I just ordered my first bag of green coffee beans and I'm eyeing up my air popper as a potential roasting machine. This is awesome info for me, thanks so much!
Good video. I did a mod article on a popper on "I Need Coffee". Roasted for about 2 years with a Popcorn Pumper. 113 grams per batch. got great results. Just posted on the troutdoc on RU-vid a my bread machine roaster. Just made a template for roasting using Excel. Let you input temp every 30 seconds and give a graph of the roast and ROR in real time as the roast is cooking. Sam Hampton
Thanks, Sam. I have used Excel like that too, and it was a big help. I'll take a look at your bread machine video. Maybe I'll look into that sometime in the future. For now, like you, I've been getting great results with the popcorn popper mod. I've done about 300 roasts in the past months and am recently putting away roasts in Foodsaver vacuum sealed bags in our deep freeze to get me through the winter (too cold to roast outside then here in Chicagoland). I've been doing six consecutive roasts with my chaff collector per day yielding just over a pound. I trialed the storage method last winter and it worked great so I'm storing 15 lbs that way this time. Thanks for your comments !
Excellent build! I'm starting to work on my own, and ran across your posting on Homeroaster.org... You will be saving me a ton of time, giving me a great starting point on my own project. I think your physical build is exactly what I wanted to start with, and your use of thermocouples and a PWM heater controller is where my changes to your design will integrate. Where I'm changing things up is in your profile management. Your profile management is excellent, as a manually controlled system, but my plan is to use computer control to operate the pwm/temperature profile. This should allow me to duplicate what you are doing manually, but with a greater deal of hands-off repeatability. Also, using a computer to read the thermocouples, I should be able to have more than one thermocouple connected at a time, and be able to track other unit temparatures, such as the transformer, and have that as a live display. I'll be using a raspberry Pi, with a color monitor slightly larger than your pwm meter display. Obviously I'll be dealing with the direct values of the pwm heater controller, instead of the volt meter display you used, so that part of the project will require me to take your manual profile tuning and translate that into some sort of logic that I can use to build repeatable and adjustable profiles. The computer hardware I'll be using is simply parts in my pile of "tinker toys", where I've done projects like putting my bbq smoker thermostat on the internet so I can watch my brisket's smoke, and know when I better head back home to tend the 16 hour cook. The smoker control is a completely different kind of project, but it all uses the same sort of parts. I'll skip the internet connection, since roasting coffee doesn't take as long, and instead focus on developing a way to describe the profile to the computer. Probably something simple like *c per unit of time on the ramp up, and a cutoff temperature, as well as graphic based logs.... So instead of taking notes on paper, my system will log the variables, and turn that into a graph. I think the air control is likely difficult to have the computer intelligently control, and it is possible I won't even try to control the air. My first instruction on building a hot air roaster was from a coffee farmer in Hawaii that showed me his home made machine. His roasts 18 pounds at a time, and is completely home made, and runs at one end of his covered deck area where he processes his beans. He doesn't do chafe control, instead he has a stainless steed wire mesh screen (1/8" mesh) made from a recycled fryer basket, and his air flow is enough to toss the 18 pounds of beans up to the top of that basket in a good churning motion... So he goes a bit farther than you do at making sure he gets good bean motion. Obviously his chafe goes into the trade-winds... He roasts for about 6 or 7 other farmers, so his 18 pound batch roaster is well respected by his peers... So I'm thinking of taking some lessons from him, some lessons from you, and see where I end up somewhere in the middle. His farm is on the Kona coast (of course), up the side of the volcano, using coffee trees planted over a hundred years ago, and I'm hoping he will be around for a while to supply me with green beans, but there are so many other regional beans to try as well.... I would have never found your project if we had used different models of popper... So I got lucky with that... I'll have to post the details of my own project, once I have it to the point I can show it.
