Hazardous1966 Senior Member Joined: 26 Dec 2004 Posts: 22 Location: Monterey-San Jose, CA Expertise: Just starting
Grinder: whirly blade Drip: Who you calling a Drip? Roaster: Iroast
Posted Mon Dec 27, 2004, 8:56pm Subject: Building a Drum Roaster
I have several questions on this topic. So, please bear with me. I have been reading through many of the old posts on this site dating back to 2002 for the last hour and my questions still have not been answered. I have read the articles on the "Homeroaster" site on building and rebuilding the BBQ drum roasterand and the questions still linger.
I must first admitted that I am a gadget geek. I see something and instantly figure ways to improve, make bigger or just build my own. Santa brought my girl friend the IRoast and we have already started this great journey of the perfect cup. So onto the confessional; worst part of this is that I as mentioned before I brew my own beer and last night another brewer (gadget geek) and I met at a local pub with our respective counter parts over a fine Winter Warmer Ale. Topic came around to latest "brewing" adventures. Well, I proudly proclaimed the GF and I are now roasting our own coffee.
He inquires about how this is done and the conversation is off with my extremely limited knowledge of roasting, beans, etc. Instantly we are designing a Drum roaster and cooling table using the napkins on the table. Occassionaly the GF interjects asking if her Christmas present is now becoming obsolete. I of course assure her that her gift will be used to create the profile in small "sample" batches, while the bigger roaster will be used for the large "family" batch. Onto the question.
First, I have noticed all of the home drum style roasters seem to have perforated drums. I have noted mention that is to allow the chaff to escape the roasting process. It seems the other GG (gadget Geek) has access to 8" diameter stainless steel pipe and a sheet of perforated SS that can be used to close off one end. In my limited exploration it seems most commercial "sample" roasters seem to have a solid drum. How is the chaff removed from these machines and has anyone made a solid drum home roaster? I have found that most of the roasters have closed doors on the drum. I noted the one on Homeroast with the open end. Does anyone have design plans for an open or conical opening for the drum? We are also considering on a more direct heat approach than the BBQ by placing dual gas elements along the sides of the drum since it is solid wall. Any comments or suggestions on this manner of heating? I have noted comments on drum rotation speeds. Seems they range greatly between 6rpm - 60rpm. We are considering variable speed. Any suggestions on rotation speed v. temp? Or use of one constant speed? Understand Temp Controll is an important factor and have devised a method for a digital probe to ride above the bean surface for the most representatve bean temp. (Very close to keeping a temp on a Mash)
We have two ideas for cooling the beans. One is very close the one depicted on Homeroast. The second is a controlled blast of CO2. My only concern would be the cooling would be too rapid and the cold would break the bean down. Ideas? Comments or suggestions?
I appreciate any input or comments. Thank you in advance.
As for the speed, I don't think it's a matter of speed vs temp. I think it's more of a speed vs mass of bean issue. I've read that small batches of beans are ok with a slower motor but larger batches need a faster drum speed. I've also read something about speed vs drum size. There is a chart about midway through this post
"New Rk Drum Setup" (Search for broken cup's post with the words "Check out the chart")
That same link has some pictures of TheArtfuldodger's bbq drum setup, and his turbo bean cooler. I use a similar bean cooler.
The only professional roaster I've actually seen in use (the Probat) does use a perforated drum. The chaff is collected using a filtering system.
Since you are local to the San Jose area, I suggest you check out the Bay Area Home Coffee Roasters Society over at Barefoot Coffee Roasters: "Bay Area Home Coffee Roasters Society" We really have a blast, and so far have managed not to burn anything down. Not sure when the next meeting will be, but I hope it'll be this month. Chris, the roastmaster, even does a demo roast on the Probat.
Good luck, and keep us posted
Rawman the Expobarbarian.. AKA the Original Jon R.
Bean_Roaster Senior Member Joined: 12 Aug 2004 Posts: 36 Location: Atlanta, Georgia Expertise: Professional
Espresso: Nuova Simonelli, La Pavoni Grinder: Simonelli, Bunn, Delonghi,... Drip: Bunn, Delonghi, etc Roaster: Ambex, Sonofresco
Posted Sat Jan 29, 2005, 10:01am Subject: Re: Building a Drum Roaster
Hey, go for it. Sure, there is risk...keep a fire extinguisher handy. Take lots of photos so you can share your experience.
I'd go for a bigger drum than 8"...you don't want to limit your roasting ability. With a larger drum, you can still drop to a lower batch size, but your upper limit is restricted by the drum size.
Rotation speed will depend on the drum size. But for an 8" drum a 1.5 to 2 sec rotation is probably good. You might consider putting a variable speed control on the drum motor. That way, you can adjust it if your beans are roasting too fast. Don't forget to include agitators to keep the beans hopping inside the drum.
Make sure it is level and the drum is true - you really want to get an even roast. If the roaster or drum are not level, the beans will crowd to one end and not roast properly.
Hazardous1966 Senior Member Joined: 26 Dec 2004 Posts: 22 Location: Monterey-San Jose, CA Expertise: Just starting
Grinder: whirly blade Drip: Who you calling a Drip? Roaster: Iroast
Posted Sat Jan 29, 2005, 1:16pm Subject: Re: Building a Drum Roaster
Rawman and Beanroaster,
thanks for the input about the drum information. The project has yet to begin. I am trying to collect information before the start of the project. There will be plenty of pictures to post and hopefully not shots of an inferno. Heck that does sound like a good name for the roast upon completion. INFERNO Roaster... or does that famous chain coffee peddler hold the rights?
Please keep me posted on the Bare Foot meetings. I actually met Chris and he tookd about 30 minutes to show me the roaster and explain the process. Could be a cool way to get a few more ideas on roasting. So please keep me posted on any meetings in the future.
Bean_Roaster Senior Member Joined: 12 Aug 2004 Posts: 36 Location: Atlanta, Georgia Expertise: Professional
Espresso: Nuova Simonelli, La Pavoni Grinder: Simonelli, Bunn, Delonghi,... Drip: Bunn, Delonghi, etc Roaster: Ambex, Sonofresco
Posted Sat Jan 29, 2005, 2:53pm Subject: Re: Building a Drum Roaster
Hazardous:
Do you have access to a drum roaster you could study? You might benefit from some measurements, etc. I have a drum roaster - 5lb batch - and I could e-mail some pictures, measurements, or whatever might help.
If your prototype works, I'll be glad to front some captial to take the Inferno commercial! Keep us posted.
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