Homebrew Keg Scale / Monitor [for Arduino Uno]

prusaprinters

<p>Homebrewing beer is something we do pretty often around my place for fun. I was tired of guessing how much beer was left in the kegs in my keezer (so I could plan our next brew day, of course).</p> <p>So, I whipped up this simple keg monitoring system to run off of an Arduino. I even programmed my Arduino to run on two kegs and to display a sad face <code>:(</code> in the event that a keg is low! It really consists of</p> <ol> <li>a display case to hold the display and electronics</li> <li>a load-cell sensing platform upon which to place the kegs and weigh them</li> <li>an optional bracket to add a simple corner-mounted computer fan to circulate cold air within the keezer. </li> </ol> <p>Basically the Arduino just keeps receiving data from the load cells, compares the observed weight to the known weight of empty and full kegs, and it shows the percentage of liquid remaining in the keg. Easy!</p> <p>It's a bit of work, but worth it to me in the long run.</p> <h3>Print instructions</h3><p><strong>Printing</strong></p> <p>Fortunately, there are no real need for printing instructions. I printed everything on my MK3/S in Prusament Carmine Red PETG with default settings. Everything came out just fine. Basically you'll need to print</p> <ul> <li>a display housing</li> <li>a display housing bracket</li> <li>a weighing surface per keg</li> <li>4 load sensor holders per keg </li> <li>1 load cell amplifier per keg </li> <li>a fan bracket if you want one</li> </ul> <p><strong>Necessary parts</strong></p> <ul> <li>An Arduino Uno</li> <li>Standard display</li> <li>4 load cells per keg (I used 50KG load cell half-bridge load cells) </li> <li>1 load cell amplifier per keg (I used HX711 load cells)</li> <li>Wiring stuff (wire, soldering iron, solder, heat shrink, etc.)</li> <li>Glue</li> <li>Some M3 bolts/hardware</li> <li>Some wood screws</li> <li>(optional) 80mm 5V fan</li> </ul> <hr/> <p><strong>Assembly</strong></p> <p>I'm sure this is going to be very user-specific, but I'll just share what I did.</p> <h3><strong>Scale</strong></h3> <p>I attached the load cells to the load sensor holders and then glued the holders to the load sensor platform. <em>(Optional: I ran everything through some nice braiding to keep all the wired together and organized.)</em> I soldered the load cells to the HX711 load cell amplifiers according to the wiring diagrams that came with the amplifiers and load cells. Then push the bundle of wires into the channel on the load cell platform, push some zip-ties through the holes, and tighten to keep them in place.</p> <p><em>Note that the scales are designed to fit "directly" with the bottom of Cornelius kegs, so you may want to do some smaller test prints to make sure they fit yours. I have four different brands and they all fit this.</em></p> <h3><strong>Display</strong></h3> <p>It will help if you check out the images, there's only "one way" this can go together. I mounted the LCD display and the Arduino into the display housing with M3 bolts. I wired the display to the Arduino, and then I attached the HX711s to the display housing (see the attached pictures). I wired up the HX711s, and while I was in there I ran 5V power from the Arduino to my 80mm fan.</p> <h3><strong>Fan Bracket</strong></h3> <p>I attached the fan to the bracket using the desired hardware.</p> <h3><strong>Final Physical Assembly</strong></h3> <p>I drilled a hole through the keezer's wooden collar and insulation that was just a big enough diameter to get wires through. I screwed the display housing bracket into the wooden collar with normal old wood screws. I placed the completed keg scales in the bottom of the keezer and tested fitment with the kegs. I then ran these wires up and along the sides of the keezer so it looked all nicey-nice (see pictures), and ran these wires out the hole to the Arduino. I screwed the fan bracket into the collar and I ran the power lines for the fan out the hole to the Arduino. Then, all that's left to do is plug the final bits and bobs into the Arduino and slide the display housing into its housing bracket. It should just be a nice friction fit. Power it up, flash your software, and your project is done. Enjoy.</p> <hr/> <p><strong>Software</strong></p> <p>I'll leave this up to the maker to get their own Arduino code put together since everyone has their own needs and implementation details. If there gets to be a lot of interest, I can help out or upload what I have somewhere. Really, though, it is quite simple. Display and HX711 drivers already exist for the Uno, it's just getting everything wired up and talking to each other.</p>