Vending Machines: How Do They Work, Anyway?
April 23, 2016 10:24 PM   Subscribe

An animated explanation for how newer vending machine detect fake coins and keep your treat from getting stuck.
posted by SpacemanStix (35 comments total) 12 users marked this as a favorite
 
Thank you for this. It is not something I lost sleep over, but I always wondered about both the coins and the product falling. This is a terrific explanation.

In my day, we just beat the machine senseless until either it gave up the goods or we hurt ourselves. The things one does at 2:00AM in order to get that last bag of Bugles is actually a study in human nature itself. Thought that big guy at the end was going to turn the machine over.
posted by AugustWest at 10:29 PM on April 23, 2016 [1 favorite]


Some people still go out and get their stuff somewhere else? Drones are a quantum leap in ease-taking
posted by clockzero at 10:42 PM on April 23, 2016


Wait, are you saying Belgian 5 Franc coins don't pass for quarters any more? DAMN YOU TECHNOLOGY!
posted by msalt at 11:39 PM on April 23, 2016 [2 favorites]


Oh, modern technology, so disappointingly efficient.

Gone are the days of the new ice lolly machine at school that, as someone found out early on (how??), didn't know the difference between two Pfennige and fifty Pfennige (which had roughly the same size but different weight). Sweet days.
Then the caretaker emptied the coin drawer for the first time. Old school, high ceilings, lots of echo, caretaker livid to the point of self-combustion. I think the whole inner city of Bremen could hear him.
posted by Namlit at 11:44 PM on April 23, 2016 [23 favorites]


I enjoyed the way the video used such cinematic bombast for something so quotidian. The vending machine explodes outward, the coins fall in slo-mo to driving thumps and boops, the narration is apocalyptic... and then the bearded guy gets his chips and heads back out to the college quad.

I'm about to go cook an egg. I think I'll imagine all the steps that I go through in this style.
posted by painquale at 2:11 AM on April 24, 2016 [17 favorites]


Metafilter: such cinematic bombast for something so quotidian
posted by Foci for Analysis at 2:24 AM on April 24, 2016 [18 favorites]


I will follow the safety tips in the video and carefully step back 2 paces after putting money into vendening machines and then again after selection. This will protect me from explanatory disassembly injuries (EDIs), increasingly common on our college campuses.
posted by GenjiandProust at 3:41 AM on April 24, 2016 [17 favorites]


Now I'm wondering what happens to the big dude, striding off to meet destiny with chips in hand, after the film ends.
posted by thelonius at 6:11 AM on April 24, 2016 [1 favorite]


That has very dramatic sound for a clip about a vending machine.
posted by jeather at 7:39 AM on April 24, 2016 [1 favorite]


"Cinematic Bombast" is my new band name.

Or possibly the name of a little-known Eastern European philosopher.
posted by 43rdAnd9th at 7:40 AM on April 24, 2016 [1 favorite]


Would like to see a follow-up, perhaps scored to "Ride of the Valkyries", about why vending machines are unable to comprehend a dollar bill with a tiny fold in the corner.
posted by chimpsonfilm at 7:59 AM on April 24, 2016 [17 favorites]


When I'm on campus, I get a bottle of water out of one of those machines that use a floating arm and basket that moves to whichever row of bottles I've ordered. Once the basket is in position, the bottle gets kicked off its perch and into the basket, which then moves to a collection slot and kicks the bottle out into the slot and to me.

Sometimes, though, a bottle will get hung-up and not fall into the basket. When that happens, the machine will pause and "think" about the situation and then move the basket in a way that will dislodge the bottle and get it into the basket.
posted by Thorzdad at 8:16 AM on April 24, 2016 [3 favorites]


Chimps, my assumption has always been that vending machines are basically perfect targets for counterfeits, ruined bills, and other kinds of shenanigans, and that therefore someone long ago decided as a matter of policy that if your bill isn't basically perfect it's not worth bothering with. Human judgment and customer service aren't really part of the vending machine business model; they just want to take your money with an absolute minimum of effort on their part. Anything that even looks like it might be something that could possibly be a hassle to deal with later isn't worth it. So the bill scanner is really picky about what it'll accept, and if that means lots of false positives then that's just cost of doing business.

