Alan Baker’s Bar Monkey

Pouring a drinkWhile I have written about the Bar Monkey I helped Alan build this winter it’s time to give a better overview of how the whole system works. This is not intended as a how-to but may be of help to folks who are looking to make their own Bar Monkey.

The Bar Monkey is a device for automatically mixing drinks. The concept comes from where you can see several other versions of bar monkeys. Almost all of Alan’s Bar Monkey, including the software, was designed by Alan.

How it works

To dispense a drink with the Bar Monkey all you have to do is place a glass under the tap and choose the drink you want from the display. Your drink is poured from the sixteen ingredients (13 liquors and 3 mixers) contained in the Bar Monkey, all you have to do is add ice and stir! If your drink requires something that didn’t make it into the Bar Monkey (we had trouble piping soda and decided milk products would probably go sour) the software will remind you to add it afterwards.

The Software

Pour a drink

The brains of the system is the Bar Monkey software. Alan wrote this custom Java application which, on startup, reads a text file with a list of drinks and ingredients.

The application has four screens for setup and controlling the Bar Monkey. The first and most important one is the “Pour Drinks” screen where just a single click can pour a complicated drink with up to sixteen ingredients. While the drinks are of different sizes any of them will fit into a standard pint glass with room for some ice. If you’re not sure if you’ll like a drink you can view the ingredients on screen or even use the “Taste Test” option which will pour a small drink, one quarter the size of the normal one, with exactly the same proportions.

The second screen will pour a 1.5 oz shot of any of the ingredients in the Bar Monkey. If your favorite drink is not in our list you can use the “Create Custom Drinks” screen to enter the amount of each ingredient for your drink. You can then pour the drink, or pour a “Taste Test” to try it and adjust ingredients if necessary.

The final screen is the “Priming/Cleaning” screen which allows you to control individual ingredients to clear air from the lines, backflow to empty the lines, or run a cleaner through.

Alan is continually updating the software and future features include drink pictures and the ability to save custom drinks. If you’re interested in the software you can contact me and I will pass your requests on to Alan.

Inside the Bar Monkey

ComputerThe software runs on a Windows PC which has been mounted in the Bar Monkey without a case. The PC controls a set of serial relays built from a kit. The kits can be purchased from

ValvesThe serial relay kit is used to control a series of 16 refrigerator water valves which run on 120 volt AC. These control the flow of each liquor to the tap. Since everything is live 120 volt Alan put together a Plexiglas shield to reduce the risk of electrocution.

C02 tankThe valves provide flow control but, just like in a refrigerator, something else needs to provide pressure. In Alan’s Bar Monkey the pressure comes from a five pound tank of CO2. The variable regulator on the tank regulates the pressure down to only 5 PSI and the valve coming off of the regulator provides easy shut off and converts the thread of the regulator to 1/4-inch outer diameter polyethylene tube. This tubing is the standard for hooking up water to a refrigerator and is available along with a wide variety of splitters, valves, and couplers at home improvement stores.

If you’re considering building your own Bar Monkey I suggest starting with the pressure system. Finding a size and style of tank that fits right and can be refilled locally, then matching it up with a regulator and converters proved to be quite a challenge. Pay special attention to the thread (right-hand or left-hand) of all connections to make sure it will go together in the end.

SplittersIn order to pressurize all 16 bottles the pressure line must be split. While I’m sure there is a more elegant way to handle this, we used T-splitters to make one end into two. It took quite a few splitters but they do not seem to leak. We also added valves to be able to shut off each side independently for easy refills. All the splitters and valves are a quick-connect type which allows the tubing to be removed easily to clean and reroute tubing.

capWe chose to use two liter soda bottles to hold all the liquors. Two liter bottles are surprisingly strong, cheap, common, and all have a standard cap. The bottles, caps and lines are all marked with painter’s tape to assure the right bottle goes on the right line.

capThe caps, which we thought would be easy, turned out to be the biggest challenge of the project. The caps, and the tubes which are glued into them, are made of polyethylene. The molecular bond of polyethylene is so strong it is almost impossible to glue. After several failed attempts with hot glue, cyanoacrylate, silicone and epoxy we finally landed on a solution.

This may sound a bit extreme, but in order to glue polyethylene you must “flash” it first… with a propane torch! By just touching the polyethylene with the blue inner flame of a torch it changes the molecular bond (this is a chemical change, not melting) in a way that it will take glue. We actually found this tip in an Old Town kayak repair manual.

The first step to making the caps was to drill two 1/4 inch holes in the cap. The plastic insert usually falls out at this point, but its absence doesn’t seem to hurt anything. You can then insert the tube through the cap. The tube going to the tap should be long enough to nearly reach the bottom, the other just needs to go through far enough to be solid.

