|Click on image above to go to PDF file|
|Rendering of partially designed board (top view)|
I’ve been learning circuit board design and component selection. I’m hoping to not only simplify the entire wiring design for my cold brewer. I’m trying to expand its capabilities tenfold.
So I’ve completed my design. I’ve converted my 3d printable files to STL files and have sent them off to the printer: www.3dhubs.com. fingers crossed that everything comes back nice … you never know with these types of “compact” housings… Plus this is my first functional 3d print … Everything else I’ve done in the past was not as critical.
With this initial beta release, I can control my coffee maker from anywhere. I can check the progress of how it is doing. and I can adjust the flavor profile depending on how many drops per minute (DPM) & grind type I use. And I can know that it is always exactly where I want it because it’s a closed loop system with constant feedback.
- real-time drip-rate monitoring
- drip rate selection using micro servo
- fully functional wifi-enabled controller (hackable arduino) files shared on Github …
- LiPO 850mAh battery for anywhere brewing
- 5VDC battery charger (micro-USB same as your phone)
- fully customizable monitoring display (it’s your phone) Server & app run by Blynk
- use any of your favorite glasses or mugs.
- industrial pipe design
- (planned feature) ETA
- (planned feature) battery monitor
Oh, and also, since my idea is to eventually release this into the world with huge potential for modifications and improvements, I’ve shared my code on my GitHUB. Feel free to make improvements. make comments, or even suggestions that I can implement (note, I’m not a software guy … I juts do this for fun. So go easy on my code).
So its been longer than I’d have hoped for this post, but I was so torn in my design ideas that I decided to wait a little. I let the ideas settle in my mind and eventually, the inspiration came!
I had a few design criteria to make this Cold Drip coffee maker:
- Simple & Elegant
- Easy to manufacture with many “off the shelf” components
- Not offensive to Jenn’s Eye (The wife) … so It can be kept in the kitchen
- Has a certain “Bobby Style“
- Not too expensive (I’ll probably optimize this later)
|Cold Drip Coffee Maker – “Closed Loop Drop-BOB V1.0” (**Name is a work in progress)|
|V0.1 – the proof of concept|
|V0.2 – functional prototype|
|V0.5 – New and improved looks|
It was so good to see this familiar coffee colour (Canadian spelling eh). And since I started making smaller batches, I was able to minimize waste. It takes the same amount of grounds to make 2 shots of extra delicious cold drip, as it does to make 2 shots from an espresso maker … This is for those who think Cold Drip costs more on grounds … not necessarily.
So back to the glass cutting part. This is the part of the design that forced me to re-think my ways … At first I wanted to make my own water reservoir because I couldn’t find anything on the market that would work with a drip valve (open at the bottom & the top). I also wanted to potentially control the temperature with a peltier plate … but that will be for a later version.
I eventually came to the conclusion that I should modify a container to suit my purpose. Diamond tip glass cutting bits are a little expensive (but who am I kidding … I love buy new tools).
I did the entire cut on my drill press, with the glass inside another glass filled with water. Make sure you have no air bubbles.
The hole came out nice. Only a few little chips were missing, but nothing I can’t deal with by using some washers and O-rings.
This part was the most tricky … and the reason I spent over a hour standing in front of the brass fittings part of the local hope depot store.
Turns out that compression fittings are not easy to combine with other types of fitting .. like MIP, and Pipe treads, etc … I needed some distance between my valve and the glass ,so I can add my little beauty of a “Close Loop” servo control box (more on this later) … You see, the next great idea I had was not to connect anything other than a single hole to the bottom of a glass (or, steel, or wood, or coconut, etc). This allows me to use virtually any container that I can make a 3/8″ hole at the bottom.
Next step will be to upgrade the soda bottle to a glass bottle … but for me to do that, I’ll need a few new tools:
– Glass scoring bit mounted to score a bottle around its base
– diamond dremel bit … to drill small holes in glass
I may also work on a 3d printed structure to hold the servo & photo-interupter.
For now, I look forward to cold drip coffee tomorrow with the famillia. Happy family day.
So as my list of tasks for the week dwindled (now complete, save for side tables), I started my cold brew design with a good old trip to home depot (just to see what they have). It turns out that they have pretty much everything I needed to get started on my proof of concept.
Now, I know this “cold coffee” shit has been done many times. So why a proof of concept? Well from what I read online, Its an “unstable design”. You can’t really get the dripping just right … and even when you do … an hour later, it will be either no longer dripping, or dripping too fast.
So, I decided to start with the basics. Here is my home depot parts list:
Now, lessons learned. Since the wine bottle at the top does not let air back in, the air must come up from the tube … which it does, but not as predictably as I’d hoped. The result is an erratic drip, that needs to be adjusted every few hours. At the end I opened up both valves all the way … it still only dripped a little due to the back flow of air.
So I don’t like the original design … even though it made great coffee.
So today, I took apart an old Halloween Costume from 2011 to make my second “more commonly seen” version of the cold drip coffee maker.
I mostly just wanted to test out a system with no back-flow of air and I wanted to see the adjust-ability and repeat-ability of the 1/4″ needle valve.
So far, I’ve tried as slow as 11 drops/min and it stopped functioning after about 1-hr … (sticktion maybe?) So, I’ve increased it to about 40 dpm.
What I am working towards is a design that I can accurately control the flow (needle valve or Solenoid valve? … maybe even servo controlled needle valve). I’ve toyed with the idea of using a servo controlled valve but I think that would be too noisy.
I’m leaning towards a closed loop servo controlled needle valve (via arduino) with piezo electric drop detection (via sound). This has not yet been attempted by the internet (by my searching).
Once I can get this part working I will try to also control the pressure & oxygen content using NO2 cartridges. Not sure how I would fabricate a container for that though … food for thought.