• Espresso Brains

    Maxwell • 09/08/2026 at 18:42 • 0 comments

    Throughout the entirety of this project, hiatuses and all, I almost always kept the top of the espresso machine off, exposing the rats nest of blue and reddish-brown wires. Subconsciously, semi-consciously, and then finally fully consciously, I came to affectionally call it "espresso brains". I like it. I'm gonna keep it. Perhaps when the project is complete, I'll ask my brother to paint the top as a cartoony brain (he's the artistic one).

  • Flow Control

    Maxwell • 09/08/2026 at 18:14 • 0 comments

    I considered my first step to be taking the reins on the pump. Based on the shots I had pulled thus far, it seemed my flow was way out of control. I took the old AC dimmer approach by wiring my pump to power through a digitally controlled 8 amp AC leading-edge triac dimmer (RBDimmer from Robodyne, no longer available, but easily replaceable). I happened to have a number of Adafruit QT-Py boards (SAMD21 version) on hand, and have quite a soft spot for this little guy, so it was selected for the brains. More about the word brains in a later entry. I took the very basic approach of taking apart an old, but functioning, 5V USB wall adapter to wire up inside the machine and provide power to the board.

    I already had my Cycle library mostly written for a different project involving a motor that needed to carry out various phases of changing speed in the same way a washing machine might, so with some refinement I was ready to automate the pump with the dimmer. Initially, I used the popular PSM.Library from banoz (thank you very much banoz). I ended up finding the algorithm to be a little clunky for my taste, in terms of auditory experience. Hearing is certainly my most temperamental sense, so being disturbed by the sound of my machine when looking for my espresso session (espression) to be calm and soothing was a real concern for me. Not to mention I have a bit of a masochist-sisyphus complex. So I began searching for my own algorithm that would hopefully mathematically approach the requested values, ish, but sound more natural while doing it. The resulting library has limitations, but my ears said yes and it performs well for me. The banoz library was also helpful in demonstrating to me how in the world to write a library (thank you very much banoz). My libraries are linked in this project and published under Unlicense because nothing is my own, except legally.

    I saw success in ramping the pump up over the course of a few seconds (technically, a pre-infusion-sorta-thingy), then decreasing the pump utility from about 70% at the peak down to more like 50% over the next 10 seconds, then holding that value for the rest of the shot. No PID yet, just basic control. At this point, I was pretty happy with my machine and I just wanted to go back to drinking espresso, so I took a long hiatus from development. 

  • Purchase and Initial Repair

    Maxwell • 09/08/2026 at 01:38 • 0 comments

    The machine was purchased for $150 and appeared to be well-kept. The seller claimed regular maintenance and descaling was performed. He seemed confident the machine just needed a new pump, but it was not something he was interested in attempting.

    When I got the machine to my place, I confirmed that water was not flowing from the grouphead, though I wasn't convinced the pump had burned out as it seemed to be vibrating, or at least doing its best impression of vibration.

    When I first took off the top of the machine, it was a nightmare! The plate and electrical terminals had massive areas of rust and corrosion. Nonetheless, the electrical seemed to be operating just fine. Thank goodness for the simplicity of these old tanks and their lack of single-board computers... but then what was the actual issue with the machine?

    The internet told me it wasn't really worth trying to take apart or repair the old pump because they're so cheap and easy to find. I think that's dumb and also stupid. I disassembled the pump and it was absolutely full of gunk of all varieties. After some soaking, cleaning, and reassembling, it was running just fine. 

    While the pump was off, I took out the whole boiler plate. This is when I realized the leakage had most severely rusted the bottom of the plate, which was dropping large deposits of rust into the water tank below. This may have been a classic vicious cycle scenario. The high resistance of a gunked-up machine — perhaps accompanied by questionable attempts at maintenance the seller chose not to disclose — led to a leak, which lead to rust in the water tank, which led to a gunked-up-er machine!

    I scraped off every bit of rust and corrosion I could with brushes, flathead screw drivers, steel wool, and whatever else hard or abrasive I had on hand. I reinstalled everything and found that flow had graciously returned to me and my chrome stallion. Though the gifts brought by the flow were not nearly so gracious. After many, many tanks of flushing, the substance coming out of the grouphead finally began to resemble what I had put in the tank (water). Then I remembered the steam wand exists. Everyone, please. Please. Purge your steam wands. A few more flushes and we finally had ourselves an espresso machine right-ripe for modding.