Introduction: Robotic Drink Mixer

It's time to head back to college and that means lots of fun, parties, and EPIC TAILGATING!  (Go Razorbacks!)


This is a portable system that can mix over 5,000 drinks on demand from a laptop computer.  Build it and they will come!

Here is what the Robotic Drink Mixer is capable of:

Some of you may have seen my other instructable last year, BaR2D2, the mobile bar.  This is the long awaited drink mixer upgrade!  If you want to see the robot this can attach to, go here:

This system was built to replace the manual liquor carousel.  It has been an incredible upgrade and we have had a blast with it!

You can friend BaR2D2 on facebook:   bartwo dtwo

Step 1: Time to Order Parts!

The Robotic Drink Mixer uses a compressed air system to force liquids out of the ingredient bottles (air is forced into the bottles and a syphon tube allows the liquid to come out.  An electronic valve (solenoid valve) controls how much liquid comes out and when.

For my setup, I am using six ingredient bottles and six solenoid valves.  The bottles are about a liter each and have a standard neck thread like a plastic coke bottle (you can actually use plastic coke bottles).

The valves are 12 volt plunger-style solenoid valves (normally closed).  These were obtained at McMasterCarr for about $25 each.  I used part number #7877K313.  The air tanks are from ebay and were originally used in semi truck air horns.  You can use any air supply tank as long as it has enough volume to fully displace all the contents in your ingredient bottles.

I charge these tanks to about 75 psi and then using a regulator, reduce the pressure to 5 psi at the ingredient bottles. (any more than this is a get good flow at 5 psi and reduce air leaks).  Use a Schrader valve in your tank and then you can fill it using a regular air compressor or foot pump.  Use clear Tygon PVC tubing to connect everything on the low pressure side.  On the high pressure side, use pvc air line.

The regulator was purchased through SurplusCenter on the net for about $20.  I also got the gauges from there.  Again, you are basically just trying to get to about 5 psi at the bottles.

To make connections easier, I used acetal push-to-connect fittings. (McMaster Carr part #51055K14)  These thread into the valves and the Tygon tubing plugs into the fitting.  Size your tubing to match each connection.

To distribute the six air lines into the ingredient bottles, we used an aluminum manifold (McMasterCarr part #5469K151)  Thread your push to connect fittings into this as well.  The tops of the bottles that have the two air nipples were purchased through

Step 2: Make Templates for Structure

The parts for the drink mixer are made from 1/8" aluminum plate.  Mine were cutout using the waterjet process.  This machine uses a high pressure water stream with an abrasive compound to cut the parts.  I used the services offered by to cut my parts.  You simply upload a file to their site and they mail you parts.

Other materials (plastics, wood) can also be used.  If you don't want to go to the expense of waterjetting, you can use a jig saw or band saw to make your parts.

My templates were made to accomodate 6 plastic bottles that are about a liter each.  Your bottles may be different, so make your parts according to how many bottles/size of them.

You can see my finished template for the base, bottle support, and bottle holders.  Also there is the valve support and the compressed air tank supports.

Step 3: Assembly Time!

The parts are assembled with 4 threaded rods and nuts (I used 5/16").  These allow you to slide the parts on and adjust them all for proper clearances on everything.

I made a plate that holds the six valves.  Drill and screw the valves to the plate.

Cut the threaded rods to 4 equal lengths (length depending on your bottles and height of desired machine).  Also,  cut six threaded pieces to use to hold the upper supports together.

For the base of the portable system, I used an oval shaped plaque I purchased from Michael's craft store.  This was sprayed with black texture paint.  The base provides a stable base.

I attached the manifold, regulator, and valves to the base plate.  Your install may be different.

Plumb up all your airlines.

Step 4: Electrical Connections

Now that we have built the structure and mechanical bits, it's time to wire it up.  The brain of the robotic bartender is the Lazydrinker circuitboard. (  This board connects to a laptop via a serial cable.  The software was also obtained from lazydrinker.

Create a wiring harness for the valves.  They use a common ground.  The positive is run to a serial cable pin.  The pin designations are given via lazydrinker.

I also added 12 volt led lighting to accent the bot and provide light when my robot is running around in the dark at a party.

As for powering your Robotic Drink Mixer, you need a 12 volt power supply.  If you look around your shop or computer parts bin, you may find one from an old modem, computer, etc.  Just needs to have at least 1 amp (I would go with 4 if you can find one).

For BaR2D2's mobile usage, a custom Bluetooth receiver board was built (credit Jay Lueck).  This attaches to the lazydrinker board and allows wireless usage from my Dell PDA.

Step 5: Time to Party!

Now, fill up your ingredient bottles and pressurize the system.  You plug in your ingredients into the software and it generates a list of what you can make with them.  You are now in business!

A couple of usage notes - my system is designed for table top (or in my case also for mobile robot usage).  My items aren't refrigerated, but filled with cold ingredients, it will easily last all night.  If you want to use it again the next day, I would recommend putting the bottles in a cooler or refrigerator overnight.

Make sure to flush the system after each use or the valves will get clogged.  I recommend using bottle sanitizer used in home beer making.  Wash the bottles and flush the system and thoroughly dry everything so it will be good to go for your next party!

Have fun!....and of course the disclaimer:  drink responsibly, don't drink and drive, don't drink unless you are 21...blah, blah, blah.  Also, this is a pressurized system and MUST be treated with respect!  DO NOT build this system without a safety overpressure valve on your main tank!!! and do not fill them to more than the manufacturer's rated pressure.  Doing so creates an explosive situation!

You can see the full BaR2D2 robot in this video taken from a late night party in Atlanta a couple weekends back at Dragon*con.  It's always a blast to take it out!

Step 6:

Back to School Contest

Finalist in the
Back to School Contest