ROEST Batch Size Power and RPM Adjustments

When increasing batch size, more energy is required. For example, when moving from a 100 g roast to 150 g, Sorinl recommended increasing power throughout the whole profile rather than only changing one phase. As a practical starting point, he suggested raising the entire profile by about 5–10% power and then evaluating the result. source

Drum RPM and Energy Transfer

Sorinl noted that reduced RPM can reduce energy-transfer efficiency on ROEST because the drum itself is not the main hot mass; the hot air is. In general, he described higher RPM as making the roaster work more efficiently, with more energy going into the beans. source

RPM Guidance by Batch Size

For larger 150–200 g batches, lower RPM may be needed because of space limitations in the drum. For 200 g batches, Sorinl recommended 45 RPM, noting that at this batch size the beans cover the whole drum and efficiency remains high. source

For 150 g batches, Sorinl said higher RPM can be used and that 55 RPM should be fine. source

Experimentation and Possible Bean Sticking

Sorinl said it is fine to experiment with RPM for each coffee. One possible issue is that a bean may get stuck, in which case the paddles can move back and forth to solve it. source