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Hey gents. I'm starting to look into building a fairly simple drink mixing machine. It's entirely a hobby proposition. If it works out I may give it to a friend that operates a restaurant serving thousands of mimosas every day .

My idea is fairly simple. A pair of "high" volume, rough measure feeds and a pair of "low" volume, precise measure feeds into a combining chamber. A slow agitator in the combining chamber. A second dispensing chamber that the combined liquid is drained into after mixing. Then a tap on the dispensing chamber for serving.

The four feeds should be sourced from vats with liquid level measurement. I can imagine the measurement valves and sensors being controlled by an AVR for real time accuracy. This controller would be interfaced with an ARM board running full OS that provides measurement data based on recipe input.

Possible additional goodies would be a refrigeration source for the dispensing vat. Realistically I'd like to build the AVR controlled measurement components first as a proof of concept.

Does anyone have any advice for sensor and valve hardware? I'm sure there are standard small-volume plumbing components I could adapt for this. I'm debating taking apart my k-cup machine to see how it's built.

Thoughts?

How do you keep the sparkle in the sparkling wine or Champagne part of the unit and in the dispensing chamber? if the mix is in there for more than a few min or two it will tend lose fizz). Is it kept under pressure? and design for easy and through cleaning.

Yes! The cleaning needs definitely occurred to me. As for keeping things fizzy, I've watched my bartender buddy make and serve from a new pitcher of mimosa every 20 minutes. No one seems to mind. Personally it's always seemed to me that brut and other sparkling beverages stay pretty fizzy for quite a while.

You are right and 20 min would seem to be ok for a standard level of volume production... but you might want to have some sort of warning timer to let the bartender know that what is in the dispense chamber is getting old (perhaps use it as top ups for the best customers?) When I worked as a bartender about 50 years ago it was at a fairly fancy joint and we were told to mix up enough for the current order if a large order that took a whole bottle of bubbly otherwise it was the standard to put up the champagne flutes fill half full with the wine then fill up to near top with the fresh squeezed OJ and then add the dash of Grand Marnier and garnish and serve.

Yeah one of the reasons I'm thinking an OS board for the recipe computer is the ease of implementing a fairly full featured UI.

When thinking about volumes, I'd see about a 2 litre container being ideal for mixing and storage. You could basically dump two bottles of bubbly in there plus orange concentrate and triple sec.

For this application you really do not need realtime. The operations are not that fast. Therefor I would HIGHLY recommend that you start with an arduino.

They have a small screen + arduino controller for 7 bucks on aliexpress.
http://www.aliexpress.com/item/Free-Shi ... 8.4.Dxu4Vj

I have done what you mentionned before many many years ago. My genius idea was to use standard pneumatic valves for air, but i had 2 openings on the bottles via modified caps. One would let air in, the other would be a hose to the mixing container.

When the air valve opens it lets air in to the bottle which leaks out some fluid (upside down) to the mixing reservoir. It is a bit more difficult to control but the major advantage is that, none of your valves etc touch the fluids and therefore do not need any cleaning.

Apart from that, you can use peristatic pumps to pump the liquids, these pumps basically work by "massaging" the outside of the hose to push the liquid along. With this configuration, you do not need much cleaning, make the hoses a disposable item and you are good to go.

http://www.aliexpress.com/item/Low-Pric ... .89.UnvyYn

The other nice things about peristaltic pumps are:
1. You can print the mechanism;
2. They can be used as a dosing pump. Given the size of the lobes on the pump, their location relative to the tube and thus the engaged stroke length on the tube, and the tube diameter you can determine the amount of fluid moved per stroke. Set it up right and 10 revolutions might give you a 30ml shot, etc.

If you could get one of these per ingredient and make a mixing tube - a tube with protrusions like vanes into it which create turbulence and thus mixing - you could possibly even set it up to push a button and mix the drink per serve rather than having it batched up in jugs.

A peristaltic pump mechanism driven by a stepper would be perfect. If printed, the mechanism should probably be in nylon so it doesn't go out of tolerance after awhile. (2nd choice PLA, 3rd choice ABS, based on the hardness of the plastic.) Make sure you buy tubing that's marked Food Grade.

To keep the drinks nice and cold, you can either use Peltiers, or phase-change cooling (like air conditioning). There are refrigerated PC cases that you could use for a chassis. The compressor is in the bottom of the case, and of course they have provisions to mount a 5 & 12V PSU, which would be convenient.

