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How-To Guide

What Size Cocoa Bean Roaster Machine Do You Need?

Start from the chocolate, not the drum

The useful question is not how big a drum you can afford. It is how much finished chocolate you need to produce in a week, and how much of your week you are willing to spend roasting to get there.

Work backwards. Cacao loses weight in the roast as moisture leaves, and loses considerably more at winnowing when the husk comes off. So the green weight you charge is meaningfully more than the nibs you end up with, and more again than the finished bars. Plan your capacity against green weight charged, and give yourself headroom.

The sizes

DrumSuitsTypical use
2 LB Learning, single origins, sample roasts Bars for yourself and people you like. Small enough that a batch you get wrong costs almost nothing — which matters more than it sounds while you are calibrating.
4 LB Serious hobby, gifts, market stalls The most common front door. Enough to keep a household in chocolate and hand it out, without a session becoming an afternoon.
6 LB Side hustle, farmers markets, wholesale trials The point where roasting stops being the bottleneck and your refiner becomes one. If you have started taking money for chocolate, start here.
8 LB Small commercial production Consistent weekly output with room to grow into it. Pair with a real cooler — at this size, cooling speed governs your cycle time.
12 LB Micro-factory 10″×24″ drum, rated to 12 lb with a 14 lb maximum, on a commercial 26 RPM motor. Commercial throughput without the commercial machine.

Why turndown matters more than maximum

The number most people shop on is the top of the range. For cacao, the bottom matters just as much.

The 12 LB drum's recommended working volume runs from about half a pound to fifteen pounds. That is an unusually wide range, and it is worth understanding what it buys you. Cacao is more fragile than coffee. A batch charged too thin in a large drum has nothing to cushion against and gets worked by the vanes instead of tumbling gently — which is exactly how people damage cacao in big commercial roasters that cannot be charged below twenty pounds.

Wide turndown means one drum can run a two-pound sample roast of a new origin on Tuesday and a full production batch on Thursday. For a chocolate maker buying beans by origin and roasting each separately, that flexibility is worth more than another few pounds of ceiling.

Buy the controller with the drum

Whatever size you land on, get the RoastPilot controller at the same time. This is not an upsell so much as a warning about sequencing.

Roast cacao for six months without bean temperature and you will build a set of habits around guessing — charge by feel, judge by smell, hope. Those habits are harder to unlearn than they were to acquire, and the roasts you did in that time taught you very little, because they were not measured. Starting with data is easier than switching to it.

Every Everything Kit is available with the controller bundled at all five drum sizes.

Do not skip the cooler

Cacao holds enough heat to keep roasting after it leaves the drum. At two pounds you can get away with a box fan and a colander. By six or eight pounds, slow cooling is both distorting your finish temperature and capping how many batches you can run in a session. The Model R and Model F coolers exist for this, and at commercial volume a cooler stops being an accessory and becomes part of the roaster.

Roasting cacao commercially?

If cacao is your main product rather than something you also roast, email us before you order. We have built drums to customer specification for cacao, including sample-port and probe arrangements, and the right answer for a dedicated cacao operation may not be a stock drum. There is also a custom drum option if you already know what you need.

Common questions

What size RK Drum should I buy for cacao?

Work backwards from finished chocolate per week, remembering that green weight charged is well above the nibs you keep after winnowing. As a rough guide: 2 LB for learning and sample roasts, 4 LB for serious hobby and gifts, 6 LB once you are selling, 8 LB for steady small commercial output, and 12 LB for micro-factory volume.

Can I roast a small batch in a large drum?

Within reason, yes — the 12 LB drum's recommended working volume runs from about half a pound to fifteen pounds. That wide turndown is genuinely useful for cacao, where you often want to sample-roast a new origin and run production batches on the same equipment. Do not charge so thin that the beans have nothing to cushion against, which is how cacao gets damaged in oversized commercial roasters.

Do I need a cooler for roasting cacao?

At two pounds a box fan and a colander will do. From about six pounds up, a proper cooler matters for two reasons: cacao keeps roasting in its own retained heat, so slow cooling moves your actual finish temperature away from the one you aimed at, and cooling time limits how many batches you can run in a session.

Is the RoastPilot controller worth adding at the smallest drum size?

Yes, and arguably it matters most there, because the smallest drum is where you are learning. Roasting without bean temperature builds habits around guessing that are harder to unlearn than to avoid, and it means your early batches teach you very little. The controller is $315 and bundles into the Everything Kits at every size.

Keep reading

We build roasters, not chocolate

Worth saying plainly, because it shapes what you should and should not ask us.

We are a machine shop. We have spent twenty years building drums that apply controlled heat to beans and let you see exactly what that heat is doing — for coffee, cacao, peanuts, nuts and grain. Ask us about drums, grills, burners, motors, thermocouples, profiles, batch sizes, or why your roast is running away from you at minute nine, and you have our full attention.

We are not chocolate makers. Fermentation, origin selection, winnowing technique, refining, conching, tempering, recipes — that is a craft in its own right and not ours.

For that side, Chocolate Alchemy is the best resource on the internet and has been since 2004. John Nanci's complete bean-to-bar guide, his 300-plus Ask the Alchemist archive and the Chocolate Alchemy forum will take you further than we could. We send people there happily and often — and if you want to learn profile drum roasting hands-on, they run an all-day drum roasting seminar that is worth the trip.

Get your chocolate craft from him. Get your roaster from us.

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