Uneven roasting

If you are concerned about uneven roasting, the first thing to consider is the coffee beans themselves. Often, green beans are inherently inconsistent,

with variations in bean size, differences in ripeness at harvest, and different processing methods. It is not advisable to spend time trying to uniformly roast inconsistent coffee beans.

 

■ Cases Requiring Adjustment

On the other hand,

  • If beans are properly graded and should ideally roast uniformly, yet show inconsistency.
  • If most beans roast correctly, but some clearly burnt beans are mixed in.

In such cases, it is highly probable that the fan speed during roasting is too low for those specific beans.

Also, when roasting small batches using BOOST, the automatically adjusted fan speed can still be too high for some coffees.

In this case,

  • Lowering the input roast amount (Load size)
  • Adjusting the fan profile

can sometimes solve the problem.

Adaptations

① Adjust Load Size with BOOST Function

When using BOOST, adjust the input roast amount (Load size) to ensure proper bean circulation. Adjusting during fan preview is best practice.

https://kaffelogicjp.com/pages/fan-preview

② Change the Roast Amount Itself

Reducing the amount of beans being roasted improves bean circulation.
Always check with fan preview for this as well.

③ Change Fan Profile in Kaffelogic Studio (Recommended)

Especially if you plan to share settings with other Kaffelogic users, this method is highly recommended.

How to change fan profile in Kaffelogic Studio

  1. In KL Studio, click the "Fan profile curve" tab. Here you can manually adjust the curve.
  2. In the same tab,
    click "Tools" → "Transform profile".

     

  3. Enter a value in the second RPM input field on the right.
    ○ Positive value: raises the entire fan profile
    ○ Negative value: lowers the entire fan profile

Understanding Fan RPM

  • Default fan RPM: 14,700 RPM
  • Input value is applied as ×10

Example:

  • 25 entered → +250 RPM
  • As a first guideline, it is recommended to try 10 (+100 RPM).

This operation uniformly raises the entire fan profile.

Please check here for details.

https://kaffelogicjp.com/pages/studio_fanprofile

For more precise adjustments

If you know that a problem is occurring at a specific stage of roasting,
you can also make more delicate adjustments, such as dragging the blue control points on the fan profile curve
to increase the RPM only in the necessary parts.

Each coffee bean has its own unique characteristics.
Achieving ideal roasting for a specific bean may require repeated fine-tuning over time.