Peltier: Much easier to design a customized heat rejection system. Phase change-cooled cases have relatively fixed assumptions (your CPU is here, your graphics cards are there) that you'd have to work around. With Peltiers, you can site the "cold sides" of the system anywhere you want. You will need to use antifreeze, surfactants, biocidal agents, and possibly something else I'm forgetting, to make sure the tubes and water blocks don't turn into a science project. One idea might be to make a casque to hold a bottle of "feedstock," with copper tubing to run chilled water through wound around the inside in a helix, perhaps cemented in some copper compound (not RTV, but something designed to be conductive) to increase the rate of heat exchange. (You could just sit a Peltier at the bottom of the casque, but it would cool the bottom first and the top last, encouraging a temperature gradient.) The internal beverage containers would be removable. You'd clean them daily, and when you put them back into the casques, they'd fit snugly with the wall. The fluid running through the tubing would be routed to a waterblock (USE COPPER, NOT STEEL OR ALUMINUM). The waterblock would be sandwiched to the cold side of one or two high-wattage Peltier junctions, which should be potted with rubber cement in a low-humidity environment to prevent condensation from wrecking the junctions. On the hot side of the Peltiers, you'd have a large COPPER heatsink with a fan. If you use something other than copper, you'll only make it harder for the system to do its job.

Phase change: Harder to design, as you'd have to work with fixed assumptions, i.e. the CPU is here and the video cards are there. However, Puron, or whatever they replaced R42 with, is WAAAAY better at carrying heat than water, even if you add antifreeze and surfactants to it. These systems are professionally charged and sealed, so there's less risk that the coolant would leak. The tubing-in-a-casque system above might work if you use a Peltier to pump heat from the water into the cold side (evaporator) of the refrigerant system. In fact, it will take heat out of that system FAR more quickly than the air will take heat out of a heatsink/fan combination. There's also the question of whether the phase-change system lets you adjust the target temperature, and by how much.

For pumping, displacing the fluid with air, as suggested above, sounds like a good idea to me. You'd need to make sure to use something definitely capable of pumping air with a positive displacement (like a Roots supercharger) as it's necessary to precisely control the amount of fluid that's displaced. Air is harder to pump than liquid because it has so much less density. It might also be necessary to use barometric and heat sensors, so you know you're always pumping the same amount regardless of weather, altitude, and temperature.

The other (easier) way to do it would be to drop a tube into the bottom of the container and use a peristaltic pump on a stepper. You might be able to clean it by filling the internal tank with hot soapy water and telling the machine to drain the whole thing. You'd have to clean some parts of the machine daily anyhow, so this probably wouldn't be a big deal.

If you use water cooling in any fashion, wrap the nylon tubing with pipe wrap so you don't waste half the energy cooling the inside of the machine.

For filling cups of different diameters, you might be able to use an IR probe (like dc42's) or ultrasonic rangefinder (with sufficiently small minimum sensing distance) to ensure a consistent fill. With that, you could do the air-displacement system without having to worry about temp/barometric pressure.

I hope you do this, and show us the results!

I had my students do a plant waterin system with arduinos last year.

The system had to read the moisture in the soil, and monitor the water level in the reservoir.

And the cheapo arduino ultrasonic sensors (double barrel) did not work when placed on top of a 20L water container. Had to cut a hole in the side. I could not investigate why but i think it was because the sould was bouncing about too much and generating false readings.

Windshadow wrote:You are right and 20 min would seem to be ok for a standard level of volume production... but you might want to have some sort of warning timer to let the bartender know that what is in the dispense chamber is getting old (perhaps use it as top ups for the best customers?) When I worked as a bartender about 50 years ago it was at a fairly fancy joint and we were told to mix up enough for the current order if a large order that took a whole bottle of bubbly otherwise it was the standard to put up the champagne flutes fill half full with the wine then fill up to near top with the fresh squeezed OJ and then add the dash of Grand Marnier and garnish and serve.

Did they really have champagne 50 years ago?

HARUMPH!

Windshadow wrote:HARUMPH!

You knew I was kidding, I discussed with you about me being 64 years old. 3D printing does keep me going and this forum gives me a place to learn, a place to teach and
a place to have fun. Take care, my friend.

Governor William J. Le Petomane: [pointing to a member of his cabinet] I didn't get a "harrumph" out of that guy!
Hedley Lamarr: Give the Governor harrumph!
Politician: Harrumph!
Governor William J. Le Petomane: You watch your ass.

Windshadow wrote:Governor William J. Le Petomane: [pointing to a member of his cabinet] I didn't get a "harrumph" out of that guy!
Hedley Lamarr: Give the Governor harrumph!
Politician: Harrumph!
Governor William J. Le Petomane: You watch your ass.

Good One!

You must have picked the tamest four lines out of that entire movie

Well done.