Only a partial answer even if true, but that's been my assumption for many uears. I too would love a more specific and evidence-backed answer.
posted by Anticipation Of A New Lover's Arrival, The at 9:10 AM on April 24, 2016 [3 favorites]


Amazing production, let down by way-too-shallow content. For all its "how it works"-ness, there was way too much hand-waviness left in. It rolls by electromagnets, so the machine "knows" what metal it is. How? What exactly does it measure and what's different between a dime and a nickel? You just waved away the whole purpose of watching the video. Fake coins "are diverted" into the reject hopper - how? In the drawing, it looks like the real coins magically levitate over.

The toilet one is worse, it's like a parody of movie-trailer-voice guy. Complicated series of valves, sure. HOW?
posted by ctmf at 9:38 AM on April 24, 2016 [14 favorites]


I admit I didn't know how the cue ball redirect works in a pool table, though.
posted by ctmf at 9:39 AM on April 24, 2016


I agree, too much dramatic voiceover with not enough actual explanation. It's like watching How It's Made -- I always want to know how they design the machines that do all the tasks in a factory, as well as watch the machines run.
posted by nat at 9:49 AM on April 24, 2016 [1 favorite]


In other vending machine "how it works" news, there's a big heavy weight in the top so if you try to tilt it forward to make the goods fall out, it just completely falls over on its face. Alerts bystanders with the big crash, possibly takes out the perpetrator, and shields the precious, precious chips. Seems excessive.
posted by ctmf at 10:09 AM on April 24, 2016 [8 favorites]


I always want to know how they design the machines that do all the tasks in a factory

I think machines do it.

Regress looms!
posted by painquale at 10:18 AM on April 24, 2016


(Hmm. I meant for 'looms' to be a verb in that sentence. But now I think it reads better as saying that machines that make machines are 'regress looms'.)
posted by painquale at 10:21 AM on April 24, 2016 [10 favorites]


I enjoyed the way the video used such cinematic bombast for something so quotidian.

I think the how part of the video was mostly lacking. It shows coins rolling around an exploded vending machine, but spared few words describing how the processes that sort, collect, dispense and reject coins actually operate. It's another of those YouTube videos where the production effects get in the way of the informational content.

If it had been a guy in his basement showing a disassembled vending machine, rolling one of each coin down its coin chutes, with no titles or CG or swooshy sound effects, I probably would have gotten more out of it.

Here: this one talks in detail about the dispenser mechanism, and this is a detailed breakdown of the operation of an older coil acceptor.
posted by JHarris at 11:07 AM on April 24, 2016 [5 favorites]


It's like one of those "documentaries" that cares more about trying to impress the viewer with swooshy effects, ominous lighting and dramatic music, when really just old David Attenborough talking about the behavior of a lemur, overlaying animal footage, is more than enough.

I've found, on YouTube especially, that excessive attention shown to production effects is a sign of a worse video, not a better one, like they're trying to distract from the fact that they don't have much real content.
posted by JHarris at 11:11 AM on April 24, 2016 [2 favorites]


1£ coins rolling down chutes of metal pass vinyl gears dabbed with lithium grease PALES to the skill of zip tying the coin slots on basement laundry machines.
posted by clavdivs at 12:25 PM on April 24, 2016 [1 favorite]


This reminded me of Seconds From Disaster.
posted by AFABulous at 1:54 PM on April 24, 2016


I was mildly surprised and rather relieved the first time a vending machine gave the quarter turn to dispense my stuck candy bar, after which I immediately noticed the photosensor. As for the coin acceptor, it is unclear from the video whether there has been any interesting change in that arena, as opposed to the definite improvement in bill acceptors I've seen since the days of my youth where they all had to be perfectly smooth and specifically orientated.
posted by ckape at 2:00 PM on April 24, 2016


