Pin Sorting Machine

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As I like building Technic Lego, but become more and more fed up with sorting pins, I thought it would be nice to combine my new Mindstorms to create a pin sorting machine. I came across some Youtube footage from Ayuki (1st class hero) and another (from Germany or Austria I think) of several sorting machines.. 

This gave me plenty idea 's to start from and I have created a try-out setup. The raw machine works quite well. But I am not satisfied with bulk delivery of the pins, more on that below.

The basic setup is like this:

Insert pins -> select chute through color -> select output/chute through size -> bin

This gives me 4 sorting options (=bins), thus I can auto sort:

- long black pins
- short black pins
- long blue pins
- blue 'axle to pin' pin

.. in one go! With an altered program and another sorting shift I can sort grey and sand, long, short and axle to pin pins.

How it works
On the pictures below you see the color sorter.
A conveyor belt feeds the pins (one by one with some margin in between) through the machine and down a chute either on the left or right hand.
The Mindstorms color sensor checks color of a pin as they travel by and sends a right or left turn to the servo motor. The axle is operated by the servo and a "bionicle tooth" on the other end sends the pins left or right. And they go down the chute.

Note: the chute down and the final sorters are not on the pictures as they work fine.




Only thing is that the pins do not 'stick' well to the conveyor and when not in a straight line they sort of 'roll' on the conveyor, and not move forward. But overall it works remarkably well when feeding by hand. As mentioned the second sorting process also works very well. So they are not on display -yet!- for now. 


The challenge
The main problem I am facing right now is that this thing should operate more autonome. I want to be able to up-end an entire bin with assorted pins into the machine and it should feed the pins onto the above conveyor. 
Things to keep in mind:

1. pins should be in a straight direction
2. pins should be fed one by one with some margin 

I am currently working on this problem. So far I have tried:

1. Container with rubber conveyor and some roof pieces for better flow:
(the rubber belt is missing in the pic, it was at the bottom off course. In the next picture you can see the rubber belt I used )


2. Double rubber conveyors in 45° angle setup:


3. Combined studded/studless and gravity:



4. And a worm wheel:


So far, I think the container/conveyor combination and worm wheel will be my best bet.. 
Alas both have problems. The first, (no. 1) did not feed pins very well; they pilled up and become stuck very often. The latter (no. 4) does not take all pins very well and a lot where left on the surface. I maybe should try some more using a studded container with smoothed/no stud tiles and angled bricks or something?

Help wanted
Does anyone have any bright ideas? Help would be much appreciated! :grin:


Edited by bord4kop

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I would like to split this post into a separate topic and move it to our newly created Mindstorms forum :sweet:

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I would suggest a vibrating table feeder to move the pins to the colour sensor.

Could something like the sail from the recent technic yacht give you a smooth deformable surface as an alternative?

Edited by thekitchenscientist

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I could have done with something like this as I’ve spent over 5hrs a day for the last 3 days sorting out two 2 litre plastic tubs each almost full to the brim of mixed pins. Moving them one pin at a time from one tub to another. You’ll understand then my having a tear in my eye at 4:15pm today when the last pin, a lowly black 2L, landed in it’s designated tub. I’m sure I’ve never been so glad to finish something in all my life!!!

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This post won't give you a solution, but maybe it will help you see the work you are facing. 

From what I've seen, hoppers/feeders and alignment mechanisms are some of the most challenging devices to create.  The solutions often involve two or more mechanical "tricks" combined together to achieve something that looks like magic. @thekitchenscientist mentioned vibration, but you can also have surfaces with different coefficients of friction, static "fingers" that tip the object in a particular direction, screw feeders, star wheels, conveyors running in opposite directions, gravity chutes and hoppers. There's probably a ton of other options in this arsenal of "tricks", and combining them is a whole science. 

Electronics are often used to test the outcome of the device - for example, a bottle that is placed upside down on a filling line will be detected before getting to the filling mechanism. It will then be knocked out of line and returned to the hopper/feeder. So the mechanism doesn't need to be perfect, as long as you build in a way to eliminate bad results. (At some point efficiency becomes an issue, but that's a different story.) 

Good luck, this is quite an ambitious project. 

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Thank you all for giving me idea 's and a direction! Once done, I might also make instructions :wink:

Now I will have to try some things to see if it works. A rotating bin with scoops is my best bet at this time. 

Thanks again and I will keep you posted!

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