It all started with discussions with friends and my siblings. Usually answering the question: "what the heck got you into roasting your own coffee???"
When I explain and demo why (pick up about 19 oz of green coffee for about $8 - and it's better than $18/lb or even $10/lb coffee), the next statement is, "well that seems like a fairly big investment - yes, I see that in 30lb of coffee you've paid off your $300 roaster... but I'm not willing to spend three bills. I might do it if I could manage with stuff I have around."
In essence, even though the Behmor is an excellent device, the multihundred buck price tag was a bit much for people to consider seriously that weren't true coffeegeek under the skin.
However, I just roasted 300g of India Giri-Region Chandrakan Estates 2010 crop, with a total of equipment less than $60.
First, having none, I borrowed a heat gun and used a stainless mixing bowl to roast 75 grams of beans with a whisk. Worked very well.
I picked up a heat gun from Harbor Freight for $32, and a bread machine from the Salvation Army Thrift Store (Welbuilt ABM8200, 2lb) for $8.
I used an old collander - screen type - the kind you can pick up for about $0.50 at a yard sale, and an old bucket to make a bean cooler (previously built cooling contraption).
Open the bread machine (2 screws) and take the thermister off the side of the baking chamber, and unplug the heating element (so it doesn't draw current) and insulate the terminals and secure. Then, figure out where the knead cycle happens (on dough setting, usually 10 minutes into the cycle after mix and rest).
When it starts the knead cycle (approximately 20 minutes long), dump the beans in, point the heat gun in and go. I was timid at the beginning, but managed to coax a rather long 1C out of the batch - but it still turned out great. After 1C and beginning 2C, dump the beans into a cooler and call it a roast.
Knowing what I know now, I'll probably hit it with full power rather than sneak up on it - I'll use my last thermocouple to get a bean mass measurement, and I'll probably sandblast the teflon out of the breadpan, but the resulting roast was remarkable.
Unexpected: -The amount of chaff flying about your head just prior to and at 1C. Don't let it clog the gun!!! -Ease. I would have home roasted earlier if I had known it was this easy.
I look forward to comparing same beans same roast level between my Behmor 1600 and my cheap BMHG method. Best of all, cost of entry is no longer an excuse... :^D
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
Posted Sat Sep 24, 2011, 2:52pm Subject: Some pics and status of my new BMHG setup
I've been puttering around with the old breadmaker setup. Spent some time with a bit of sheet metal and some 3" duct.
Note the $3 radio shack switch in the lower right - plug in and click on, the motor cranks the kneading agitator. I tossed the rest of the electronics out, just wired in the switch and connected the start capacitor and I was in b'ness.
(Click for larger image)
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
A closeup of the sheetmetal top (and cooling position for the Heat Gun)
(Click for larger image)
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
So, I've found out that it does 300g REALLY well - too well, as a matter of fact. The HG has 6 heat settings for two fan settings. I clicked it on high and started 300g of India Giri-Region. This is typically 10ish minutes to 1C at around 415°F on the Behmor.
...and only about 5 minutes without intervention on this setup. The batch was already at 300°F at 3min 30sec, and rising at about 25°F per 15 seconds. Typically, I'm looking for about 12°/15sec for the start, coming down to about 8-9°F/15seconds by about 6 minutes in.
Since I was targeting about 1C around 10min and finish roast at 13-14 min (15ish sec into 2C), I had a hard time - the grassy smell came on early, then baking bread, and was hitting 1C (even with several temp drops on the Heat Gun) right around 7 minutes.
It's kinda comical - chaff drifting out of the "chimney" reminded me of the bubbles coming out of that vehicle on Willie Wonka & the Chocolate Factory, the bread machine rattling away...
In the end, I think it was a bit quick but still looks and smells great. I'll find a happy medium next batch.
So.... I figured I'd try 600g, since it was so good at 300g.
You guessed it, bad idea.
It started out ok, but by minute 5, it started producing chaff - a buttload of it. I had to suck it with quick bursts from the shopvac. It was way behind temperature by minute 5, then the bean temp started to stall out around 320°F by 7 min into the roast. It seemed to not go right after that - stalled temp creeping up about 5°F/minute, chaff blurping out the chimney. I wondered how this was going to end.
I figured I should have been around 415°F-425°F at minute 9-10, but nope, it sat around 335-340°F. I figured I'd never see 1C, until I heard the distinct sound of first crack at 10:30 into the roast. Bean temp at 350°F, but definitely, there it was, the popcorn sound of first crack.
Really?
This continued, then gained momentum over the next 3 minutes, at 13:00 into, it was starting to smoke, but first crack was still well underway. Confused (as always, huh?), I tried dropping the input temp to see if I could manage the smoke. Then, the temp (which was gradually climbing during 1C) started to stall, so I boosted the input temp back up.
