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I've always wanted to build a lego sorter/filter that is basically a box with various sieve levels inside, where you pour the unsorted pieces in the top, they c

I've always wanted to build a lego sorter/filter that is basically a box with various sieve levels inside, where you pour the unsorted pieces in the top, they cascade through the sieves, and out the bottom/along the sides come pieces, sorted by shape/size. The mathematics of this fascinates me, and I think it could be done .. but where to start with the math? Anyone know of anything like this .. ?

Tichy 15y ago
I want to do this ever since my son got his first Lego pieces. It is amazing how quickly you can evoke the impression of chaos with lots of tiny Lego pieces (my machine should also hover the pieces off the floor before sorting them). Hopefully Lego Mindstorms will be up to the task, I still haven't bought one, though. I think easiest would be to sort by weight first. But the pure mechanical approach of a sieve is attractive, too. Might be a good project for trying out a laser cutter.
- seclorum 15y ago
  I have access to a laser cutter, this is exactly what I had in mind - to create a set of masks that would, layered upon each other, filter out each part until they're sorted. Rather a large effort, though .. and I wonder if there is a way to model this without having to laser-cut a lot of test pieces. Well, I think about it every time we end a Lego Mindstorms session in my house, anyway .. ;)
tmh88j 15y ago
Not to be a downer, but I don't see that working to well for different shapes, only general sizes. 1. It would be nearly impossible to account for length of rectangular pieces. Every rectangular piece of same width x height could go through that hole vertically 2. Smaller pieces could fall through every hole larger than itself. So, unless you're using a multi-tier system it's pointless. Basically, I think it could be easily done for general sizes of pieces, not shapes. I'd love someone to prove me wrong because that would be an awesome tool to have.
- seclorum 15y ago
  Well, first thing I thought of doing is getting all pieces in our mindstorm kit measured, so I have a grand "list of sizes", then sorting the list along all axes, and creating some sort of curvature hash that can be applied such that certain 'sort patterns' will occur through the series across multiple axes, such that the smallest parts fall furthest. This hash could be N elements wide for both axes, where N is the # of potential sieves in the box. Then I would scatter the series so that per-sieve, the longest parts are eradicated/expelled in an early layer. The expel part happens because the sieves are not laid flat in the box, but staggered/staged in order to utilize gravity. Around the gravity staging, I would put the N element filters in a way such that the outer edges of the box naturally catch the larger pieces and hold them closer to the layer exit. I guess I should just dump the parts on a scanner and get on with it, but it intrigues me that among the HN crowd, someone might have a much better idea or reason to pursue the electro-mechanical route.
jonnycowboy 15y ago
It's fairly easy actually, all you need is an accurate weight sensor, all different parts have slightly different weights. No vision/scanning technology necessary.
- seclorum 15y ago
  I mean to do it un-powered. I am fairly certain I could recognize all our lego parts from a high-res scan with vision path, laser-cut a qr-code into each piece, and then build a camera-driven bit-pump, but ultimately .. while picking up pieces and putting them back in the box, I would have liked to just know how to produce an ultimate gravity-sieve variant of the solution wherein a form is composed of layers of sieve structures, pieces are poured in one end, out come each piece, sorted by size/type. I should probably pay more attention to mathblogs, I'm pretty sure there's a proper way to describe a gravity sieve for lego components.
lzy 15y ago
http://www.box4blox.com/ http://www.box4blox.com/
- seclorum 15y ago
  Well, thats exactly what I had in mind! I wonder if they're working on a Lego Techniks version .. thanks for the headsup!

Tichy 15y ago

I want to do this ever since my son got his first Lego pieces. It is amazing how quickly you can evoke the impression of chaos with lots of tiny Lego pieces (my machine should also hover the pieces off the floor before sorting them). Hopefully Lego Mindstorms will be up to the task, I still haven't bought one, though. I think easiest would be to sort by weight first. But the pure mechanical approach of a sieve is attractive, too. Might be a good project for trying out a laser cutter.

seclorum 15y ago
I have access to a laser cutter, this is exactly what I had in mind - to create a set of masks that would, layered upon each other, filter out each part until they're sorted. Rather a large effort, though .. and I wonder if there is a way to model this without having to laser-cut a lot of test pieces. Well, I think about it every time we end a Lego Mindstorms session in my house, anyway .. ;)

tmh88j 15y ago

Not to be a downer, but I don't see that working to well for different shapes, only general sizes. 1. It would be nearly impossible to account for length of rectangular pieces. Every rectangular piece of same width x height could go through that hole vertically 2. Smaller pieces could fall through every hole larger than itself. So, unless you're using a multi-tier system it's pointless. Basically, I think it could be easily done for general sizes of pieces, not shapes. I'd love someone to prove me wrong because that would be an awesome tool to have.

seclorum 15y ago
Well, first thing I thought of doing is getting all pieces in our mindstorm kit measured, so I have a grand "list of sizes", then sorting the list along all axes, and creating some sort of curvature hash that can be applied such that certain 'sort patterns' will occur through the series across multiple axes, such that the smallest parts fall furthest. This hash could be N elements wide for both axes, where N is the # of potential sieves in the box. Then I would scatter the series so that per-sieve, the longest parts are eradicated/expelled in an early layer. The expel part happens because the sieves are not laid flat in the box, but staggered/staged in order to utilize gravity. Around the gravity staging, I would put the N element filters in a way such that the outer edges of the box naturally catch the larger pieces and hold them closer to the layer exit. I guess I should just dump the parts on a scanner and get on with it, but it intrigues me that among the HN crowd, someone might have a much better idea or reason to pursue the electro-mechanical route.

jonnycowboy 15y ago

It's fairly easy actually, all you need is an accurate weight sensor, all different parts have slightly different weights. No vision/scanning technology necessary.

seclorum 15y ago
I mean to do it un-powered. I am fairly certain I could recognize all our lego parts from a high-res scan with vision path, laser-cut a qr-code into each piece, and then build a camera-driven bit-pump, but ultimately .. while picking up pieces and putting them back in the box, I would have liked to just know how to produce an ultimate gravity-sieve variant of the solution wherein a form is composed of layers of sieve structures, pieces are poured in one end, out come each piece, sorted by size/type. I should probably pay more attention to mathblogs, I'm pretty sure there's a proper way to describe a gravity sieve for lego components.

lzy 15y ago

http://www.box4blox.com/ http://www.box4blox.com/

seclorum 15y ago
Well, thats exactly what I had in mind! I wonder if they're working on a Lego Techniks version .. thanks for the headsup!