Deft. Coffee Roasters.

The past few weeks has been a lesson in the dynamics of falling beans.
I built a couple prototypes for testing how beans will move in the lab sample roaster… This way, I can test, at least visually, how the movement of the beans in the roast chamber will occur. In future iterations of the lab sample roaster, I will be able to exchange barrels out and test different drum configurations and their effect on the development of flavor… But I shouldn’t get ahead of myself… anyway… It’s a beautiful thing.

This is about 0.25 lb of green coffee. As you can see, the vanes are opposing, and in parallel, which will folds the coffee back and forth towards the center of the drum. Three vanes ended up splitting small loads in half which is obviously not a good thing.This is about 1.25 lb of green coffee. To be honest, I liked the way it fell in another test where there were three vanes, but given the problems that were coming up with minimum loads, I think that this is acceptable. The beans stay together well, and though it doesn’t show in this test, the beans integrate/mix within about 45 sec. (That is why there are black beans spread throughout. I painted about 0.25 lb of the beans with black spray paint and laid them in the drum on top of the other beans and timed how fast they integrated. I didn’t think it was necessary to separate them back out…) Anyway, I feel that I have figured out, pretty much as well as I can until I am running real sample roasts what this will look like. It is nice to have the certainty of having seen how the beans will fall. How well they keep together and so on. It’s obviously not a precise science—if it were, roasting wouldn’t be an art—but having gone through this prototyping is giving me both confidence that what I am building will be quality and a much better sense of what is happening inside the drum.This week is my week to draw the mechanicals for this and spec materials… I still need to decide on the construction method. I have a couple options. To slip a stainless steel sleeve inside an aluminum or copper tube, or to press fit machined cooking pots together. I like the latter, but getting pots without the handles, in a reasonable amount of time is my concern. That may actually be a second drum.