The video is perhaps exaggerating how well they work.
posted by Rhomboid at 2:07 PM on April 24, 2016


Anticipation Of A New Lover's Arrival, The: It's a matter of fine-tuning between the accuracy (correctly detecting the genuine article) and false positives (failing to reject the counterfeit). Vendors don't want counterfeits, so they tune towards the accuracy end. Scarily, fingerprint readers tend to tune towards the loosey-goosey end so that they don't reject you too often (but leave things open to false positives).
posted by oheso at 3:22 PM on April 24, 2016


> I admit I didn't know how the cue ball redirect works in a pool table, though

I imagine it mechanically weighs the cue ball, which probably has a different mass than the other balls against a reference mass and diverts it to the pickup bin during a scratch, where the other balls go into the "new game" area.
posted by ostranenie at 8:18 PM on April 24, 2016


Either that or light sensors (the cue ball is white) or circumference gauging (the cue ball is larger or smaller than the other balls).
posted by ostranenie at 8:20 PM on April 24, 2016


Amazing production, let down by way-too-shallow content. For all its "how it works"-ness, there was way too much hand-waviness left in. It rolls by electromagnets, so the machine "knows" what metal it is. How? What exactly does it measure and what's different between a dime and a nickel?

I can't quote the exact science going on, but the new acceptors do this by combing some clever mechanics with a lot of electronics.

The mechanics involve bouncing or manipulating the coin so that it begins to roll past the sensor at a known rate. Then you move the coin past a hall effect sensor. The coin will break the magnetic field in a certain pattern for a certain duration of time, given a coin of a known shape, size, mass, and metal composition. Here are some college students that tried it on their own.

A lot of this was pioneered by Mars Electronics, later called MEI. I was a big customer of their Cashflow series of coin acceptors. If you're curious about why the company was called Mars, get this: they were initially a subsidiary of the Mars candy company.

Mars operated a massive amount of outdoor candy vending machines in Europe and had a continual problem with acceptors damaged by vandalism and abused by counterfeit coins and slugs making it past the other OEM acceptors. So Mars engineered their own line of acceptors with a completely open coin path. If I recall correctly, one of their initial design criteria was to be able to handle a whole pint of lager poured into the coin slot and still be able to accept money afterwards.

They're nifty little gizmos. You can even train them to accept new coins or tokens by running a couple of dozen through it when a programming mode is activated.
posted by JoeZydeco at 8:27 PM on April 24, 2016 [23 favorites]


The video in this series says the cue ball has iron under the enamel. A big magnet pulls the cue ball off the railed track as it's heading down, onto a parallel track which then diverts to give the ball back.

Possibly that's not how all pool tables work, but it seems plausible enough that now I want to take a magnet to the bar and check it out.
posted by ctmf at 9:42 PM on April 24, 2016 [1 favorite]


Old Chilean 1 Peso coins (worth US 0.15¢) were, from a vending machine point of view, identical to US Quarters. A friend traveled to the US about 10 years back with a bag full of them, and lived off of practically free vending machine junk food and soda for a week or so.
There's a story about how at some point somebody (a state? a vending machine company?) carted off tons of peso coins to the Chilean consulate and asked for the equivalent in quarters, but I don't know if it's true or apocryphal.
posted by signal at 2:23 PM on April 25, 2016 [2 favorites]


Possibly that's not how all pool tables work, but it seems plausible enough that now I want to take a magnet to the bar and check it out.

Fucking pool tables, how do they work?
posted by krinklyfig at 3:22 PM on April 25, 2016


'The Secret Life of Machines', though old is a perfect example of how to explain stuff like this. Basically no production values at all and you couldn't care less because you're too amazed at the incredible explanations of how machines work. They made a working tape recorder out of tape and rust for God's sake.
posted by chisel at 4:06 PM on April 25, 2016 [3 favorites]




Good grief the input lag on that thing. How does anyone ship a product with that bad of an interface and still sleep at night? The poor woman demonstrating it was suffering just entering the three digits 100.
posted by Rhomboid at 4:42 AM on April 26, 2016 [2 favorites]


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