Below are some movies that I made when I wanted to learn more about the "fluid bed" created by the three poppers that I had at the moment: a brand-new Toastmaster, a Poppery II (found at a thrift store), and a Wearever Pumper (supplied by Les "Dr. Crema" Albjerg).
Because I was doing a lot of experimenting that was going to result in unusable coffee, I used black-eyed peas instead. They are a bit denser than green coffee -- so, the movement is not the same as if it had been actual coffee. Nonetheless, the movies are instructive as they show both the convection pattern and relative fan strength.
The thing to notice about the Wearever Pumper (which is different from the Silex Pumper -- which I will film eventually) is that it has the strongest fan and most uniform pattern. The Poppery II and Toastmaster have similar convection patterns but the Toastmaster's fan is much stronger (at least in my units). The strength of the Toastmaster's fan combined with the pattern is one of the reasons that actual roasting coffee sometimes jump more than it swirls as it becomes less dense. For this reason, tilting the Toastmaster helps an awful lot as it restores the 'swirl'.
| Wearever Pumper | Toastmaster | Poppery II |