Knex Circle Ball Machine

Introduction: Knex Circle Ball Machine

About: K'nex is my thing!
Well, here is a small ball machine, with a twist - No lift!

What?! No lift? How the heck does that work?

Well, it works like this. The track is a smooth flat circle, sitting on the base. The base has four "Arms" that stick out, and at the end of each one is a mechanism that makes a rod go up and down. These uppy-downy rods connect to the circular track and cause it to ossilate in such a way that the ball rolls around in a circle. Watch the video to make sense of it all.

Hope you like it!

Step 1: Piece List

Here's the piece list.

Green - 180
White - 64
Blue - 162
Yellow - 80
Red - 12

Dark Grey - 4
Light Grey - 16
Red - 40
Green - 8
Yellow - 144
White - 12
Orange - 9
Purple - 137
Blue - 20

Tan Clip - 10
Silver Spacer - 72
Blue Spacer - 38
Hinges - 4
Ball Socket - 1
Ball Joint - 1
Red Gear - 4
Yellow Gear (large) - 2
Blue Gear (tiny) - 1
One motor

Got those? Lets get cracking.

Step 2: Track

This is the track. Whoopee!

1: Make the... track. It has 48 Yellow connectors on the inside and 48 on the outside. The inner track is solid, but the outside is not connected. Its made of yellows + Green rods. See the following two photos to see what I mean.
2: ---
3: ---
4: Make this
5: Make four of these.
6: Make four of these too
7: Put the first four on like so
8: And the other four on like so
9: Put the track in like so. Its connected to the frame every 6th piece.
10: Close up of what the connections look like.


Step 3: Base Arms

These are the arms that go out from the base. Make them. NOW!

1: Make these two bits
2: Put it together
3: Make these parts
4: Make this. Be sure you get all the spacers in the right spots
5: Close up of one end
6: Close up of the other end
7: Build this
8: Make this too
9: Put thems together
10: Add that axle thing. Presto!
11: Close up of the end
12: Put that one bit on top
13: Add the yellow rod/hinge connection
14: Close up
15: Add on the rest of the frame like so
16: Make four! Leave out one yellow rod on top of one of them. See note.

Three cheers for you.

Step 4: Base Center

This is the little bit where all the gear awesomeness happens.

1: Make these these three bits and get the spacers ready
2: Put the geared rod through the motor hole, and the other two as seen. Put spacers on.
3: Other side
4: Make this guy
5: Another side
6: And another view
7: Make four! (ouch!)
8: Build this
9: Make This gear assembley from this and the next two photos
10: ---
11: ---
12: Make this
13: Build these four corners
14: Build these three
15: Build this

No, this is not the last step. Keep going.

Step 5: Assembley

This is the little bit where all the gear awesomeness happens.

1: Put one of the corner pieces on it
2: Add one of the other pieces and put on another corner
3: Same again...
4: And once more
5: Add that center bit
6: Add in a gear bit into all four openings
7: What it should look like now
8: Add the yellow gears with the teeth facing down
9: Put that piece on top now.
10: Add motor thingy on like so. Sorry I didt't get any better shots of the connection.


Step 6: Allignment

Alignment? What the heck?

Well, the way it works out, the gears dont exactly line up at the moment. Its hard to explain. Just do as I say.

1: Turn on your motor untill one of the shafts is like so
2: Take your next shaft. Lightly, lift the yellow gears up so that you can turn the one shaft while the others stay stationary. Make it so that it is 90 degrees farther in rotation than the previous shaft.
3: It will look like this then
4: The next one will be like this, and the last one will be pointing down. You may want to double-check that they are all alligned.

That was confusing, hopefully you did it right, though. Your all done now!

Step 7: Done!

Horay! You are now able to waste away hours of your life staring at a ball rolling in a circle.



4 People Made This Project!


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Question 8 months ago on Step 2

Obviously the rpm of this motor is important to keep the ball moving. I don't have this motor but I have tried the red, green, blue and black knex motors without success. With the green motor the ball makes one or two loops before stopping. Do you know the rpm of the motor you are using? I was also thinking about changing the length of the rise by using the red connector instead of the grey connector. This should give more slant to the ring. What do you think?
Update: I obtained the same motor you are using and it works like a champ without any other modifications.


5 years ago

This should totally be featured.


You'll need at least a few tan clips, everything else you could work around I think..


You'll need at least a few tan clips, everything else you could work around I think..

carson kaden
carson kaden

8 years ago on Introduction

can i make this without the clips, spacers,hinges,sockets,and the ball joints


9 years ago on Introduction

Awesome machine! Are you a hypnotist by chance? because this thing is very amusing and hard not to watch. I modified mine with second track on top of the first one for even more fun.


Reply 9 years ago on Introduction

Yep. Just took it hopefully it's visible through my mess!


Reply 9 years ago on Introduction

Thats awesome!! It would be so sweet to have like 20 stacked on each other :-p

Thanks so much for the photo!


Reply 9 years ago on Introduction

Twenty would be cool if I had enough knex. I might manage 3 at most. =) No problem I love using my camera.


9 years ago on Introduction

Great job!!!! I might modify-changing the motor pack with a standard one (mine broke).


9 years ago on Introduction

just got done building it and i have to say it is awesome. modified mine a little to run with a hand crank instead of a motor, but thnks for the great build


Reply 9 years ago on Introduction

Sweet, thank you so much! I'd really love to see the crank you made, do you have any photos?

Thanks again!


Reply 9 years ago on Introduction

here is the picture of the crank and the picture of my completed ball machine


Reply 9 years ago on Introduction

Man, that looks fantastic! I really like the rails you added. Very impressive!