Coin Sorting Machine (Runs on Gravity)





Introduction: Coin Sorting Machine (Runs on Gravity)

Tired of sorting coins manually? Coin sorting is a tiresome job. Let's make a wooden coin separator out of common materials! The sorter uses plain old gravity to separate the coins to their designated container. You know what that means! No more batteries!

What Made Me Build This?
Every time I go home from school, my pocket always gets full of coins. Once I arrive at my bedroom, I sort the coins to my 3 huge piggy banks. It's pretty tiresome thinking that I do this on a daily basis. So I thought of building a simple contraption that sorts coins by using gravity. The idea is pretty old, BTW.

Why Are There Only 3 Compartments?
There are six Philippine coins: 10 php, 5 php, 1 php, 25c, 10c, 5c. In my bedroom the 10 & 5 peso coins share the same piggy bank, both coins are the same in size by the way. The 1 peso coins has it's own piggy bank since it's the coin that has the highest quantity & it's pretty common. The 25, 10 & 5 centavo (cent) coins also share the same piggy bank since I barely get those.

Full Video Demo + Explanation:

Demo Video:

Step 1: Tools & Materials

I didn't spend anything since I have all the tools, parts & materials in our backyard (inventory).

Parts & Materials:
- MDF Material (your choice of wood)
- Bendy Straws
- 3.5mm Screws 
- Foam Board
- Super Glue

Tools & Equipment:
- 3.5mm & 6mm Drill Bit
- Jigsaw (Hacksaw)
- Right Angle Ruler
- 48" Metal Ruler
- Electric Sander
- Eye Protection
- Portable Drill
- Gas Mask

Step 2: Cutting the Wood Panels

Ok, start designing your box. Remember, since each country has a different number of coins, we probably don't have have the same number of dispenser divisions. But if you want to make the exact wooden box that I made, just follow the measurements below. 

Rear Panel = 9" x 6.5"
Bottom Panel = 9"x 3.5"
Side Panels = 6" x 3.5"

Use a pencil and a ruler to mark the cutouts then cut the wood with your trusty jigsaw. The 2 middle dividers should have a small rectangular nick. That small cutout will be the passageway for the coins.  

Step 3: Tips: Countersinking the Screw

Use a larger bit to countersink the screw. This prevents the screw from protruding over the wood's surface. This does not apply to flat headed screws. 

Step 4: Drilling Holes for the Screw

I've now graduated from using woodglue to using screws & nails. I wanted to make this project as dry as possible so I used screws instead of woodglue. 3.5mm screws works best with 1/2" thick wood. Also, try to buy flat headed screws for you to omit the countersinking process. 

Step 5: Assemble the Sorter's Enclosure

After drilling all the holes as planned. You can now start to screw the wood panels to form the coin sorter's box.

Step 6: Super Glue the Straw (Coin's Path)

1st.)  Get a bendy straw and cut of the bendy area. 
2nd.) Drop superglue on the wood's surface.
3rd.)  Position the straw in a diagonal manner, enough to make the coin travel. 

Step 7: Making the Coin Sorting Mechanism

How Does It Work?
Try to experiment by changing the straw's gap. Certain coins should fall when the gap is to big for them other wise the coin will proceed to the next division. 

1st.)  Cut small fractions of straw, the size of the wall's width.
2nd.) Adjust the distance of the top straw from the lower straw. 
3rd.)  Apply small amounts of superglue ones you have finalized your straw's fixture.
4th.)  Get a small piece of plastic then glue it on the upper right part of the straw. This flap will guide the coins to the proper direction.

Demo Video + Explanation: 

Step 8: Silent Coin Drop Mod - Foaming (optional)

When the coins drop to their designated container, the sound can sometimes be irritating. I found a foam board from my Arts & Crafts supply cabinet. I've cut small rectangular foams to dampen the sound of falling coins. 

BTW you can add rubber feets to your coin separator.

Step 9: Adding a See-Through Wall

I ran out of clear acrylic so I substituted it with a thick piece of Acetate (OHP Film).

Step 10: Making the Top Cover

I used an illustration board to cover my coin sorter's top panel.



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It's very cool, but I don't quite understand how the straws sort the coins!

Maybe I'm having a bad brain day, but I don't get it.

If the straws were cut in half, and then had different size slits cut in them, it would make sense to me, but it doesn't look like that.

Can someone help me comprehend this please?

The straws form a rail that the coin slides on. As long as the distance between the two straws is shorter than the diameter of the coin then it will continue to roll through the rail without falling because of the support of the stabilizing rail (top straw). When the distance between the straws flares to be bigger than the diameter of the coin then it will fall through the gap because nothing is stabilizing the coin.

I don't the think the explanation is at all clear until you understand how it works. Then, magically, it suddenly seems easy and clear. The sorter works based on the height of the coin. As the coin rolls, the top of it leans against the higher straw but it can't fall because that straw us there. Just before the coin reaches the wall, there is enough gap for a coin of the right size to fall to the side. So the coin just rolls until there is a gap larger than the coin is tall between the two straws, then it falls.

Thank you! I was in the same boat. I read it twice and still though I was missing something. Glad you answered! lol

Thank you.

Sometimes, some things just don't click!

Here is a picture from the author's instructable.

There is a few mm of space between the top straw and the wood. When you insert a coin, it will roll along the bottom straw. The gap between the two straws increases as the coin rolls further along. Small coins will fall into the first box because it will fall through the gap between the two straws. Bigger coins can't fit through that gap, so they will continue to roll along until they reach a gap between the straws big enough to allow the coin to fall through. I hope this makes sense.

Did you watch the author's demo video? He explains is pretty clearly.

Watch this video too.

I watched the authors video several times - it's too far away for me to see what is going on. Thank you for the lego video. It looks magical and unfathomable as well! Maybe I've had a minor stroke or something!

Remember those 3d pics you had to stare at while relaxing your vision, then all of a sudden it turned 3d? This seems to be analagous to that. Sometimes they would pop right into your perception, other times you could stare for minutes and still not see it!

Thanks for trying to help me.

What school do you go to where you are able to obtain so many coins in one day?