The Artisan Roaster: A Demonstration of the 6kg Bali Design
Introduction
Following numerous inquiries regarding my TEDx talk, I am pleased to present a detailed demonstration of my custom-designed coffee roaster. Developed in Bali over the last four years, this machine has operated without fail, consistently producing two to five batches every single day.
Crafted from solid stainless steel, the roaster is engineered for longevity. My design allows me to offer a unit capable of roasting 6 kilograms for a fraction of the cost of similar-sized commercial roasters. While I have worked with equipment ranging from modified popcorn poppers (50 grams) to a German-made DeLonghi 15kg roaster, this custom model delivers comparable quality to the latter at a significantly lower price point.
Technical Specifications and Design Philosophy
The roaster operates on a hybrid power system:
- Heat Source: Propane, providing tremendous heating value.
- Motor: Electrically powered (approx. 400 watts) to rotate the drum at 70 revolutions per minute (RPM).
- Capacity: Designed to roast 6kg of green coffee. Although the drum is large enough to hold approximately 12kg, it should only be filled to about 40% capacity.
- Expansion Factor: Coffee beans expand by approximately 40% during roasting while losing about 25% of their weight due to moisture evaporation. Therefore, leaving ample room in the drum is essential for the beans to turn freely and heat up consistently.
The Computerized vs. Manual Advantage
Unlike expensive computerized roasters that cost upwards of $65,000, this unit utilizes a simple manual knob to regulate temperature by adjusting propane flow. The speaker argues that computerized controls are largely unnecessary for achieving consistent results, stating that the manual method allows for equal quality without the complexity of buttons that do not fundamentally change the coffee’s outcome.
Operational Mechanics
The roasting process involves two primary burners located at the bottom of the unit. The rotating drum features perforated stainless steel walls. This perforation is a critical design feature: as the coffee roasts, the skins (chaff) fall through the holes into a drawer located underneath the roaster, ensuring the final product is extremely clean with no traces of chaff remaining in the beans.
Inside the drum, specialized fins keep the coffee in mid-air, ensuring even exposure to hot air and the heated stainless steel surfaces. The entire process for 6kg takes approximately 40 minutes, followed by a 10-minute cooling period.
Setup and Safety Considerations
One of the most significant advantages of this roaster is its ventilation requirement. The speaker strongly advises against installing expensive exhaust ductwork. Instead, the roaster should be used in an open area where smoke can escape naturally.
- Location: An open space or a structure with a simple cover (like a lean-to) to protect against rain or snow is ideal.
- Climate: The roaster can perform effectively even in cold climates, provided the smoke can vent properly.
- Safety Note: The unit uses a standard propane tank with a regulator and hose. Safety features may vary slightly by country, but the fundamental operation remains the same.
The Roasting and Cooling Process
- Preparation: Load the drum with 6kg of green coffee (100% Arabica, ideally locally grown to avoid fumigation).
- Ignition: Light the propane burners and allow the unit to preheat with the top open for about 3 minutes.
- Sealing: Close the lid using the locking mechanism. Newer models feature adaptations to ensure consistent airflow when closed, preventing the flame from going out.
- Roasting: Allow the 40-minute roast to proceed.
- Cooling: Turn off the heat and open the top. To accelerate cooling, place a large fan on a chair directly blowing onto the beans. This “rugged” but economical method cools the beans in 10 to 12 minutes.
Results and Quality Control
Upon pouring the roasted coffee, the consistency is visually striking. The speaker aims for a medium-dark roast, which offers the best balance between sour and bitter notes.
- Flawless Finish: The perforated drum ensures no chaff remains with the beans.
- No Tipping: By using a lower, controlled heat process, the roaster prevents “tipping”—the burning off of the bean edges that occurs at higher temperatures.
- Cleanliness: Once emptied, the drum is pristine and ready for the next batch immediately.
Pricing and Availability
For those interested in acquiring this specific 6kg model, the price is approximately $3,500, plus shipping (which may add a few hundred dollars depending on the destination, such as the US). A smaller 3kg model is available for $2,500 plus shipping.
The speaker, Asher, emphasizes that the power of roasting your own coffee is the most important factor in the entire process. This simple, effective, and economical machine represents the ideal solution for small cafes and enthusiasts who wish to control every aspect of their coffee production.
Contact: Asher@FreakCoffee.com
