Tag Archives: vending

Vending Machine Update

As per my post on open-manufacturing,
“I’m part of a student-run shop, MITERS, at my university, and we considered stocking things like breadboards and arduinos (and other emergency project materials), but that’s really not in our budget as a club. We sort of have a “if the person who knows where the secret cache and can deal with money” system set up, but I wanted to make a countertop vending machine. Used vending machines on ebay are hundreds of dollars and gigantic (we’re tight on space). I decided that the relative portability/stealibility would be fine at MITERS since everyone that comes in is a student.”
From January 13th 2013:

i “finished” my vending machine prototype from mas.863 all in one go, it took ~a day to find all of my supplies (i swear, i had to think like a squirrel to figure out where i buried all my microcontrollers). by finish i mean only that the dispensing aspect works without being plugged into a computer. lasercut wood, buttons and spring off the internet, servos modded to be continuous rotation, arduino uno, and a wall wart. toward the end you can see some of the issues: i made the spacings large to accommodate larger items but… it doesn’t actually work that way, etc.

Here is a video of it failing:

One thing I did learn is that wall warts _will_ reset your arduino uno continuously if you are trying to draw current from them.

a 9V wall adapter: 5V to 23V…

I ended up adding a giant (1000+ uF) cap to smooth out the huge voltage swing, and that solved my stranger errors. I made a short video on this topic. http://www.youtube.com/watch?v=AHoJZ-IKcRs
“300uF (not shown) may not solve your external power supply issue, but 3300uF will! 
In other words, if your arduino sketch runs on usb power but not external power (i.e. crappy wallwart), add a large smoothing cap across the rails and that might fix the issue x.x
Embarrassingly, I had this issue with a side project at my internship last summer and didn’t know how to fix it.”

In progress pics:

drill out hole to inner diameter

I actually got some that lit up, but only at 24V or something silly

Yea, even at 9V (I think I had a 9V wall wart) they are just barely lit up.
The buttons were from my trip to China, but nowadays you can get arcade buttons from places like sparkfun and adafruit.
The vending machine is set to be dismantled. Maybe one day I will build one from scratch.
The status of the money accepting problem, as per my post on open-manufacturing as well:
“I made this prototype (uh… keep in mind this was mostly made over 48 hrs in final project crunch mode, it was a cardboard prototype that looked like this 24 hrs earlier) but my budget was more like $50 than $200, so I got stuck figuring out how to accept payment, because you really can’t mechanically accept bills. (Maybe some sacrifice can be made where I make a bill reader that’s not $$ because it doesn’t have to check for counterfeits. But then I think something this flimsy is a bit sketchy with lots of cash in it. Hmm. I think for our own use probably an RFID reader + student ID would do the trick). It also has so many mechanical issues (but yay learning things from prototypes). “
eric hunting replied:

That laser cut box shape looks like it could be endlessly customizable. For instance, one might make a front panel with engraved graphics and extend its edges beyond the bounds of the box to accommodate any sort of decorations or stick-on sign graphics.
 It’s interesting how many vending machines today use those spiral/coil carrier mechanisms. When looking into this I found you could buy these as more-or-less generic modular units made in China that could be used in any cabinet design–though they’re still a bit expensive. So, apparently, there is more of a food chain of standardized parts for larger vending machines today akin to that of general electronics. It seems to me that the popularity of this kind of mechanism may come from its combination of greater reliability and flexibility. Vending machines with these are definitely more ‘solid state’ than those of the past and accommodate a wider variety of items in the same machine, with the ‘tuning’ between product types a matter of software/firmware. Different size item, different spacing in the coil, different number of turns to dispense. I wonder if the pro machines have modules pre-wired for a certain number of turns relative to the product size or if they are programmed by other means. The compromise, of course, is that the machines of the type tend to be rather generic in design because they’re relying on the packaging of the items to attract customers rather than design and graphics on the machine itself. The Japanese recently took a new angle on this, though, with the addition of display windows that double as touch screen displays. So the machine acts rather like a video bill-board when not in use then turns more transparent when you approach it with the window serving as a control panel for choosing items. 

===
Well, that’s all I have to say about vending machines for a long time. I need to dismantle it sometime this summer and free up my shelf space at MITERS.

Happy summer everyone!

vending machine / start of epic asia trip

well speed update
made cardboard proto of vending machine, final project of mas.863

then CAD’d and emergency lasercut one, but still didn’t have time to do electronics :/ (buttons are just stuck on there, and i didn’t leave space to route servo wires, and i’m using janky self-made continuous rotation servos / zip tie couplers to springs

but first time really CADing the full thing before creating it! compare hexa-not-quite-dancingpod, which was cut by hand and then CAD’d

anyway, open house happened, then I emergency packed and we took T Red line > south station > lucky star bus to NYC (11:30 pm) … arrive around 4 am and take J nyc metro to JFK airport.

derp! didn’t get on flight seattle > narita, (yay standby) due to some weight balancing fail. (flight left with 34 empty seats)

that’s okay, we got to meet cathy’s family! (cathywu.posterous.com)

well got on next day

ack! have to get on flight narita > taiwan now.

