Charcoal Grill Coffee Roaster

FeaturedContest Winner
Picture of Charcoal Grill Coffee Roaster

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.


Remove these adsRemove these ads by Signing Up

Step 1: Version 1 & Lessons Learned

Picture of Version 1 & Lessons Learned
Photo Jul 15, 5 24 09 PM.jpg
Photo Nov 05, 3 26 26 PM.jpg
Photo Nov 05, 3 57 43 PM.jpg
Photo Nov 05, 4 13 16 PM.jpg
Photo Dec 20, 11 58 02 AM.jpg
Photo Dec 19, 4 18 07 PM.jpg

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.

dan30087 months ago

Nice. I've got a nice little fire bowl, so i'm going to have to try this over that :D

Just need to make a roaster :)

acoens (author)  dan30087 months ago

Great! Please share what you come up with here :-)

Figuring out how to make this roaster took some doing. Hopefully, if you follow the steps here, you'll be roasting in no time! I could churn out a new one in an hour or so now if I had all the parts on hand.

vladivastok11 months ago


acoens (author)  vladivastok11 months ago

Hi Vlad, I completely understand. I think this project is doable with traditional woodworking tools. You could get handy with a router and do something fairly similar - the groove for the steel rod is the most important part and that's a straight line.

If you do end up making your own without a CNC, please share what you come up with!

rocklocker11 months ago

This is a great idea. Have you thought about using different types of charcoal like lump, mesquite or even different types of wood chips.As for heat distribution maybe make a rectangular steel box at Tech Shop. Ooh, Ooh and then hook up a small motor. I wish I had a tech shop near me.

I second the use of a motor, perhaps even set it up with an arduino so that you can spin it at different speeds for different time periods, like really fast for 20 seconds then slow for 5 mins. Just a thought

acoens (author)  clockworkfish11 months ago

We do use different types of charcoal. Friends have suggested smoking tobacco leaves in the grill to give the beans a different aroma. All good things to try! I like the idea of the rectangular box to sit under the roaster to control the heat, too.

As for the motor, this would certainly make the process more automatic and might be exactly what some want out of this. We've found it really relaxing to turn the beans with the little crank and we usually do this in a backyard with a group of friends, so there are different 'jobs' that we rotate around between batches and everyone seems to enjoy being hands-on, so I probably won't add a motor to ours. There are some other notes - the roaster is fixed with a lock nut on one end cap, but the other end cap floats to add and remove beans, but while the roaster is spinning different things can happen and with a person actively spinning you get instant feedback if something feels odd instead of accidentally letting a batch burn. That likely points to other things that can be improved if we wanted to invest more time into it.

43totheN11 months ago
Very cool idea. I do hope you're using stainless steel and not galvanized steel: the zinc/zinc oxide fumes from galvanized will get into your freshly roasted coffee and could cause you health problems over time.
acoens (author)  43totheN11 months ago

Good note - I should have mentioned being careful about food safe materials in the instructable. In addition to stainless steel, you should watch that the wooden spacer is solid wood or "E0" grade plywood as some plywood uses formaldehyde based resins or glues, which is also not great to have near coffee beans.

paularellano1211 months ago
that's an awesome project
acoens (author)  paularellano1211 months ago

Thanks! Let me know if you have a go at your own roaster and if you think of any improvements.

the ringer12 months ago
I love coffee and that includes making it myself and roasting it good job man good job
acoens (author)  the ringer11 months ago

Thanks! I love the ritual of drinking coffee and now that ritual includes knowing about where the beans come from and roasting them with friends. Didn't seem useful as part of the instructable, but we make an afternoon of roasting with good friends and food in the backyard. It's been a lot of fun.