It’s not exactly common to come across green coffee beans at the grocery store, but there’s a whole store in Oakland that sells them. As soon as I learned it was possible I had to try.
There are two components, the roaster and the spacer. I ended up making two versions of the roaster itself, but the spacer has worked just fine.
Like pretty much all of my projects, I made this roaster at Techshop. It's also included in my challenge to myself to Make 100 Things.
I purchased steel hardware cloth from Cole’s Hardware and several pipe clamps to hold the cylinder’s shape. A simple threaded steel rod and some pipe caps finished off the roaster. I fitted the metal pieces at Techshop, mostly because I love working there but also because they have nice tin snips that made the work much easier. This could easily be done at home.
After the first roast, we found that 1/4” squares in the hardware cloth were too big for many beans (half of the Ethiopian beans spilled out as we were just about ready to put them on the grill) so we improvised for the day by lining the cylinder with aluminum foil. This worked well but left me looking for a piece with smaller openings to improve the roaster.
The spacer was a less obvious piece but necessary in my situation as the grill we are using is brand new and the steel rod would damage the sides. Depending on your grill, this piece could be optional. I took dimensions of the grill and whipped out a plywood spacer on the CNC mill at Techshop that has a channel for the rod and sits nicely in the bottom of the grill. If you're making your own, I suggest the following:
- Cut out a ring with space inside and outside the rim of your grill's bottom layer
- Provide a groove for the bottom of the grill to sit in. This will stabilize the spacer and keep it in place while roasting.
- Cut a channel across the center diameter of the ring for the steel rod of the roaster to sit in as it turns
- I put in a groove in the top for the lid to sit on as well, and I'd recommend against that. The lid will sit still on its own and if the lid is thin metal on the end like this one, if the lid sits in the groove it'll actually get in the way of the threaded steel rod spinning.
The wood, not surprisingly, browned due to heat exposure within the first two roasts so I wrapped the wood in foil for protection. The next improvements will be finding the hardware cloth with a smaller grid, possibly attaching a slow-speed motor, and protecting the wood. V1 also left me looking for a sturdier solution for the end caps as the fit was excellent with these pieces but the small beans finagle their way out.