[edit: for more updates on vending machine, see: http://www.orangenarwhals.com/search/label/vendingmachine]

Nyancat cake mold, working PoV [not so yoyo], vending corkscrew test (mod servo for continuous rotation)

nyancake
Uhh I’ve been doing a lot of blogging and neglecting my other work, so here is minimalist style ftw.

nyancake? nyangummi?

My hall’s thanksgiving (putzgiving, alums come back for this) was two Saturdays ago. I tested out the nyancat cake mold:

for ease of “parameter optimization” runs, I used even-simpler-cake-recipe: cake mix and sprite as the only ingredients (apparently a dieting trick. comes out fine, although for molds probably want to let bubbles settle for a bit after pouring and before intensive mixing).
apply release agent, aka cooking spray / pam — otherwise doesn’t come out well. also,  sprite+cakemix mixture should not be too gloopy. add flour if accidentally pour too much sprite.

many fail results. Here, did not let bake long enough. (much longer than box says — I baked a bit lower temp based on silicone mold research, ~325deg C, and for say 1 or 2 hours)
demolded too quickly, also did not cover in saran wrap to retain moisture afterward
nyancake party~! nyan nyan nyan
probably the best of all my nyancakes. you can see that the minimum mold feature size — the sprinkles — were too small for the resolution of the cake mix and actually resulted in holes.
speed cooling jello in freezer. recipe used: the lego gummies from instructables
nyanjello = almost perfect mold replica. you can see the sprinkles are supposed to stand out, as opposed to how the nyancakes turned out. however, more limited / difficult coloring opportunities with jello than with cake (which you can just apply frosting / food coloring to)
Persistence of Vision Yoyo
I also figured out the issue with the MAS.863 makefiles causing my weird “compiler” bug (actually, compiler options / makefile bug):

Class-based makefile includes:
avr-objcopy -j .text -O ihex ./v0.1.45.out ./v0.1.45.c.hex
man avr-objcopy
       -j sectionname
       –only-section=sectionname
  Copy only the named section from the input file to the output file.
  This option may  be  given more than once.  Note that using this
  option inappropriately may make the output file unusable. >__> <__<
So the class makefiles should be fixed to include “-j .data”The internet says
“The makefile above DOES NOT create a proper HEX image and is a bad example. When creating an  image, not only does the text section (which holds the code) need to be included but the data section (which holds any initialized data) also needs to be included.
The remedy for this is correct .hex rule to to copy the data setion as well
Example:
$(OBJCOPY) -j .text -j .data -O ihex $(PROJECT).out $(PROJECT).hex
http://www.micahcarrick.com/avr-tutorial-digital-output.html

bmayton: that actually explains a lot of odd bugs that I’ve been seeing with people

using constant arrays, since the array data is never getting copied into the
program

So the actual model of what was causing my bug was, I believe, without calling another function the compiler goes ahead and uses the array to insert the correct commands into the compiled code. But when I used a subfunction, the compiler loads the subfunction which the microcontroller calls, but the ucontroller does not have the array data to look up what to set DDRB and PORTB to.

Anyway, then I proceeded to hack together terrible!code and get PoV working. I used oloepede’s sample image ‘cos I’m all about the laziest and quickest tests and ‘cos olopede is awesome.

eheh derp ripped off ISP traces / headers
works fine waving it by hand (without camera extended exposure time, hard to see entire “olopede” message — can see maybe three letters at a time. dead reckoning PoV timing — no sensors.) 

Doesn’t do so hot on the drill. Mess with timing? Although I spun it slow and fast (and in-use yoyo spins quite fast). May require sensors (fan pov as seen on dealextreme — product designer has better idea of speed of motor while yoyo has more variable speed. maybe they used hall effect sensors, ‘cos it was resilient to me slowing down the blades.) to get stable image.

See video:
https://picasaweb.google.com/113942194695013581888/PoVYoyoPersistenceOfVision#5681157457783660930

Vending machine
Right, essentially two weeks until final projects due. Aka time to start cramming on vending machine.

What do I have on hand? Arduino uno, extra servos leftover from when I bought out all the old 2.007 servos., zipties, handheld drill, a corkscrew. Found some rectangular metal thing to act as guiderails lying around MITERS scrap pile. Also found a block of wood lying around the floor.

Mod a servo  to be
continuous rotation servo
(essentially turn it into a cheap RC motor that comes with motor speed controller in a convenient package for mounting) —
aka remove mechanical stop on gear 

apply flush cutters to stop on gear

and remove pot, which like all pots doesn’t turn infinitely — make sure to be gentle ‘cos pot is held in by internal screw, why it doesn’t just fall out normally

see blurry screw at bottom. Also, I wasn’t gentle and cracked the PCB. Maybe it is inevitable for these servos (motor is soldered onto pcb so not much flexibility there) to get to pot screw. Surprisingly the servo still works…
stick pot on outside, chew a hole for it in the casing — i abused flush cutters

see How to Hack a Servo by Daniela Faas http://stellar.mit.edu/S/course/2/sp11/2.007/courseMaterial/topics/topic12/other/Servo_Hack_large/Servo_Hack_large.pdf)

springs / coils
Attach to corkscrew (from real vending machine) I bought off of ebay to see what real mass manufactured ones are like so I can make fake ones DIY like http://www.instructables.com/id/Make-your-own-springs-in-seconds/

Drill out servo horns (1/8” bit fits zipties I found) and attach to corkscrew with zipties

it vends a block! haha. terrible setup is terrible.

