Drum Roaster Ideas, part 1

Here’s something I knocked up based on looking into a range of drum roaster sizes and styles out there – most of these are from homeroasters.org.

Refs for these are:

• RK Drums;
• Open Sky Roaster;
• Brewster’s;
• One from ebay;
• Jim’s 2-pounder;
• itsallaroundyou’s;
• rcwarship’s;

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Of course there are other factors to consider in a drum roaster. These include:

1. Solid or perforated metal on the drum (all of the above are perforated, if I remember correctly);
2. Heat source(s) and amount of heat available;
3. Volume of roasting chamber (relative to volume of drum);
4. Insulation around roasting chamber (and if so, how much?);
5. Airflow (where and how much?);
6. Agitation of beans (what kind of vanes in the drum?);

There are no doubt other factors that I haven’t thought of!

Conclusions (ie. what I’ll need for my hypothetical 2kg roaster):

• Drum volume of around 12 litres – this would be a drum 40cm long and 20cm in diameter;
• Heating equivalent to around 4000W or 14000 BTUs/hr;
• A mainly convective heat source (heat gun – 2000W) AND a mainly radiant heat source (IR or halogen @ ~2000W) – these are highly adjustable heat sources;
• Because of radiant heat source, drum will need to be perforated or (preferably) mesh;
• Smallish roasting chamber (aim for drum volume to be about 80% of total chamber volume) will be hexagonal or octagonal around cylindrical drum;
• Heavily insulated roasting chamber so as to conserve all the heat applied;
• Heat gun also provides an adjustable airflow (some models);
• Airflow will be directed over/through the beans and chamber, with small exit on opposite side to inlet;
• Vanes will be fitted on outside of drum to act as an additional fan;
• Large vanes for maximum agitation – vanes may be used to “scoop” the beans closer to radiant heat source.

A few sketches I worked up:

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