Turing Tumble Community

Challenge #3: Ball sorting/reset system?

Building and running mechanical computers is fun, but sorting the balls at the end and putting them back up on top is, dare I say, not. One of the most consistent bits of feedback I get is that no one likes to return the balls back to the top.

Challenge #3 is this: Can you figure out a simple, elegant way to do any of the following things?

Extract the balls from the output more easily
Sort the red and blue balls automatically (maybe they could be a slightly different size?)
Return the balls to the top more easily

Excited to see what you come up with!



First thought for a sorting system:
Ferrous and non-Ferrous balls and use a magnet for sorting.


Some kind of lego robotics system with a camera to see the colors might work :slight_smile:


That’s a great thought - that could definitely be the basis for a nice sorting system.

Huh, it looks like this forum puts all replies in order of when they were posted rather than putting them next to the comment they are in reply to - sort of like on the Kickstarter page. That’s kind of strange.

Yeah, I bet that would work. By the way, have you ever seen those rice sorting machines? They create something like a waterfall of rice and then shoot little puffs of air out to knock the discolored rice into a reject pile. I first found out about them on Reddit. Check out this video: https://www.youtube.com/watch?v=M-3HDO70ClU

I like the idea, but it would be even better if we could make the sorting completely mechanical. Thanks Lode!

If you’re open to sizing differences, as you mentioned, it could work like the sizing screens used in mining. An attachment at the top of the table with 2 levels. The top level has a funnel that places marbles onto a channel. The channel has a hole for the smaller marbles. Larger marbles roll on the top channel to their location of the table, smaller marbles drop through to the second channel and are diverted to the other side. I think size differences would allow for the most elegant solution.

1 Like

The size difference is an interesting idea. Paul, if you go that route, I suggest finding a denser plastic for the smaller ball, so that the weight of the balls remains equal. You might get unexpected output otherwise, if the larger ball can successfully move a chain of 5 gears, but the smaller one can only move 4 gears. this brings to mind the idea of a coin sorting machine, where coins roll down a ramp, and fall in holes that are properly sized for each type of coin - smallest to largest.

That’s a good idea, msmcguiver. The density of the material could be different or the bigger balls could be hollow.

Add a flat removable holder with a low divider that slots in at the base as a receptacle. Marbles fall into this when released by a ‘trap’. Separate colours by sliding using finger over this low divider. It would have two ‘spouts’ to pour marbles back in at top. User holds finger over opposite colour while tipping. Add holes at top of board over red and blue sections for spout to pour into.


Just came here to suggest essentially the same thing (although I didn’t think of using a low divider for easier manual sorting). You don’t even need to hold your finger over the other ball colour if you just make the holes at the top of the board the same distance apart as the divider, so that you can pour both colours at once.

1 Like

Great idea about lining up the holes Menderbug.
I think I’ll try a 3D print. Good to have a removable receptacle that nestles in base and can transfer marbles to top.

1 Like

That would be awesome. Now that people are getting the game, the most consistent bit of feedback we’re getting is that people want a way to get the balls out of the bottom, sort them, and put them back in the top. I think your idea of just making a little device to sort balls faster by hand is the best approach. If you design something that can be 3D printed, I’d love to send it out to the community. I think a lot of people would 3D print their own.

Would a longish (flexible?)magnet do the trick?


I use a spoon and a paper plate dented in the middle so balls roll to the inside circumference

1 Like

Not so much sorting but in the vein of ball handling,

I’m using a large drinking straw (slightly smaller diameter than a ball) with a split up the side. A second finer straw acts as a plunger, stabilised by passing it through a slit at the end of the larger straw. With this you can ‘tap’ on balls of the same colour then eject them into the ball shoot (or container when packing up).

With a bit of practice you can get proficient; quite a bit easier then with my fat fingers!

  • Works best when tapping on the right most ball using the right wall as a vertical guide and to stabilize the ball
  • Use two straws, one for each color
  • Put your Turing Tumble on a towel to help stop those dropped balls escaping
  • Pull the plunger up before you start tapping balls
  • Straw can easily hold 15 or more balls

Two straws. What could be easier.

Photo of ball selector

Video of ball selector in action.

Hint: avoid a spiral cut in your straw as it looses some integrity and tends to collapse.


I was just about to upload a video and suggest using a slightly larger drinking straw. It works quite well!

1 Like

Thanks for the towel and straws suggestions. I have been doing some interesting yoga to retrieve a ball or two… about 20 so far…


I use a thick boba straw. Have experimented with both a pointed end and a “flat” end, they both work but I prefer the flat end. First I pick off the blue balls and reset them at the top, then I pick up the reds and to the same. It’s it also easy to change the number of balls loaded at the top with a straw like that

1 Like

Great idea using a straw.

So far I was using the ‘Start Button’ as a shovel and it works not so bad for 1 to 3 balls.

1 Like

I seem to use a different method from others. I have a laundry card where I use the corner to flick specific balls out from the bottom (and I catch them as they roll off the table) and then I use the card to provide more surface area at the top to drop the balls on so they roll into the holders at top with fairly little effort.

1 Like