I wondered now if 1C would ever end!
It just never really showed signs of slowing down, crackle-pop-crackle. Then, I heard the snapping of 2C - WHILE 1C was still going. Yikes!
I let it go about 30-45 seconds into what sounded like both 1C and 2C - and finally pulled it and dumped a HUGE amount of beans into my collander cooler. Well, didn't think THAT through either. My collander wasn't prepared to handle 500g of hot, crackling and popping beans - it was just a teeny bit undersized.
Then, I realized what happened.
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
Apparently, 600g of beans is too much for my new device to handle. I wouldn't DREAM of trying that many in the Behmor, it has a hard enough time at 300-350g.
The net result was a mottled mess of roasted coffee. The bulk of it was pretty nice - about FC. With sprinkled cinnamon bits (amounted to approximately 30g of that in 500g of roasted coffee) throughout. And peppered along with it were glimmering near-black and smokey bits (about 24g of THAT).
I know that's what it consisted of because I ended up dumping the batch on my kitchen table and creating a "Starbucks" pile, an underroasted pile, and the bulk pile.
<shrug>
Oh well, we live, we learn. No fire, no sparks. I learned something in the post analysis:
I think the depth of the green coffee was too much for the agitator in the bread maker - not enough circulation of the beans. Kinda like when you overfill a top-loader washing machine. The heat gun just sat and cooked the top layer longer than the middle and bottom. The thermocouple was stuck all the way into the bottom of the bean mass. I believe this layer is basically the underroasted bean layer. The rest was striated throughout the roast.
As the temperature rose in the batch, the top reached well above 400 while the bottom was lagging behind by 50-80°F. When I thought 1C and 2C were happening at the same time, they actually were. Beans burning at the top while the bottom were struggling to reach 1C.
I went back and looked at what 600g, 550g, and 400g looks like in the breadmaker with the kneading bar working. I THINK that 525g will work fine - looks like lots of circulation of the batch, but much above 550g doesn't get agitated enough.
525g is a good number - on average it should yield around 450g, or approximately a pound of roasted coffee.
Onward to more roasting adventures!
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
I recently decided to try a new roasting method too I built a SC/TO for about $75. I've been experimenting with it for a few days now and I'm very satisfied with the results. The SC/TO gives me a lot more control than my Behmor. I'll keep an eye out for an old bread machine next time I'm at a yard sale or thirty shop so I can give this method a try.
No doubt a heat gun/bread machine has all the right stuff for roasting coffee. Your design has the top enclosed to reduce environment temperature gradient. I would add a window and light so you can monitor the beans during the roast. Now add an environment temp probe just below the heat gun and just above the bean mass. This is the roast temp you throttle control to achieve your desired profile. Completely pre-heat the vessel before adding the beans.
Actually, I was going to add a small 1/2 periscope mirror in the "chaff chimney" and use a flashlight to look in every once in a while.
I've got the current thermocouple probe down the side to the bottom of the bean mass - figured that if the BM was mixing properly, this was as close to bean mass as I'd ever get. I agree that I might do well with an environment temp probe in addition, but figured that bean mass temp was probably more important.
On the 300g batch, I was delighted at the responsiveness of the temperature to changes in the heat gun setting. One thing about roasting with the Behmor is that it takes the thinking that you are in control of the roast away from you - you're along for the ride and all you really get to control is letting some heat escape (door cracking) and deciding when to stop the roast.
I suspect that I will probably have a good idea at what the bean temp profile should look like and be able to dial the heat up or down to anticipate the end result.
I preheated the bread pan for each batch to 350°F by getting the thermocouple up to that temperature, then dialing back the heat gun until the temp stabilized to about 350°F on the lowest temp setting. Took approximately 3 minutes to complete this process. It was definitely hot, no doubt about that. Then, dump in the beans and record the drop of the temperature as the beans soak up the latent heat in the pan.
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
Given only one temp probe, yeah, I would likely put it in the bean mass every time. A reasonable proxy for environment temp may be obtained as you have for the preheat; Without a bean load, the BT becomes the ET probe. You know where to set for a steady 350F in the chamber, so then find what setting will give you the required finish ET (maybe in 450-475F range). Drying phase likely will work around 350F, then ramp to the finish temp setting for 3-4 minutes and you should be close; hold that setting until completion. My poppery is not quite so predictable in this regard, and may be mostly due to variance in air flow restriction of the bean mass. The heat gun should be more consistent in this regard, allowing for ambient temperature changes.
Strictly speaking, the bean mass should not be allowed to loose heat to any part of it's environment through the entire roast; not until it is dumped for cooling. Any measure you take to improve your roaster in this regard is effort well spent.
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