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Coffee roasting with a Raspberry Pi and a popcorn popper

One of the easiest ways to improve the taste of coffee is to use freshly roasted beans. You can roast your own coffee at home using a variety of methods: the oven, a heat gun, or a air popcorn popper. One of the main difficulties with these methods is getting consistent and repeatable roasts each time.

I used an unmodified West Bend Air Poppery II popcorn popper for a few months but was not very impressed with the results. The popper ran at too hot of a temperature and burnt the outside of the beans before the inside was roasted. Also I had to visually watch the beans and decide when to turn the popcorn popper off to stop the roast. The roasts yielded coffee that was drinkable but left a lot of room for improvement.

I modified the popcorn popper so that I could control the temperature profile of the roast. The current coffee roasting setup uses a Raspberry Pi, a thermocouple, and the previous popcorn popper to enable greater control over the roasting temperature and much improved repeatability. I’ve been using this setup for about 1.5 years and have been very happy with the roasted coffee.

Below is a list of the materials and components that I used to build the roaster. I’ve tried to provide links to where these items can be purchased but keep in mind that the links aren’t necessarily the exact product that I used.

Materials and components:

Using the prices listed above the total cost is around $225 not including shipping or taxes. Many of these items you likely already have though and I also encourage you to shop around for better prices. Below are a few pictures of my roasting setup. If you have any questions let me know in the comments.

Assembled coffee roaster.
Assembled coffee roaster.
Sweet Maria
Sweet Maria
Sweet Maria
I use about 100 grams of green coffee per batch.

One Comment

  1. Joshua Thomas
    Joshua Thomas 2018-03-28

    This is super cool. How are you using the raspberry pi? Is it connected to a computer program to control the temperature?

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