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Topic: almost 15 minute roast in iRoast2 (4 msgs / 240 lines)
1) From: Allon Stern
So, yesterday evening I roasted 1 cup (I don't have a scale) of Yemen  
Mokha Sana'ani in the iRoast2. I made it to a full city roast in 14:45
My iRoast2 has the following two enhancements:
	Thermocouple
	Exhaust vent with variable speed fan
I started with a cold machine, which had been off for about a day;  
this is important, because otherwise, the iRoast2's temperature  
measurement will be more accurate and it will attempt to throttle the  
output, pulsing the fan, and maybe even the heat. I want the iRoast2  
to think that its too cold, and have the heat and fan level modulated  
by my setpoints in the program.
I used the following program:
	320 degrees for 3 minutes - iRoast fan on high
	375 degrees for 2 minutes - iRoast fan on high
	395 degrees for 1.5 minutes - iRoast fan cuts to low
	375 degrees for 8.5 minutes - iRoast fan goes back to high
This gives me some warmup, a burst of heat to get over the hump to  
1st crack, then slacking off on the heat to draw out the time spent  
after first crack to EOR. By placing the burst of heat in the 3rd  
stage of the profile, I can shorten it if the roast is going too  
fast. What I can't do is lengthen it; I may change the last stage to  
8 minutes so I have that option, but that would unfortunately limit  
me to 14.30 maximum time (if I don't stretch the high heat portion).  
I'll have to experiment more.
To help with a higher heat warmup on the yemen, I started the roast  
with the exhaust fan turned completely off. Watched the thermocouple  
reading to monitor the temperature as well as the rate of temperature  
change. After about 4 minutes I turned the fan on the lowest setting.  
It's a 12 volt fan, which I am driving with a 24 volt variable  
supply; 6 volts are required to get the fan turning at its slowest  
speed.
I gently increased the speed to nominal (12 volts) as it approached  
stage 3, around 350 degrees or so.
I tweaked the fan speed to keep the rate of temperature increase  
stable, such that I reached the end of stage 3 around 400 degrees or  
so. I think it was actually 406 when it cut over to stage 4 of the  
program.
At that point, I cut the vent fan back to low (6V) as the iRoast's  
internal fan boosted up to high. Then I gradually increased the vent  
speed to slow the rate of temperature increase. I also watched the  
beans closely, and listened to 1st crack as it progressed. It was  
hard to hear (over the iRoar) but around 415 or so it seemed to be  
going pretty good, then settled down at 420. Gradually climbed until  
I hit the cool button at 14:45 total elapsed time, at 446 degrees.
The roast looks pretty, not completely even, but hey, it's yemen. I  
didn't make it to 2nd crack as far as I can tell; the beans' surface  
has a slight sheen, but  is not oily; there are no divots and the  
color looks appropriate. Resting it today, will have it at breakfast  
tomorrow. :)
-
allon
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2) From: sci
Allon,
That's incredible that you got IR2 out to 15 mins. without hitting 2nd. I
have only been able to get the IR2 to go to 10 min without hitting 2nd, but
I haven't rigged up a fan like you.
My typical slow ramp and longer roast is done with the small chaff collector
screen loosened and resting on top of the chaff assembly. Of course, chaff
flies everywhere so I do it outside now. When 1st is rolling, I completely
remove the small screen, letting the unit breathe freely. Even then, the
temp will nudge upward.
Stage 1: 320 5 min (I've found that anything from 320 to 370 yields the
exact same result since temp settings are more like low, med, and high).
Stage 2: 400 1 min (same rationale as your profile, a little extra heat to
get through 1st; here's where the small chaff screen comes off, but the temp
still creeps up slowly. )
Stage 3: 350 5 min (I usually hit cool about 8-10 min range depending on
bean and roast; C+ roasts will end at about 8 min and 425F)
 Is it repeatable? I highly doubt it. It is just how I've learned on my
quirky hot head IR2 to extend roasts. Is any of that any help to an IR2 user
out there? Maybe worth trying since removing the top chaff collector is easy
(use an oven glove).
I love the IR2 for convenience, but it runs too hot IMO and can't be tweaked
easily without unconventional methods. And you can't/shouldn't do back to
back roasts.
Hearthware cust. service really sucks too.
FWIW,
Ivan
++++++++++++++++++++++++++++++++
Date: Thu, 10 Jul 2008 10:47:54 -0400
From: Allon Stern 
Subject: [Homeroast] almost 15 minute roast in iRoast2
To: homeroast
Message-ID: <65EEB121-FD85-4245-B8AD-71B0788585C8>
Content-Type: text/plain; charset-ASCII; delsp=yes; format=flowed
So, yesterday evening I roasted 1 cup (I don't have a scale) of Yemen
Mokha Sana'ani in the iRoast2. I made it to a full city roast in 14:45
My iRoast2 has the following two enhancements:
       Thermocouple
       Exhaust vent with variable speed fan
I started with a cold machine, which had been off for about a day;
this is important, because otherwise, the iRoast2's temperature
measurement will be more accurate and it will attempt to throttle the
output, pulsing the fan, and maybe even the heat. I want the iRoast2
to think that its too cold, and have the heat and fan level modulated
by my setpoints in the program.
