it!

    Why hasn't this been accepted yet... Huh. The two entries after me have been accepted... As in submitted after mine. Odd.