I am working my way though the drum dimensions… I figured that it would be easier to build a prototype of the drum than try to envision how the beans are going to fall over the vanes, how many there are, etc… so I built this. My friend Brian (who is helping me build this) squeaked out a little jig that I could put two tire hubs on it—it’s suuper crude, but it works well enough that I can see what is happening inside the drum. The image is just the PVC tubing that I got to simulate the roaster drum before I put in vanes and sealed the back end….
What did I learn? That the depth of the drum is going to be a different ratio to the diameter than I had originally thought—slightly shorter. I need to do more testing around the vanes… I realized (duh) that they need to have a ratio to the depth of the coffee. If the coffee is going to fold correctly, keeping a bean mass, but constantly rotating the position of the coffee beans from being in (brief) contact with the drum wall to positioning it away from the drum wall, I didn’t get it right this time around, but that’s what prototypes are for…
Anyway, more pics after the more >
this is the side view, showing how the drum sits on it’s jig…Like I said, nothing fancy
The vanes are too angled, and not so sure that setting them opposite from each other is the right setup. After spinning a little over 1.25lb of green beans in this set-up, I realized that the way these vanes are set up just aren’t working… Next test will have straighter vanes with a lip on the front end to turn beans back, and also three vanes to keep the beans folding more evenly. I believe that these are too short as well.
You can’t really tell here, but the beans are well over the vanes.. It seems to make them fall from about 70° to 180° moving from the lowest point. Not the best if you want the beans to be constantly moving..
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