Larry Cotton’s Amazing Home Roaster

May 14, 2015

It’s been a while since someone has sent us photos and video of their hot-rod home roaster.  As the saying goes, good things come to those that wait, so when we got an email from Larry Cotton with this video of his machine, our jaws dropped.


Larry’s machine roasts small amounts (about 3oz) at a time but it allows him to roast continuously without a lot of time lapsing between batches. The open basket gives him a full view of the roasting process which can be difficult with most home roasting machines. Larry says, “I originally wanted to build a continuous, set-and-forget roaster.  Just keep the green-bean hopper full and unload the cool roasted beans at the other end.  All prototypes failed in one way or the other–some quite spectacularly (mostly the “forget” part). So I decided to stay with the small-batch roasting process, but just speed it up. After much trial-and-mostly-error experimentation, I settled on a combination of a small propane campstove and a tilted, open-ended basket.”

The basket moves into 3 positions. Vertical for loading, horizontal for dumping the roasted beans and 45° for roasting. It’s powerd by three Black and Decker electric screwdrivers.
“The amazingly robust little motors are geared down to deliver decent torque at a reasonable speed,” says Larry. A microprocessor automates the the motors so they can turn on and off at the correct time.

“I cool the beans with two small desk fans while the next batch is roasting (I needed something to do!), but this would relatively easy to automate. Lastly, I made a wind shroud to fit around the basket in roasting position.  It speeds up the roasting process in cooler weather.  To make the machine even more portable I also added a swing-out platform to hold the shroud and propane stove.”

And lastly…Larry’s lessons in coffee roasting:

1. It’s fun to build a coffee roaster
2. Be safe; roast coffee outdoors; stay with it always
3. Keep a fire extinguisher handy
4. Nobody likes coffee made from burned beans


Interested in the detailed details? Click here for a step-by-step tutorial showing how it was built.