Popper Deconstruction: Inside an Air Coffee Roaster

deconstructed popper coffee roasters

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 ๐Ÿ˜ข

PS – this is in my workshop space where I store the pallets of Popper, hence the motorbikes and cars and such.

Inside Popper Coffee Roaster

A Home Coffee Roaster Called Popper

Popper Coffee Roaster Front Angle View

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

Popper coffee roaster 2:00 Intro video

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.

Please see the FAQ Page for lots more detail

Here is a slightly more detailed 7:00 Popper coffee roaster intro video…

Popper is a coffee roaster, intro video 7:00

Popper Quick Start Guide and Safety Precautions

Popper comes with some printed guides to get you started and offer safety advice. Here are some image highlights, and the full PDFs are linked below-

Popper PDFs

These come with the machine, but here are printable PDF versions in case you misplace them

Please see the Popper FAQ Page for lots more detail

Popper coffee roaster is here…

Popper Coffee Roaster

It took soooo long but our first shipment of Popper coffee roaster has landed.

After some years of work, we received our first container of roasters. Or poppers. Or both!

The arrival units are roasting to spec : 100 gram batches, 5-7 minutes (or more, or less, it’s up to you).

I made a quick demo video to share with our current sole retailer, Sweet Maria’s:

Some things take time, like manufacturing a coffee roaster …

Popper is a coffee roaster

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.)

Let’s call it February …

popper coffee roaster line art

Popper* will make coffee go pop, but probably pop corn too. And it is coming along nicely. No need to rush to get it made before Christmas, because it needs to do what it’s supposed to do. It’s going to be February I think.

The prototype samples were going well except in one regard: Each seemed to roast a little less than the previous. We ended up with a final sample straining to move 85 grams of fresh green coffee. No!

So we delayed production to balance out fan and heat and the roast chamber vents. I worked on the exit air vents thinking they were constricting flow … but it turned out it was the inlet air vents. And just minor tweaks made big changes in batch capacity.

But those changes impacted the heat curve too and, while I could roast 140 grams, too much heat was blowing by the coffee and out of the roaster. I couldn’t get darker roasts within a single cycle. (I could by adding time, but we need dark roasts to be in closer range).

So now, fingers crossed, last set of prototypes are on the way with new fan speed, and an additional set of roast chambers, 5 in all, to find the best combination.

I think this is it! What I want is a 120 gram target that makes use of the range of air and heat settings, allowing manual profiling with extended roast times, and full roast range.

And with that, I’m able to get some really striking profiles that don’t at all taste like fast popcorn popper air roasts. Low heat warm-up times, ramping up to first crack, and backing off to finish the roast with control. The 10 minute roast profile I did yesterday of Guji Uraga Hare Wato was really the best roast I have had of that coffee. Really fantastic, sweet and floral.

popper coffee roaster line art
popper coffee roaster line art

What’s in a Name? Not Much.

Popper roaster logo
Popper the Roaster Logo Name

So we had some clever names, and over time none of them seemed right. We ended up with a name which is okay, likely not the best. It’s not clever or funny, unless it’s funny in a bad way, like ha ha that’s dumb. But in the case I think it’s okay to be dumb.

I have product fatigue. I am tired of new versions of the same old thing. I am tired of being a consumer and tired of feeling duped. That likely will never end, I am a sucker and I supposed most people are, just at varying intensity levels. (?)

Anyway, you have to give something a name it can be called. You have to “market” it at least to the degree it is being “brought to the market” as a thing to sell, and it needs some name to distinguish it from all other things. We could just point and say “that thing” but it might be confusing.

So there’s this mental exhaustion I have brought on by nearly all shopping except just repetitive grocery type trips. And even those too …for example, walking down the beer aisle at your basic fancy store, and just being tired of all the labels trying to have “personality.” *

I know, ironic since we have a site (ie sweetmarias / coffeeshrub) with a bunch of choices and long reviews and exhaustive descriptors.

So yeah, Popper* and an explanation “popper is a coffee roaster.” I guess for me, 20+ years in home roasting business, there has been some dry (very very dry) humor in pointing at a popper and calling it a roaster. So I started to write popper-roaster, or air-popper-roaster, or air roaster, but appreciated that someone who had no context to understand what it refers to finds any title confusing.

So I guess Popper as a name just ropes in that confusion and claims it.

The other funny thing is the name is too common to be a trademark. Not that we are just saying “yeah, copy us, open source.” I feel like we own this project and put a lot of time and money into it. It’s not cheap for tooling and such in manufacturing.

At the same time, it’s a popper! We didn’t invent that. We weren’t the first people to roast coffee in an air-popper-roaster. We made a lot of small decisions that resulted in this thing, but it’s not that big a deal.

And as it sits it is not the ultimate coffee roaster. It just works well, costs less, is basic and easy to use, and (nudge nudge) it could be made more interesting as well by some clever people in the internet world.

We did our part. Here it is. Well, soon, like probably Oct-Nov 2020.

I can’t believe you read all this! – Thompson

* Things relate as subjects, people relate as objects. This is the basic notion of Commodity Fetishism. It’s the way, for example, cars have “Stance” or “Character” in advertising. And in the world, on the road, express the Taste, Character or Class of the owner. But the person themselves is mute, as an object.

Sumatra And Popper

Sumatra from Aceh area isnโ€™t that low grown generally (1250 to 1800 meters) but can be tough to roast. It often gets a heavy, dark roast treatment that obscures the coffee to a point. Lighter roasting is more challenging.

Air roasters do a pretty good job with this. Itโ€™s hard to scorch coffee in an air roaster … provided you donโ€™t overload it.

Currently we use a 3 barrel Probat for samples but when I have a single sample to check out, Iโ€™m using Popper lately.

Here is a 1450 meter Sumatra from Aceh (near Lake Takengon) roasted for cupping in Popper.

Lighter City roast from the popper for cupping and drinking!

Origin Story #1

We wanted to create a coffee roaster, one that was a lot like a popcorn popper from the โ€˜70s.  We didnโ€™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 โ€˜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.

West Bend Poppery, first version, 1500 watts

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.