Open Source Barbot Needs Only Two Motors

Most drinkbots are complicated—some intentionally so, others seemingly by design necessity. If you have a bunch of bottles of booze you still need a way to get it out of the bottles in a controlled fashion, usually through motorized pouring or pumping. Sometimes all thoe tubes and motors and wires looks really cool and sci fi. Still, there’s nothing wrong with a really clean design.

[Lukas Šidlauskas’s] Open Source Barbot project uses only two motors to actuate nine bottles using only a NEMA-17 stepper to move the tray down along the length of the console and a high-torque servo to trigger the Beaumont Metrix SL spirit measures. These barman’s bottle toppers dispense 50 ml when the button is pressed, making them (along with gravity) the perfect way to elegantly manage so many bottles. Drink selection takes place on an app, connected via Bluetooth to the Arduino Mega running the show.

The Barbot is an Open Source project with project files available from [Lukas]’s GitHub repository
and discussions taking place in a Slack group.

If it’s barbots you’re after, check out this Synergizer 4-drink barbot and the web-connected barbot we published a while back.

[via MAKE]

16 thoughts on “Open Source Barbot Needs Only Two Motors

  1. Hey, ‘r you drunk?! No? Then prove it!

    1. You have two glasses half full. One with Cola, the other with Vodka.
    2. Two clients are asking for two drinks. One with 1/3 vodka and 2/3 cola, the other one is asking for 2/3 vodka and 1/3 cola.
    3. There are no other recipients, only the two glasses.

    How do you prepare the requested drinks?
    Prove that any complementary alcohol drink’s concentration (e.g. 10% and 90%) can be prepared the same way.


    1. The solution must be to pour some of the vodka in the cola glass, and then pour the vodka-cola back into the vodka glass until the specified ratios are met. One would pour vodka into the cola glass until it contains the 1/3 mixture (1/4 of the glass), and then pour just enough back to the vodka glass until it contains the 2/3 mix.

      Since the vodka-cola now contains 1/3 vodka, the relative volume of additional vodka needed to reach 2/3 is three times the volume, therefore the 1/4 remaining in the vodka glass needs 1/12 of a glass of the vodka-cola mixture poured back.

      But this will not work in practice because the amount of vodka you’re allowed to sell in standardized into units. The client expects to get e.g. 4 or 6 cl of vodka in each drink regardless of the amount of cola mixer – the rules being made to stop bars from watering down their drinks. If you don’t have a standard and inspected measuring cup to dispense the vodka, the alcohol inspector will eventually come around and put you out of business.

      Additional troubles would come from the fact that a typical vodka tumbler glass is tapered and/or stepped, so judging the volume of drink being poured by eye without any other tools becomes an exercise in futility.

      1. It is also obvious that we don’t need to constrain ourselves to complementary ratios such as 1/3 and 2/3 or 10% and 90% because we can mix arbitrary amounts of the vodka-cola back to the vodka glass, and vice versa. In fact, we can produce any two ratios since the amount of drink in each glass is not specified.

        How? By chugging down some of either the vodka or the cola before we begin mixing.

      2. Correction: the amount of vodka-cola to be poured back is 1:1 with the amount of vodka remaining in the glass to reach 1/3 and 2/3 respectively. Therefore 1/4 of the vodka-cola glass must be poured back.

        (1/3 vodka + 1 vodka ) / 2 volume = 2/3 vodka/volume

    2. Who drinks vodka and cola?

      What kind of lousy bar is short on vodka, cola, and glassware?

      Pouring back and forth is going to take the fizz out, be sure to pour half of the vodka into the cola first to mitigate that problem. The cola glass is now 3/4 full of a 2/3 cola 1/3 vodka mix, pour 1/3 of that (1/4 of a glass) back into the vodka class. Serve to your customers apologetically.

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