Part V · Put it together

The roast simulator

Time to drive. This simulator wraps every idea in the guide — phases, cracks, rate of rise, development, roast level — into one machine you can actually run. Pick a roaster, shape the heat, press start, and watch a virtual batch climb, crack, and finish.

How to drive it

  • Choose a roaster. Air / fluid-bed, a Drum, or the Kaffelogic Nano preset (which locks the batch near 100 g and switches the display to the Nano's own temperature scale).
  • Set batch & airflow. Bigger batches have more thermal mass and climb slower; more airflow means more convective heat (and, on a real machine, more agitation).
  • Shape the power curve. Drag the dots to plan how hard the heat drives over time — this is the one lever that matters most.
  • Start, watch, and Drop. The bean line climbs, the cracks trigger automatically, and the Rate of Rise updates live. Hit Drop when you like the look of it — or let it ride.
★ Flagship

Roast Simulator

A lumped-thermal teaching model — not a physics-grade simulation. The numbers are calibrated to behave right and land the milestones sensibly, so you can build intuition for cause and effect.

Experiments to try

Don't just roast "correctly" — break things on purpose. That's where the intuition comes from.

  1. A clean light roast. Start fairly hot, then ease the power into a smooth decline. Aim to reach first crack around 8–9 minutes and Drop maybe 30–60 seconds after. Check the development ratio.
  2. Cause a crash. Yank the power down sharply in the middle of the roast and watch the Rate of Rise dive — maybe below zero. Read the feedback. That flat, baked result is the fault Chapter 6 warned about.
  3. Drum versus air, same curve. Set a power curve, roast it on Air, then switch to Drum and roast the identical curve. Notice the drum's extra momentum — and the scorching warning if you start too hot.
  4. Go to the Nano. Switch to the Kaffelogic Nano preset and watch every number jump onto the Nano's scale — first crack now reads in the 210s, just like your machine will.
  5. Push it dark. Keep the power up and drop late, past second crack. Watch weight loss climb and the roast level slide toward smoky and bitter.
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Cause and effect, risk-free.

Every lever here maps to something real: the power curve is your heat application, the roaster type is the heat-transfer mix, the cracks and development ratio are the same ones you'll chase on your Nano. Play until the shape of a good roast feels obvious — then go make one for real.

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A word on the model

This is a simplified single-node thermal model: hot air heats the bean by convection (plus conduction on the drum), water boils off and drags the rate of rise during drying, and a small exothermic bump follows first crack. Real beans are messier — but the relationships the simulator shows are real, and they're what you're here to learn.

That's the whole arc: from a grassy green seed to a roast you designed on purpose. Keep the glossary handy, raid the resources when you're ready to go deeper, and — most importantly — go roast something.