Axle and Pin Sorting Contraption Discussion

[Phoxtane]

Well, with the Thanksgiving break in full swing, I figured I'd get a ton of Lego sorted and cataloged properly. At some point I'll want to sort my Technic, and that means delving into my 'connectors' drawer - which includes everything from axles, axle connectors, bushings, and pins. I'm not looking forward to that at all. So obviously the solution would be to sort out the parts via a contraption!

Now, there have been a few devices built for this purpose; akiyukiy's Axle Sorter and these two pin sorters come to mind. However, there hasn't been one yet that will sort the axles from the pins.

As far as I'm aware, there are two defining characteristics that separate the two:

- Connection type is the biggest - one is an axle, the other is a pin. If a way to test this reliably could be devised, that would solve the problem of sorting the two.

- A more feasible goal is to assume that all things that are longer than 3L are axles. The 'short' bin could then be sorted by hand, or by another sorting device based on the first point.

Failing this, an axle sorting unit and a pin sorting unit that could run in tandem would be nice as well. I think the pneumatic Mindstorms-controlled pin sorter is the best one, but the problem is that certain pins come in two colors, especially 3L. How would you sort those then?

Edit: I accidentally the formatting.

Edited November 26, 2013 by Phoxtane

[Junpei]

I think you should just ditch the color sorting, or just sort them yourself. That's what I'm doing over thanksgiving break, sorting everything.

[Blakbird]

I think you should just ditch the color sorting, or just sort them yourself. That's what I'm doing over thanksgiving break, sorting everything.

Sort them yourself? Why would you do something manually when you can make a ridiculously complex machine to do the same work much slower and with more cost? This is the Technic forum after all!

I'm quite fascinated by these sorting mechanisms, especially those that are purely mechanical and use no sensors or programming. Akiyuki is so good that he even does it with one motor.

Given that each type of axle and pin now comes in only a single color, there is no need to sort by color. You only need to distinguish shape and then you get color for free. Sorting in tiers starting by length would be obvious, but how to sort within a given length is much harder. For example: a friction pin, a frictionless pin, an axle pin, a frictionless axle pin, and a 2L axle are all the same length. How to distinguish between them? If you can do it mechanically, you are my hero.

[Alasdair Ryan]

Just imagine a machine that could sort out axles,pins,bushes and small liftarms.....

I like the pneumatic one the best,can you explain a bit more about how the first sorter works?

I think you should just ditch the color sorting, or just sort them yourself. That's what I'm doing over thanksgiving break, sorting everything.

In all honesty that is quite a poor reply....

You don't have to post a reply to every topic if you don't have something constructive to say.

[Junpei]

I wasn't just trying to post in every topic, just saying that's what I would do. But I agree those mechanisms are awesome, just that's the way I'm doing mine. You're right, that's kind of boring and kind of a stupid post, sorry.

If you really wanted to sort by color, I think you could use EV3, with the color sensor. It doesn't seem that hard, but I would love something purely mechanical (with one motor) like a GBC module.

Maybe something with the pullback motors or hockey springs could distinguish between axle pins and normal pins, by if it fits into the axle hole or not. But friction vs frictionless? Maybe even Akiyuki wouldn't be able to do that.

[Phoxtane]

Given that each type of axle and pin now comes in only a single color, there is no need to sort by color. You only need to distinguish shape and then you get color for free. Sorting in tiers starting by length would be obvious, but how to sort within a given length is much harder. For example: a friction pin, a frictionless pin, an axle pin, a frictionless axle pin, and a 2L axle are all the same length. How to distinguish between them? If you can do it mechanically, you are my hero.

You're assuming that my collection is new enough to have all these parts in their 'new' colors. Alas, that is not the case! I have a handful of 3L friction pins in black, and a handful of frictionless axle pins in light grey. That's the big problem with a robotic sorter - I would end up with 2L and 3L friction pins together - though it is manageable, I think. It would be manageable to set up an akiyuky-style machine where the pins and axles go in together. At the 3L and 2L bins, the pieces instead are brought to a robotic sorter that will then sort by color and would re-route the parts to the correct bin. Or, at that point, you could sort them by hand. But that's no fun!

can you explain a bit more about how the first sorter works?

I'm assuming you've watched the video - if not, this will make no sense whatsoever! The axles, after they've been lined up, are sent one at a time into little segments built out from the conveyor. They're then brought over a series of holes that are offset from each other. The holes start out towards the 'top' of the conveyor segment and slowly migrate over the course of the conveyor towards the 'bottom' of the segment. As such, the longest axles overbalance and fall into their respective bins first, then the second-longest, and so on.

[DrJB]

Just a though that comes to mind... Do you guys know how TLG workers know that the contents of a bag are correct? they use high precision scales! So, so far we have three sorting attributes: length, color, and possibly weight. Given the friction in lego parts, I bet we'll never have anything reliable based on weight. That said, there are also that lego set of sieves, to presort large from medium from small parts. One can devise a sieve system that for example could separate the bushings from the pins ...

Ultimately, there has to be some manual (human) based either pre- or post- sorting. Akiyuki has a machine that does some pattern recognition and even sorts lift arms from connectors ... It is based on an NXT and a webcam ... If my recollection is right. But it's extremely slow ...and I can do a much faster job than it ..

Edited November 27, 2013 by DrJB

[Alasdair Ryan]

I'm assuming you've watched the video - if not, this will make no sense whatsoever! The axles, after they've been lined up, are sent one at a time into little segments built out from the conveyor. They're then brought over a series of holes that are offset from each other. The holes start out towards the 'top' of the conveyor segment and slowly migrate over the course of the conveyor towards the 'bottom' of the segment. As such, the longest axles overbalance and fall into their respective bins first, then the second-longest, and so on.

Ah thanks I thought it was going to be something like that...

[Phoxtane]

I played around a bit with some slope bricks and chain links and ended up with a hopper that I could dump some pieces into and hand-crank out one by one. I ran into some issues with clogging of the exit hole and the axles not having any grip on the chain-link belt. As such, pins would make it through occasionally, while axles would try to be jammed through two at a time and end up blocking the rest of the pieces while they were stuck. I just now tried to fix the issue by raising the slopes making up the sides of the hopper up a couple of bricks in order to end up with a narrow channel in hopes that it would force the axles to line up one at a time. That didn't work either; axles kept falling down two at a time and getting stuck. I'm beginning to think that instead of having axles fall down onto the work belt, it would be better to raise them up to the work belt in order to align them properly, as seem in akiyuki's video.

[camaudio]

I need these machines right now!

[Boxerlego]

Look at this Phoxtane, Axles have corners,edges you will need to use that edge to your advantage so you can distinguish the difference between axles and pins. Lego has the perfect set of parts for this, here is a picture of one . The edges of the axle fits perfectly inside the rail.

Edit: It would even be possible to distinguish between parts like these two parts here.

And this axle here And also this one too .

Edited December 1, 2013 by Boxerlego