Next we flashed the tubing and caps and wrapped a piece of painter’s tape around it to form a cup for the epoxy. At this point we put the cap on a half full bottle to keep it upright and poured enough epoxy to get a good thick layer. We used 30 minute epoxy but faster epoxy would probably work as well. Once the epoxy had a couple hours to set up the caps were ready to go.

The line which runs to the bottom of the bottle is run up to the valve array. Here wire ties and coaxial cable tack-downs were useful to keep things organized. As seen above, the valves were mounted on three boards to make them easier to install.

The tube coming out of each valve runs all the way to the output of the tap. That is why you can see separate colors on some of the pictures. The tap itself is half of a standard sink trap. Running all 16 tubes around the bend of the tap takes a little fidgeting but is possible.

The full monkeyThe housing of the Bar Monkey was an inexpensive computer cabinet from a popular box store. A hole was drilled in the top for the tap and plywood was used as a substitute for the cardboard backing that came with it. The handles were also replaced to dress it up a bit.

Final Thoughts

Alan, and those of us who helped him, learned a lot on this project. The whole thing took probably around 200 man hours to complete. We have not calculated the total cost, but if you were looking to build one of these yourself you should expect to be into it for up to $1,500 or possibly more depending on how much you can scrounge. I also wouldn’t recommend this as a project for anyone who is not comfortable working with household current.

project, diy, drinking, drinks, entertaining, bar, mixed drinks, bar monkey

10 thoughts on “Alan Baker’s Bar Monkey”

  1. Jack wrote:

    My name is Jack, and I’ve been toying around with some ideas for my own
    barmonkey over the past few weeks. Since there’s not much activity of
    the forums, I’ve sorta been lurking around and reading up
    on things, coming up with my own ideas, etc. I’ve decided to develop a
    small, portable drink making computerized machine inside of a computer
    ATX case. My friend is helping me a little bit, and suggested we call it
    the Drinkputer. I’m even doing an LCD screen case mod so that I don’t
    have to lug around a monitor. 😀

    I’ve got hardware, I bought an assembled K108A serial relay, I got some
    windshield washer pumps from and even got two Flojet C02
    pumps from ebay for like $30. I’m started to put it all together. But
    the problem for me is the software. I know hardware, and have a limited
    amount of electronics knowledge, but programming is totally not my
    thing. So I’m planning on trying a few of the programs I found on once I get everything put together over the next week or
    so. If possible, I’d love to try out Alan’s software.

    Anyway, just wanted to throw all that out there. Gotta go to a meeting.
    Heheh. Cya!


    and I replied:

    Sounds cool Jack. I like the name, as long as it doesn’t make you into a drinkpuker…

    I’ll pass on your request for the software to Alan.

    I’m guessing you’re going to have the bottles external to the ATX case right? It could get a bit crowded in there as well (not to mention warm up the liquor and boil off all the alcohol.) Sounds like you’ve got a good start to things. Good luck!


  2. Alz, looks like you’re onto something. Using a microcontroller will help keep the production cost down if this goes to market.

    It seems like you have a reasonable budget, a good plan, and a good team. Best of luck to you, and I hope to hear how this comes out!


  3. No how-to David. Alan did a lot of digging in forums and we did quite a bit of improvisation to make everything work out. Even still we have some problems with running Orange Juice through the valves.

    My advice is to involve a few of your more clever friends and don’t be afraid to improvise. My only warning is that the budget can easily get out of control on this project, especially if you’re in a hurry.

    It’s a great project, but because not all parts are going to be available everywhere it would be very difficult to write a true how-to.

    Sorry I can’t be more helpful. Good luck.

  4. If you don’t mind me asking, what exactly was the problem with the soda? Does its carbonation pose a problem for piping it? I had previously thought that soda would be a non issue with a CO2 system based on how well a kegerator works.

    I am starting to seriously consider building a small scale bar monkey, and have been reading everything I can on it. However, I would really like mine to work with soda / tonic.

  5. Terry,

    Soda frothed up and overflowed the glass coming out of the bar monkey.
    I think kegs and fountain soda work at a much higher pressure (our
    monkey only uses a few PSI) and the valves are right at the end of the
    tubing where as our monkey has quite a bit of tube after the valve.

    If you find a way to make it work please do share.

    Good luck. It’s a fun project.

  6. hi, i am a girl who actually doesn’t think your bar monkey is stupid!!! i actually think it is pretty cool. i am thinking of making one my self but i dont really have the time, anyway, just wanted to tell you how cool your idea is talk 2 u later!!!

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