Hack together a Coffee Roaster

For most people, making coffee entails taking a couple scoops out of a can of pre-ground coffee, adding water, and pressing “Go” on the drip machine. To others coffee brewing is an artform, and want as much control over the process as possible. For those without an overflowing bank account for a home roasting machine, Evil Mad Scientist Labs have put together a general guide for throwing together a Coffee Bean Roaster and cooler (which is apparently just as important as roasting) from a low cost hot air popcorn popper. The home roasting scene is even big enough to warrant its own Wikipedia page, which also mentions using a popcorn popper as a bean roaster.

The guide includes some great simple circuit diagrams to keep in mind when hacking your own, as well as a good explanation why you shouldn’t just clip out the heating coil for cooling mode.


  1. kirov says:

    so snipping a wire or two to disable the heater counts as a hack now?

  2. James Munns says:


    I would recommend you read the article for what they really did, which includes replacing a poor rectifier bridge for a standard switching supply, as well as detail a number of tools for people to use independently; including both pictures, schematics, and links for purchasing materials.

    Generally whenever someone modifies a low cost tool to serve a purpose equal to a high dollar item, it is called a hack. When a good amount of documentation is provided, as well as this being a project that we think our readers would be interested in, we enjoy passing it on.

  3. Daley says:


    This has been discussed before:


    We can’t expect everyone to think like we do…

  4. kirov says:

    ok my mistake, not only did they snip a wire but they soldered a new one on.

    I think of hacks as modifying a device to do something unintended in a way that is not inherently obvious or in a clever fashion – I don’t think anyone with half a brain would have trouble modifying a popcorn maker to disable the heater.

    As for your other point, why not just link to that site directly?

  5. john personna says:

    Sounds excellent. I splurged on a Hearthware Precision roaster from Sweet Marias at one point. I don’t run it often, but now and then is fun. Note that Sweet Marias is a good source for beans:


  6. SPARCS says:

    this is a very pop-ular method in home roasting crew. Another is the “corretto” set up …using a paint stripper heat gun for the heat source and a bread maker for the agitation. with roasted costing from $40AU/kg and green beans @ $9AU/kg there is a great incentive to do this…it perhaps might not make a great deal of sense not to…esp if you like coffee.

  7. ClutchDude says:

    They didn’t say why, but what was keeping them from installing a DPDT switch for the fan and using one unit?

    It’d get its power from the 12V when one way, and from the rectifier from another.

    Does the whole unit just stay too hot to reuse after heating, thus needing a secondary cooling?

    Or does the heater assembly just restrict too much air flow?

    As an aside, this reminds me of a hair dryer. I wonder if those have a better fan assembly and might work!

  8. ClutchDude says:


    Ok…apparently STUPID me didn’t ready it closely enough on the first read thru.

    They had an extra unit laying around that sucked and desired to make it useful.

    I wonder if you could still use a single unit though.

  9. James Munns says:


    I had the same thought when I read through it, and if you look at the comments, they do address that, mostly you want to cool the beans to stop the cooking processes, but if it takes a couple minutes to get the whole machine back to room temp, the roast could be hard to predict.

  10. aztraph says:

    too bad coffee doesn’t pop like pop corn, that would be an awesome snack. of course just one popper, with a switch to disable the heater might work just as well and be simpler to just have one piece of equipment.

  11. gregw says:


    No need to comment on every submission. Just worry about posting your own hacks.

  12. ladz says:

    Coffee does pop! Not really like popcorn though.

    We’ve been roasting for a few months with a unmodified 1500W air popcorn popper. It works great. No modifications are really necessary. Unless I guess you wanted it to be more automatic or have finer roast control. But spending 20 minutes roasting a pound of coffee manually isn’t a chore, it’s fun and challenging to get the roast consistent by watching the smoke, smells, and sounds.

  13. Donovan says:

    You can also use this popcorn maker and just wire up a heating element pot and switch.


    You can adjust the temp and it will keep the coffee moving.

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