A very basic video about making and testing Popper, the air coffee roaster.
Here’s a video to show a few early versions of the machine, and some aspects I had to deal with in getting this project completed.
I don’t think this is a video of general interest so please don’t expect much, and the quality isn’t great. I was trying to move the camera phone around to show details and didn’t always do a great job. Ugh.
Also I need to make it clear that you shouldn’t do what I do here, because opening up the machine voids the warranty against manufacturer defect. I made the video to provide some background details only, and show how I test temperatures.
Some things I go over here are
A look at an early prototype
Location of the thermal cutout switch that protects Popper from overheating
When I have a unit that turns off before reaching dark roasts, how i move the thermal cutout switch upward to solve the issue.
How I use a thermometer to probe the bean mass
Show a bare version with probe locations for input air and bean temperatures
Deconstruct (partially) a Popper to show how it’s put together
Talk about the unit that easily roasted 140 grams, and why I couldn’t get it built that way 😢
PS – this is in my workshop space where I store the pallets of Popper, hence the motorbikes and cars and such.
It is indeed, a Popper! But Popper is a coffee roaster indeed
We are excited to launch this new home roaster because it offers a great, economical option to start roasting your own coffee. But we also think experienced folks who roast coffee will find it attractive … and perhaps those who like to modify machines too.
Popper is, as the name makes pretty clear, based on the hot air popcorn poppers so many people use to roast coffee. (And in case you are wondering … Popper does indeed do a good job popping popcorn too!) Popper allows user-control of the heat level, fan speed (just high and low really) and the roast time. These can all be fluidly adjusted during the roast cycle.
A Quick 2:00 Popper Roast Run-through
Not high tech… but simple, straightforward, and user-friendly
Popper has no automated roast cycles, beyond a default 7:00 roast and 3:00 cool. You, the user, can “profile” the heat curve and set roast parameters using the front control knobs. But nothing is “preset” for you. If you want a roaster that saves programs, has automated roast curves, or connects to your phone app, Popper is not for you, probably
Turn on the Popper and you see 0:00 on the timer and a green light – the Off position. When you start a roast batch, the maximum time allowed will read 10:00 on the digital count-down timer. But that is not 10:00 of roast time. The final 3:00 on the timer is the cooling cycle. During the roast the light is red, and when the timer reaches 3:00 it turns blue for cooling. So yeah, you gotta do a little math: 5:00 on the timer clock means you have 2:00 more of roasting and then 3:00 of cooling. You can handle it!
The nice thing here is, unlike some other roasters, you can use the time dial to add and subtract roast time during the roast whenever you want. Even if Popper goes into cooling mode, just turn the dial above 3:00 and you can roast more.
In other words, Popper is pretty inuituve for you to control. It’s not high tech but -pretty ok in terms of human tech. And we still think humans controlling and making decisions about the roast process is the best way.
popper*, the coffee roaster was right on the verge of going into production.
… but one thing just wasn’t right. The factory had sent sample after sample, but the fan speed (and therefore the air flow) was not consistent. This impacted the potential batch size.
A late night video chat with the engineers in China made it clear to me though. They were testing under the principle that the roaster should not use the entire pre-programmed roast cycle of 7 minutes. They thought of 0 to 7 as a range so they were presupposing what I wanted was a 4 minute roast!
Well, a 4 minute roast is easy in a popper, but it’s rarely an ideal roast time. In fact, the whole idea of *popper is that the user can fluidly adjust roast time up or down on the fly. It’s a manual, low tech machine, unless you want to get in there with an arduino interface etc.
It’s a machine that rewards people who want to play around with the variables, so it’s simple to do a 7 minute roast just to first crack and add 2 or 3 minutes for development. You just have to be there and tend to your roast, make intuitive decisions and turn a knob. Simple.
(For me I actually feel the 7 minute pre-set roast time can work very well. For City roast I target 5:30 to hear the start of first crack, and the remaining 1:30 for further development. Remember, roast time is relative to the device and the type of thermal transfer. Higher air flow and more movement of the mass means more rapid levels of heat transfer via convection.)
We wanted to create a coffee roaster, one that was a lot like a popcorn popper from the ‘70s.We didn’t want to think up any new design, or new roast method. We wanted to take what works, the air popcorn popper, and roll it back to the way it was 30 years ago.
So we took an old vintage air popper machine we bought at a thrift store in the ‘90s for $4, and sent it to China. We sent it to the factory that still makes air poppers, and asked if they could make one just like that. They said they could.
They sent us back a prototype machine. It looked just like the popper we sent them. Actually it was the popper we sent them, but they added 2 knobs to the front.
From then it was a long (and actually pretty boring) back and forth between Oakland and the factory.
There’s more to tell… but we are trying to drag out the story and make more “content” out of this.