Video here:
https://picasaweb.google.com/113942194695013581888/VendingMachineOpenHardware#5681154916854562050

Yea, not a very interesting proof-of-concept (a “duh are you an idiot” one), but it was very satisfying to me.

Oh right, I tried to use hot glue to hold the pot in one place, since that affects how the servo reacts to servo.write() (pot adjusts when it goes fwd/reverse) — I just used
myServo.write(50) with a 0.5 sec delay
myServo.write(90) with a 3 sec delay
myServo.write(130) with a 0.5 sec delay
to calibrate the pot so that servo was completely still at 90. And then attempted to hot glue. a bit flaky– not good enough for long-term banging around but good enough for dirty proto.

yes, i stole arduino from hexarideablepod. arduino uno with a small breadboard on top and 3 male header pins to connect arduino (Vcc, Gnd, and SIG — arbitrarily pin 2 in my case) and servo. unplugged in this pic.

Not clear from pics, but to test it I’m holding the servo still with my hand.

todo, DIY vending machine (countertop and oshw)

Like this, but with arduinos. and caffeine. and breadboards. and 1/64” drill bits. and nyancat-etched poptarts. Oh, and open source. And constructable for less than $600.

(I get to the whole build-my-own vending machine thing further down the page. Got a bit ADD).

Well, in other news, my 2.008 group did not fall over themselves to build a PoV yoyo. This is okay. I will just make one or two PoV (persistence of vision) yoyo’s manually then. (you, dear reader, have just been saved from a pages-long rant as I sulked over the last few days :P)

In other news, in MAS.863, it’s waterjet and shopbot week! I’m super-excited.

<3 3-axis mill. Shopbot r awesome~

(look, someone made a giant scrabble set using the media lab shopbot:

http://mako.cc/copyrighteous/20110725-00

)
Mini projects this week:

[1] Shelving. make this (playatech’s plans — rec’d by fellow classmate novysan, who had fun with these at burning man. also rec’d “nomadic architecture” which sadly did not mean nomadic furniture like Walking Hexapod Racing Chair but rather furniture suited for nomadic humans)

http://www.playatech.com/index.php?deptName=03Bare%20Necessities&prodDesc=09Gear%20Gizmo

(aka shelving made from one sheet of $8 7/16” OSB plywood,

http://www.homedepot.com/h_d1/N-5yc1v/R-100091344/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053)

Artsy furniture (metal): http://dornob.com/open-source-free-flat-pack-plans-for-laser-cut-furniture/
Styrofoam furniture: http://dornob.com/laser-cut-styrofoam-seats-solid-3d-polystyrene-chair-design/

[2]  I have lots of marble leftover from our clock class, which some people took proper advantage of while I merely used lasercutter and acrylic:

classmate’s AWESOME marble koi fish clock

mmm, instant noodles. aww. I miss my old room.

Oh right, where was I?

Arduino vending machines. That’s right. Make a DIY “open-source hardware” vending machine. Not interested in the electronics of accepting money and such (although that’s what everybody leaps to help with that, despite me explicitly stating I’m more interested in the vending mechanism).

Research:
http://en.wikipedia.org/wiki/Vending_machine#Mechanism
www.discapa.com/eng/download/manualt/MTMacSpiralE — coin mechanism and spiral set? not sure what it vended
http://www.vending.com/vending_machines/combination_vending_machines/combo/manual/
So they’re called “augers.”

from: http://www.vending.com/vending_machines/combination_vending_machines/combo/manual/

Found! mcmaster-carr “Dry goods screw conveyors”

http://www.mcmaster.com/#auger-conveyors/=ecttus

 ?!?!?! $677 is the cheapest one?! holy shiznatz that is out of the question.

Smexy pdf images: http://www.screwconveyors.com/profile2006x.pdf
mmm online worksheet AND considerations pdf:  http://www.kwsmfg.com/products/Screw-Conveyors.htm, http://www.kwsmfg.com/pdf/KWS-0709PBE.pdf . So I want “shaftless screw conveyor”
Ewww, this just ‘cos it has a pic of a screw conveyor used in a slaughterhouse: http://drycake.com/equipment/screening/downloads/Screening_Catalogue.pdf
Making Things Talk mentions it briefly… I wonder where I get a “big screw” (via libproxy.mit.edu): http://proquest.safaribooksonline.com/book/hobbies/9780596510510/chapter-9dot-identification/301?reader=pf&readerfullscreen=&readerleftmenu=1

Interesting tidbits about vending machine locks: http://books.google.com/books?id=6tRcZtGADBcC&lpg=PA142&ots=KBqWOPS2Jk&dq=vending%20machine%20screw%20mechanism&pg=PA143#v=onepage&q=vending%20machine%20screw%20mechanism&f=false