Three Questions with Wobble Disk Roaster Maker Larry Cotton

In a roasting world dominated by rotating drums and chambers of propelled hot air, a clever new approach is quietly developing through DIY circles: the wobble disk coffee roaster.

With no drum and no fluid air bed, the home-focused design keeps beans in constant motion on a nutating metal plate at the base of a cylindrical chamber, heated from below. Users can control temperature by situating the heat source closer or farther away, while the disk’s wobble speed is adjustable and chaff exits freely through the open top. The roast starts and ends manually.

The charm is in its simplicity. The chamber can be built from an 8-cup flour sifter, and the wobble disk could be cut from a 13-inch pizza pan. Builders of these devices often pair a low-cost motor with a heat-gun base, then add basic fasteners, wiring and a simple frame. Proponents say a wobble roaster capable of roughly a 350-gram batch can be built for about $100 to $150, all in.

What makes the wobble disk story even more unusual is how it is spreading. Rather than a polished product launch or an influencer push, the roaster’s momentum has grown through old-school enthusiast channels: DIY write-ups, forum threads, videos and shared schematics that move from one tinkerer to the next.

Many of these threads lead back to one man: Larry Cotton.

A retired power-tool designer and part-time community college math instructor in New Bern, North Carolina, Cotton has spent more than 15 years experimenting with home roaster builds. Following early designs involving a spinning basket and then a rotating dog bowl, Cotton said the wobble disk mechanism became the breakthrough that stuck.

“The wobble disk stayed in the picture forever. That was the one thing that I really discovered, and that worked very well to keep the beans equally browned,” Cotton told Daily Coffee News. “It did a really good job of circulating the beans. The beans have to move, and they really do move well with the wobble disk.”

Several of Cotton’s other DIY projects — such as a rotating bird feeder for photography, a MIDI-controlled percussion robot and an electric nutcracker — have been documented by Cotton in Make Magazine, where many of the roaster builds are also chronicled. Cotton has also been regularly featured on the website of home-focused green coffee seller Sweet Maria’s Coffee.

“The coffee roaster is easy. It’s intuitive. There are just a few parts. It’s not that big a deal,” said Cotton. “I’m 99% sure that the wobble disk, at the early phases, was definitely patentable, because no one had ever done it, it works great and everybody can understand it. But it’s been out there too long to be patentable now, and I’m really just happy to be able to share an idea.”

Cotton continues to tweak and test the design, with new refinements expected to show up in future videos. As part of our ongoing Three Questions series, Daily Coffee News reached out to learn more about what makes Larry tick.

Larry Cotton.

Three Questions with Wobble Disk Roaster Maker Larry Cotton

What about coffee excites you most?

My wife’s taste of it. I didn’t drink a drop of coffee until I got married, and she loves coffee for breakfast. When I met her, I didn’t have any interest whatsoever in coffee, never drank any, and she got me drinking coffee. Now it’s almost a ritual.

What about coffee troubles you most?

The tariffs really mess things up. You know, I was buying coffee by the pound for less than $6, and now it’s somewhere between $7 and $8, and way up from there, too. That’s a lot of money for a pound of coffee.

What would you be doing if it weren’t for coffee?

I’m an industrial designer and I’ve built a lot of things over the years. I’m also a musician; I’ve built some crazy musical instruments and stuff that I could never recall how I did it now, because of my age. But I have a good shop, with lots of metal and wood parts. I still dream up things. If it weren’t for coffee, I’d build more unusual clocks — my other main hobby — and cook more, and help clean up the house, and my garage, and, and…

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