Good to hear from you. I have a pretty good idea of what you're planning to do in terms of automating the temperature control, and it sounds like fun! I did something similar to profile one of my wife's ceramic kilns for crystalline glaze work about 30 years ago before such control units were readily available, and considered using arduino technology on this project. The approach I used back then was controlling a zero-crossover solid state relay for the 60 amp/ 240 VAC kiln by adjusting a potentiometer mechanically with a 1/2 degree stepper motor. I'm sure there are much more elegant methods available nowadays. :) Having done a couple hundred 91 gm roasts now with the mod in the video, I've settled on roasting and brewing methods that work well for me, however I have noticed quit a bit of variation in heater and fan motor input requirements depending upon ambient conditions -- temperature and wind -- and also upon number of roasts completed in a session -- quite a bit more heater power input needed for the first roast than for the last one. So if you can establish some multiple linear regression equations to use in adjusting both heater and blower power to achieve your desired rate of rise at each point in the profile, you'll indeed be able to improve considerably upon the manual method I use. I'm up to six-roast sets now and the chaff collector is fine for that number with the limiting factor being the case temperature of the blower transformer; hitting 75C in summer ambient conditions after six roasts which is about the limit I want to take it to. The only item that has been a problem is the rocker switches I selected. I've gone through two or three of them so far; luckily I bought 10 for $5.00 and they are easy to change out. Good luck to you: Have fun and always put safety first! (I say this having narrowly escaped catastrophe on more than one occasion ;)
Safety first??!? That's no fun! I have a long and sorted relationship with electricity. One of the toys I liked the most when I was 3 was my uncle's oscilloscope, and tracking down the origin and nature of the 60hz hum present on every metallic or fleshy object... My discovery of electricity itself was a separate event, I touched a power prong that remained in the wall after my mother unplugged a rental rug shampooer... As I felt the 110v surge through my hand, and my feet on the wet carpet, the proverbial light went off and suddenly those squiggly oscilloscope lines, and conductors, and switches and light bulbs all congealed into a rudimentary understanding that there was a great and mysterious power there and it was responsible for everything from the workings of the TV set to the elevators at the doctor's office... by 4 years old I was refining my understanding of the differences between a filament and a fusible link, and at 5 I discovered soldering and resistance welding... At 6 I was making battery-replacement power supplies out of discarded electronics, and developed encapsulation techniques for high voltage connections using epoxy, as electrical tape seemed useless... That was like 1968. By 1987 I was launching an ISP, and in 1989 I was building one of the first smartphone proofs of concept for the Japanese digital cellular network that was starting to launch. But I digress... The coffee roaster project is little more than a PID with a dynamic setpoint that follows the curve of your roasting profile. I had this idea that I would come up with an open-source design that I could publish. But I made a miscalculation... I had scoured the open source ecosystem for PID code back when I was building my Internet connected BBQ controller that I could supervise and operate from my smartphone.. but in general I found some people discussing PID basics, but very little in the was of functional open-source code. Well, it turns out I missed the one that was out there because they didn't use the term PID, so it never came up in an internet search. In fact, it was developed by members of the coffee roaster forum.... I found your design there, but a couple days later I discovered that my whole project is already done... I'm sure you are aware of the guys that developed the arduino controller that interfaces with Artisan... My project has already been done. So I think my contribution will be to document the adaptation of the TC4 to the DC motors present in the Presto and other more modern hot air poppers. The current TC4, developed by people on the coffee roasters forum, is pretty much my whole project already done... Well, that and the Artisan software. The only thing that is missing is to adapt their system to DC motors. Some people have already done it, but from what I hear it isn't working that well because the PWM used to control AC motors does not produce the same type of RPM curve when applied to the power transformer feeding a DC motor. I already know about this problem, and I know that I can fix it, by altering the software of the Artisan fan control to output the fan signal as a control signal to a power supply, and in designing a power supply to power the whole system AND provide a variable output for the fan. Something you should be able to just drop into your current design. I don't know if the control logic will be on the TC4 Ic2 bus, or if I will design an analog output path directly from the arduino... I don't know enough about the TC4 yet. The TC4 has 4 temperature inputs, but if I had participated it would have a single 1-wire bus (instead of Ic2) and the 1-wire bus would be able to run up to 1024 devices such as fan controls and thermocouple controllers. So if I decide I don't like the TC4, what I might do is adapt the arduino code to talk 1-wire instead of TC4. The mind boggles with the possibilities. My BBQ controller design can control any number of BBQ pits, useful in a commercial bbq kitchen... but I don't know if that will be of any use to a professional roaster, I'm guessing not. In BBQ you need more smokers to make more meat... in coffee you just use the same roaster more times in a day... it's not like it takes 16 hours to roast coffee... so roasters are less likely to have a dozen roasters... So doing the work to change to 1-wire would mostly be for me... But eliminating the TC4, and adapting to DC motors might be a double win for the next generation of home roasters...
