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They have a category all by themselves, get taken apart after the first run and then simply made to go through again in the next batch. The neural net is surprisingly good at classifying 'mess' as a category!

That's a nice solution. I'm reminded of a short video I watched on the Lego factory. One segment of it discussed the machine that put the minifigs' heads on their bodies. There's a big hopper of bodies that get drawn up onto a belt and then a camera makes sure each body is facing the right direction before putting the head on.

What do they do with bodies that are facing backwards? Is there a little side channel that flips them around? Nope, they just get tossed back into the hopper to try again. It's effectively random which way they'll be facing when they get picked up, so they'll eventually get through.

I thought that was a nice illustration of keeping things simple and taking advantage of processes you already have, and seems similar in spirit to this.

That's exactly what I love about this whole project. It's an endless series of seemingly simple puzzles. Then you start solving them and they turn out to be much more complicated than you thought. Until you hit the solution and then it's simple again.

Sounds about right. Thanks for sharing it!

And because it's effectively a coin toss, the average number of passes through the machine is just 2!

Just a remark from a Lego nerd: it's attaching arms to bodies, not heads. The neck has a stripe on the front, so that is where the camera looks at to determine which side is facing up.

Somewhere there is a part that has cycled forever ;)

Now you've got me thinking of Frank Abagnale (from Catch Me If You Can). He forged checks where the computer-readable routing number written in magnetic ink didn't match the bank the check was supposedly from, which resulted in the checks cycling nonstop back and forth through the Federal Reserve's system. They only caught on to it because one of the checks went through so many times it started to fall apart and got flagged as unreadable.

Maybe there's some defective minifig body with a mechanical flaw that causes it to always get picked up facing backwards, that's spent years being picked up and rejected over and over.

What about pieces that, put together, equal another larger piece? Say, a few "flat" pieces of the same color to make a larger 1 unit tall brick? Can you see the seams on these?

No, it would miserably fail at that unless I fed a whole bunch of such composites in and tried to teach it the difference between the two. Even then I'm not sure if it would work but it doesn't happen often enough to be a problem.

I wonder if you could make a simple mechanism to split apart the easier parts...

I suspect that's a harder problem than anything I've done so far.

Does it make your finger hurt splitting the parts? Mine ache after about 10 minutes of playing with lego

You need a brick separator! At least two, if possible. http://www.bricksabillion.com/tools/the-brick-separator/

I have a whole bag of tricks for that.

Care to share? :)

Lego makes two 'removal' tools, those are handy, then, I have a very sharp naked 4" blade that will take care of the hardest cases, baseplates will flex the tiniest bit and that will usually give you enough space to flip the top part off. Finally, a regular plate pushed at a 45 degree angle into the space between two other plates will separate the two without damage to any of the parts if you do it 'just so'.

Adapt as needed :)

Perhaps subject them to a near vacuum state? Pressure differential of trapped air in pieces might pop them apart.

If you look at the lego patent: http://npopson.com/images/legowallpaper/LEGO_WP_1920x1200_WH...

There's clearly not any air-tight seal. Most of the nubs on the top of pieces only have 3 or 4 points of contact with the piece they're connected to.

From experience, Lego are nowhere near water-tight, say nothing about air-tight. The air between the pieces will leak out before you can build a high enough vacuum to pop them apart. I suspect this is by design: air-tight connections probably create enough of an internal vacuum that doesn't come apart with hand-force.

If the push-in joints were air-tight they would be harder to put together as you would be pressurizing the air in each connection. Then the internal pressure would be working against the friction fit to pop them apart again.


I made a mould out of Lego (to make Lego-shaped gummy candies) and with a thin coating of vaseline on the outside, it was indeed water-tight (and silicone-goop-tight too).

Vaseline would count as a liquid gasket, in this case. It's really going to completely change the conditions.

I think there were there were beads of water on the outside of the mould, but it was much closer to water-tight than I had imagined, even without the vaseline.

They're astonishingly well made for a children's toy.

They're astonishly well-made for anything. Making bricks that hold together firmly and come apart easily requires micrometer tolerances, and Lego is basically on the cutting edge of plastic manufacturing even today. That's why non-Lego brand bricks are always kinda crappy; no one else can make them as precise as Lego can.

This is being pedantic, but I imagine they probably could, but they don't because it's expensive. An upstart hitting the marketplace without the incredible brand of Lego, plus higher prices would be a monstrous risk.

There are one or two that come close but the precision and variance of Lego blocks is the stuff of myth that professional mold makers talk about on their lunch breaks. You have to really get close to the parts to see how incredible they really are, with the naked eye you won't see enough detail. The trick is repeat accuracy and that's where Lego is far better than their competition.

That said, they've been cutting quality, moving production to China, using cheaper formulation plastic. That's a bad move imnsho. The brand image is quality and people pay for that, if they ever seriously let that go it's going to be game over for them.

Obviously it's easy to say without knowing how frustrating poor quality parts would feel, but I'd take the quality reduction alongside a price reduction, I think. My 4yo loves sets like 31052 (3-in-1 camper), but the next step up in challenging, brand-neutral sets are around AU$400 which is hefty.

Of course, chances are they'll reduce their production costs but maintain the high prices.

> but the next step up in challenging, brand-neutral sets are around AU$400 which is hefty.

Do you have any specific set in mind?

I would like to challenge him with the creator expert set of modular buildings. 10246, 10255, etc. But 10255 is US$399 for example.

He already has 31052 and 31051 which I think are excellent 3-in-1 sets. Would love to see more like those. They are about AU$80-120 which is a workable birthday/xmas pricepoint.

> micrometer tolerances

That's really not that much (1-999 μm). Keep in mind that sub-1mm is micrometer, and 1mm is a huge distance. I'm sure that LEGO bricks have tolerances of single or low double digits of micrometers...


The moulds are permitted a tolerance of up to two micrometres, to ensure the bricks remain connected.

But, air tight != water tight. And Vaseline can make a world of difference.

Wall shapes -- pushing them through rollers may exert enough force to start splitting them apart. Do this multiple times and they may fall apart.

For odd shapes -- clamping both ends then vibrating the grippers (just a little) could split bits.

It's an interesting problem. What percentage is still connected? May be better to pay a slightly higher price for bits are that not connected (distribute the job out to the sellers)

Are "mess" and "unknown" the same bin? I would expect that they get grouped together as a "human intervention" bin. It would be very surprising if you went so far as to train the neural net to recognize pieces stuck together as something different than an unrecognized piece.

Yes. Well, the net is trained to see them different for later (I have some more nifty ideas) but they are grouped together when sorting.

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