Engineering Overkill Motorizes The Daily Grind

You don’t tug on Superman’s cape, and you don’t come between an engineer and his coffee. And really, if all your office has for coffee is a big old BUNN that makes caffeinated trash, you don’t discourage your coworkers from the pursuit of a better brew.

[George] is over at his desk each day treating coffee like the science experiment it is: with a kettle, a Chemex, and a manual coffee grinder. Trouble is, the setup is attracting more and more attention, and [George]’s unpaid side gig as the office barista is starting to wear out his arm. He considered buying an electric grinder just long enough to laugh at the idea, and then went out to the workshop and built this beautifully over-engineered motorized mount for his manual grinder.

The only trouble with motorizing these hand grinders or even driving them with a drill is that many of them have a pentagonal shaft. But that problem was no match for [George] and his file. He soon had his linkage between the 100RPM motor and the grinder shaft and set about building the overly adequate frame.

The whole thing is gorgeous, but we particularly like the gas spring that holds the motor up out of the way while he pours in the beans. [George] probably ought to start a bean fund, if he hasn’t already. That kind of noise followed by the smell of coffee is bound to bring a few more fresh-ground converts into the fold. Grab a fresh cup and grind past the break to see this baby pulverize some beanage.

Not everyone goes for pour over coffee, but there are hacks to be done at all points on the coffee spectrum. Check out [Maya Posch]’s adventures in totally tweaking an espresso machine.

26 thoughts on “Engineering Overkill Motorizes The Daily Grind

    1. A “hot water dispenser” seems to be the generic term for them. They’re also called “instant kettles”.
      However, that one looks like it’s on some custom mount, don’t know if that’s just to raise it up for the chemex, or if it’s been removed from a drip coffee machine.

  1. Beautifully done! Unfortunately, if that manual grinder is anything like the one I had (it looks pretty similar), the pentagonal shaft is likely to round off fairly fast, even without motorising it.
    Thankfully mine went before I’d put any effort into motorising it. I replaced mine with a purpose-built electric grinder.

    1. I future proofed my setup, the 3 jaw chuck on my drill clamps pentagonal shafts and round shafts adequately so when it does eventually round off (which may happen sooner rather than later as I occasionally forget to turn off hammer mode) I don’t need to change the process.

    2. The reason they do this is because chucking the drive into a drill is the first thing everyone with a manual grinder tries. They don’t want you to do this, because basically all manual grinders are using cheap bearings (or more likely, bushings) suitable for low speed and low axial loads. Hook a motor up to it and now you’re very likely to be grinding plastic bushing shavings into your coffee.

      Neat hack, but horrible idea, particularly when good-enough burr grinders with a motor (and suitable bearings) can be had for under $100.

      1. Yes, my hand grinder had bushings not bearings. I quickly realised my drill was going to be way too fast – even if the grinder survives, if you grind too fast it gets hot, and that damages the coffee.
        My coffee supplier at the time recommended a delonghi grinder which was regularly on discount (to ~£50) and gives a reasonably consistent grind. It can be hacked to do expresso, though I’ve not got an expresso machine.
        It’s not the best grinder, but it’s not the weak link in my coffee-making, and there’s no point in spending more on a grinder unless I improve the rest of my process.

  2. Don’t knock the BUNN, it’s only one part of the process, you need a good bean, you need the proper grind, you need to have good water, and you need that water to be at least 181 degrees (unless you prefer cold brew).

  3. Again but on topic. A Melita filter cone with paper filter and a former wire screen holder based coffee maker drips (need to check temp) water into the cone. It’s a Black and Decker home cafe model, no drill here though. It was free from the curb. Pushbutton easy single cup perfection. The kitchen counter doesn’t look like a science lab or hacker space. Seven stage RO filtered water is put into the B&D heater’s tank, this was a major improvement! The water maters. Fresh grind is from a mid century Kitchen Aid electric grinder set to fine, they still make them though. Not much of a hack but all in all great coffee!

    1. Just using water from one of those cartridge jug filters like a Brita can make a huge difference. Also filtration, fine grinds need the good filter or all the dusty stuff makes it muddy. You can buy the cheaper filters with a medium grind that doesn’t come out too dusty. If you have a large basket on the drip machine and it doesn’t run too fast, you can try doubling up the cheapo filters, which I think is still cheaper than the name brand ones.

  4. so after seeing this I took my ever faithful Japanese stainless steel and ceramic coffee grinder and chucked the pentagonal shaft right into my dewalt cordless drill. grabs pretty solid without any work. Might do a 3d printed adapter tho.
    why cordless? because this thing is my off grid coffee grinder! as long as I got beans, and sunlight, I can power grind my solar powered camping battery bank and then feed the drill battery charger lol.
    Almost anyone can overengineer. The real trick is overengineering after the apocalyptic crash of infrastructure! (All I need is to get all the local w33d growers to set up some coffee plants in their hydro setups, I already know someone with an off grid capable coffee roaster, and I’ll be the King around here :)

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