Wow! Thanks for the detailed account. Sounds like you're having fun, and that's what matters. Lately I've been working with one-setting roasting. I use a Scott Rao type profile that has an initial rapid rise leveling off to a very slow rate of rise just before 1C and then maintaining that out to termination and shut-down / cooling. I've found that there is an initial power setting on the PWM, with full power to the blower, which is capable of producing precisely the curve I am looking for. That means that the entire thing can be controlled with a simple On/Off timer switch for the heating circuit. That setting on the RMS voltage output from the PWM is about 83 and I'm currently fine tuning that to see how it varies with a cold start versus X roasts -- while the popper and associated control apparatus reaches a steady-state equilibrium after about 3 roasts that is dependent upon ambient conditions, the gradual build up of chaff in the passive chaff collector affects air flow rates in a manner similar to that of reducing blower motor speed. So I hope to fine tune the one-setting value according to those parameter values and have a "set it and forget it" roasting process. A different direction than you're going in, but there are many different ways to have fun with this :)
+John Renolds All of that is detailed at HomeRoasters.org in my threads under Forum > All About Roasters > Popcorn Popper Roasters > ChicagoJohn. The history of the development project, passive chaff collector, parts lists, schematics, etc.
I was looking for an easy modification to my Presto Poplite hot air popper to roast green coffee beans. Thanks for showing me your work, Chicago John. I sure hope you left instructions at homeroasters.org about how you made the chaff collector! If not, please do!
Yes, my whole project is detailed there, but you will also find many other threads in which people have done much simpler modifications to their popcorn poppers that work perfectly well, if you want to start out with something simple to see if you like it. You will find details on roaster builds there for just about any imaginable method. Also lots of great information on all the other elements of coffee making. And most importantly, members who will be happy to help you with any questions you might have.
+Rich Kramer I have the prices of components in the parts lists at HomeRoasters.org (see above). As a rough estimate, including the popper, probably under $100.
bi metal overheat switch. This is the most convoluted bullshit I have seen in a while. Plug it in use a 3 inch galvanize elbow for a chimney and shake the popper while you roast takes about 15 minutes.
In retrospect, I can see where you're coming from in that characterization. But I do think that some means of controlling the time temperature curve can be useful and beneficial, depending, of course on what one is looking to do. This whole coffee thing is fundamentally very subjective, and I guess the main thing is just to have fun with it, and that can take a variety of paths. Anyway, thanks for sharing your reaction !
@@JohnClulow Towards the back end of the first crack when it starts to smoke more heavily is generally a light roast. Somewhere at the beginning of the second crack/machine gun is generally medium and about 8 to fourteen slow count seconds into the heavy second crack is a dark roast. That's when they get really oily. That can vary slightly by bean type like monsoon malabar can be tricky because it's crack is weak and you go mostly by the smoking and the smell. I'm surprised you're using a bottom screened popper they all tend to say they are "dangerous" and should not be used but I have used the same one poplite for maybe sixteen years and never had a problem. I do about 5 ounces at a time. I bought mine for 2.98 at the thrift shop. Whenever I see one I snap it up. I should have enough poppers for well maybe three generations. They are one of the few that have the wattage to actually roast a bean. I'm sorry but your video is more of an electronics video than a bean cooking tutorial.
@@abee3515 You're right. That was 6 years ago. I made a better roaster out of a Oreck XL vacuum cleaner I found at a Goodwill. I been usin that there one for the last 5years now. I've roasted about 200 lbs in it so far and while I had to replace the relay, it's been working fine. If you can get a chance to watch that video, I'd appreciate it if you could let me know if you think it's any better. I'm not much of a RU-vid video expert as I'm sure you can tell. :) Thanks for your input! Take care.
@@JohnClulow I still can't believe the comment where the guy said he just bought a bag of beans and watched your video and was still pshyched to roast beans. If that had been one of my first tutorials I believe I would have mailed them back with a note attached- I don't have the requisite skill set. I have to look at your oreck video now. Anyone who can transmogrify a vacuum into a coffee roaster demands it. I shudder to think what you might do with a tube television and a mirror. I thought a rock tumbler and a harbor freight heat gun might work. But alas I'm too lazy.
@@abee3515 I think I saw something on-line recently where someone had fabricated a hopper that fit onto a heat gun. I have a heat gun, a DeWalt, that has a digital display allowing you to set the air temperature. From playing around with air roasting for awhile now, I'd just guess a heat gun blower wouldn't be able to lift much of a bean mass. Probably as well as a popcorn popper, though. A lot of people get started with popcorn poppers. There's a guy I watch on RU-vid -- Aju's Cafe -- that has done a series of videos recently on very simple ways to roast coffee with contact heat transfer instead of air; the Whirly-Pop, for example. There are a lot of ways to get started and then a lot of different avenues that can be explored.
