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However, if you know that your coffee is well graded and should roast consistently, but it is not, or if you are seeing a small number of obviously burnt beans in among otherwise well roasted coffee, your fan speed is most likely too low for the coffee you are roasting. This could indicate a need for re-calibration, but it could equally well indicate an unusual coffee for which you need to make some adaptations.
See Fan speed calibration for how to check if re-calibration is needed.
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The default fan speed for the unit is 14,700 RPM and the input is multiplied by 10. Inputting a value of 25 will raise the fan profile by 250 RPM. A good starting point is inputting a value of 10 (100 RPM) and going from there.
The above instructions will move the entire fan profile up to higher values. If you know that the problems are in specific stages of the roast you can take a more nuanced approach by dragging the blue control points of the fan profile curve to increase specific parts of the curve.
Each coffee is unique and you may need to spend some time dialling this value in to achieve the perfect roast for that particular coffee.
See also
Upgrading to new glass-walled chaff collector
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