Complete Tutorial - Modification of a Drum Air Fryer into an Artisan-controlled Coffee Roaster

Discuss roast levels and profiles for espresso, equipment for roasting coffee.

#1: Post by yokusan »

Dear HB members,

I invested a lot of time and effort in the last few weeks to film a video tutorial showing in detail the modification of an inexpensive Air Fryer with a drum into an Artisan-controlled Coffee roaster. I filmed this in german as it was for the mostly german community of (unfortunately some members have problems with english language). However, I tried to automatically generate some english subtitles, so english users might be able to follow the tutorial. Also, the sketch using an Arduino to simulate a TC4 modul for temperature reading combined with the ability to control the duty of an AC-powered heating lamp/element might be helpful for some projects here.

Here are the features of the roaster (I call it "BilloJoe"):

* Motor with 50rpm with enough torque for 250 grams of green beans (fits inside the Air Fryer without modification)

* Installation of shovels to ensure even roasting

* Modification of the drum axes to allow insertion of a thermocouple

* 1mm K-type Thermocouple 15cm goes through axis and detects temperature in the bean mass

* Arduino Nano with Thermocouple Module MAX6675, Bluetooth Module HC-05 and AC Light Dimmer Module (RobotDyn) on a small breadboard fits inside the Air Fryer/Roaster without modification below the motor, powered by 5V directly from the roaster circuits

* Control of the TRIAC on the PCB of the Air Fryer through the TRIAC of the RobotDyn Module

* Reading of Bean Temperature und Control of Heating Power via Artisan Roasting Software on Laptop (connected via Bluetooth with the roaster)

Here is the video (all links, files and a complete shopping list are in the Youtube video description):
And here is an exemplary profile from Artisan of a roast of 250 grams of Honduras green beans:

I would be happy if someone finds the time and to build another "BilloJoe". I am really convinced of its potential and I find that the resulting coffee has been fantastic.

I am aware that it seems to be difficult to purchase that specific Air Fryer (Klarstein Vitair Turbo) outside the European Union. However, I think that this modification might be possible also with similar Air Fryer that contain a rotating drum and a halogen heating lamp.

Happy modding and regards from Cologne (Germany),

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#2: Post by another_jim »

Thanks for posting this. These drum based air-fryers may be a better base for building a coffee roaster than a popcorn-popper or a bread-machine. In any case, this instruction video is pretty definitive.
Jim Schulman


#3: Post by pketiki »

Nice guide!!
I ll give it a try.

Just 2 questions:
1. What is the maximum temperature the beans can reach with this machine?
2. This machine - ... am=vitair- has a broader temperature range (30-250) and maybe a stronger fan? Do you think the modification still applies here?

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#4: Post by danetrainer »


Thanks for posting and indeed a quite clever adaptation of an air fryer to use as a coffee roaster. The poor English sub title translation severely limits the ability to follow the technical elements of the modifications.

I am very impressed that it is controlled via Bluetooth along with Artisan adjusting the halogen heating element for a declining profile.

The paddles you installed in the drum make for a very even roast by agitation of the bean mass.

I immediately thought of the Bullet roaster with your concept of others building a similar roaster as this and sharing profiles to help each other get the most out of a specific bean type.

Of course with your technical understanding you have been able to design and implement a fully automated profiling roaster at very low cost. Well done and congratulations on a well thought out design!

Enjoy the kaffe!


#5: Post by jannus »

Very interesting, thank you! It's a nice evolution from a popcorn maker. This looks like it can at least handle some volume, my popcorn maker was stuck on doing about 60g at a time, which makes for a lot of roasting to get a week's worth of coffee.
Even if the same machine is not available elsewhere, the same principle applies.

yokusan (original poster)

#6: Post by yokusan (original poster) »


This tutorial is for this version: ... ram=vitair

It has the same wattage (1400 watt) and therefore I assume it has the same halogen heating lamp. For the maximum temperature: in the tutorial I show how to deactivate the temperature sensor of the air fryer to have full control over the heating. Therefore you can go to higher temperatures with the modded roaster. I was able to reach temperatures of 275°C without beans. However, the plastic material of the air fryer is not made to work at such high temperatures and starts to melt. If you want to experiment with high temperatures you have to add a protective layer of high temperature silicone as I show in the tutorial.


Thanks for the kind words, it is nice to get compliments after having invested a lot of time to generate the roaster and the tutorial. Unfortunately, the automatically generated english subtitles are not good. If it is really necessary I could try to generate an english audio track for the video.


Until last week I always roasted 250g batches, but I wanted to have more coffee this time so I tried 350g. And it worked quite well under 13 minutes. Could be optimized but it tastes very nice for the first try. Here is a pic of the roast:


#7: Post by skipg »

Jan said
Even if the same machine is not available elsewhere, the same principle applies.
I am in the United States, and KLARSTEIN makes the same VitAir as a 1400 Watt unit, 110VAC! It sells for $62.99 on Amazon. There are several models, and here is a link to all of them. Perhaps someone familiar with the various models can comment on which ones would work best. ... _sb_noss_1


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#8: Post by randytsuch »

I remember seeing a recommendation somewhere to not use the one with the controls on top, it was harder to modify.

You want one with the controls in the body ... lig_dp_it

FYI, I bought high temperature silicon sheet from Mcmaster a long time ago when I was making a roaster. You might need some.


#9: Post by Gleekzorp »

Hi Yokusan (and everyone of HB)

My first post on HB; I've joined today, because this project is exactly what I was looking for!

I've kind of outgrown my iRoast and was on the brink of ordering a Gene Cafe or Behmor (not wanting to splash out on a Artisan compatible Hottop) when I discovered this project. I love tinkering with micro-controllers so this is right up my alley.

Just ordered the air fryer, now starting to source the rest of the components. I'm also interested so see if I can replace the Arduino Nano with an ESP32 just because I've got those lying about (although GPIO is on a 3.3V level)

I'll keep you posted on my findings recreating this beautiful project!


yokusan (original poster)

#10: Post by yokusan (original poster) »

Gleekzorp wrote:Hi Yokusan (and everyone of HB)
Just ordered the air fryer, now starting to source the rest of the components. I'm also interested so see if I can replace the Arduino Nano with an ESP32 just because I've got those lying about (although GPIO is on a 3.3V level)

I'll keep you posted on my findings recreating this beautiful project!

Dear Hugo,

I am happy that you want to build your own "BilloJoe" following my tutorial. There is some more information including recent ESP8266 development in the thread in the german forum: ... st-1965450

But I have seen that you already found the thread. I am looking forward to see some pictures of your build.

Regards from Cologne,