I used the following program:
       320 degrees for 3 minutes - iRoast fan on high
       375 degrees for 2 minutes - iRoast fan on high
       395 degrees for 1.5 minutes - iRoast fan cuts to low
       375 degrees for 8.5 minutes - iRoast fan goes back to high
This gives me some warmup, a burst of heat to get over the hump to
1st crack, then slacking off on the heat to draw out the time spent
after first crack to EOR. By placing the burst of heat in the 3rd
stage of the profile, I can shorten it if the roast is going too
fast. What I can't do is lengthen it; I may change the last stage to
8 minutes so I have that option, but that would unfortunately limit
me to 14.30 maximum time (if I don't stretch the high heat portion).
I'll have to experiment more.
To help with a higher heat warmup on the yemen, I started the roast
with the exhaust fan turned completely off. Watched the thermocouple
reading to monitor the temperature as well as the rate of temperature
change. After about 4 minutes I turned the fan on the lowest setting.
It's a 12 volt fan, which I am driving with a 24 volt variable
supply; 6 volts are required to get the fan turning at its slowest
speed.
I gently increased the speed to nominal (12 volts) as it approached
stage 3, around 350 degrees or so.
I tweaked the fan speed to keep the rate of temperature increase
stable, such that I reached the end of stage 3 around 400 degrees or
so. I think it was actually 406 when it cut over to stage 4 of the
program.
At that point, I cut the vent fan back to low (6V) as the iRoast's
internal fan boosted up to high. Then I gradually increased the vent
speed to slow the rate of temperature increase. I also watched the
beans closely, and listened to 1st crack as it progressed. It was
hard to hear (over the iRoar) but around 415 or so it seemed to be
going pretty good, then settled down at 420. Gradually climbed until
I hit the cool button at 14:45 total elapsed time, at 446 degrees.
The roast looks pretty, not completely even, but hey, it's yemen. I
didn't make it to 2nd crack as far as I can tell; the beans' surface
has a slight sheen, but  is not oily; there are no divots and the
color looks appropriate. Resting it today, will have it at breakfast
tomorrow. :)
-
allon
Homeroast mailing list
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3) From: Allon Stern
On Jul 11, 2008, at 1:24 PM, sci wrote:
<Snip>
You are correct that 320-370 gives the same results, while the  
iRoast2 is not modulating. The trick is to keep the iRoast2 thinking  
that it's cooler than its setpoint. For this reason, I put my  
setpoint at the high end instead of the low end to keep the iRoast2  
from otherwise attempting to control the heat; for that reason, I  
could probably have done 5 minutes @ 370 for the 1st stage, but I  
want the heat bump to be the 3rd stage so I can change its duration  
at runtime. The 3 minutes @320 is historical.
<Snip>
If you're moderately handy, you can add a variable speed vent fan. It  
really brings back some control to the operator. The iRoast2 tries to  
be a "set it and forget it" appliance, but in reality, it doesn't  
follow the program accurately and gives very little actual control.
FWIW, I attempted my stretching routine with some Sumatra Classic  
last night, and I believe I barely touched 2nd crack. The  
thermocouple reached 441F, but I had a couple of divots. I stopped at  
14:15.
<Snip>
Glad I haven't had to deal with them.
Oh, and my Yemen roast? Had an AP this morning; might do better with  
another day of rest. It had great body, and a hint of fruit, but I  
was surprised by some really chocolately notes, almost more of a  
Brazillian character than Yemeni. Certainly tamer than my quicker  
roasts have been.
For my second AP, I made some Brazil Daterra Farms Yellow Bourbon to  
compare. Ah, much more body and chocolate, less acid, and more sweet.  
Maybe the Yemen didn't have as much of a Brazillian character as I  
thought, but it was much more muted than the wild Yemen. We'll see  
what another day or two of rest does.
-
allon
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4) From: =?ISO-8859-1?Q?Brayan_P=E9rea?=
Hello to every one, I'm a son of a producer; I have a few weeks roasting.  I
have only roasted SHB beans of my father farm.  I'm using an I-roast2.  The
coffee of my father is from Guatemala, the 5th place in Roasters Guild
Coffee of the Year Competition 2008 ,(8th region Acatenango Valley). The
recipe I have used is:
stage 1      350f             5min
stage 2     375f              2min
stage 3     385f              2min
stage 4                 400f              2min
With this recipe you can experience good body, long after taste, very sweet,
good acidity, caramel syrup taste, peach.  My score to this recipe is 88.5
2008/7/11, Allon Stern :
<Snip>
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