HomeRoast Digest


Topic: I-R 2 tips, questions (3 msgs / 67 lines)
1) From: charles kertay
I got my I-Roast 2  a month or so ago.
I
found that it roasted wa=
y too fast as set up with the chaff collector.
(I guess the chaff restric=
ts the air flow. I would certainly guess this
would make for inherantly u=
nequal roasts when you switch beans)
Since
I wanted a temp probe, I =
got a chimney (metal dryer vent) vented out
the window. With this, the ro=
asts were way too slow! So I programed a
roast profile of 440 degrees for=
 3 min, 460 for 3 min , then the max of
485 for 6 min. With this profile =
it gets me to City roast in about 9 to
10 min., and full FC+ goes off fas=
t after 10 minutes, when the machine
slows down automatically even more, =
(even though  I did not do this
with the programming). I think that going=
 without the chaff collector
like this is definitely the way to go as men=
tioned above. 
The
digital probe is thread through the vent (tiny ho=
le) then down into the
roast chamber. The temp reading varies alot depend=
ing on exactly where
in the chamber I postion the probe. The on-board the=
rmometer does not
register anything like the digital probe.
I need t=
o find a way to keep the probe in one location inside the roast chamber. An=
y ideas?
P.S. When vented outside, it becomes very hard to hear the cr=
acks!=
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2) From: raymanowen
- If you don't want to blow chaff around, you could make a screen wire box
to fit over the end of your dryer vent. If it were something like a big
Teaball clam shell, you could open it to vacuum it out every once in a
while. If it were large enough, you wouldn't have to vacuum it every time
you roasted a few grams.
If there were just one exact position for a thermocouple to read correctly,
every other sensor position would be incorrect.
I assume every position gives incorrect temperature sensing. That saves
looking for perfection. What will drive you to insanity is trying to take
readings with a sensor that moves within the hot zone.
Hot gas flow is highly stratified. The gas molecules move past One Heating
Point, one of the heating coils, and several cooling points- the beans that
are being heated.
For roast-to-roast uniformity, the atmospheric pressure (gas molecule
density), the Number and Size of the beans in the roast chamber, and gas
velocity within the roaster would have to be constant, or compensated for,
among others. Variation kills roasting uniformity.
Want to see a demonstration of non-uniformity?
Fill a canning kettle with water and heat it to boiling. If you stick a
thermocouple probe in it, you'll find it's thermal Disneyland while it's
heating up. Even at the boiling point there'll be temperature variation.
Scene 2 is dry, with high velocity gas passing a red hot wire in an instant,
then releasing its heat to a mass of (much cooler) roasting coffee beans.
Anything that slows the gas flow causes it to spend more time at The Wire,
and pick up more heat to dump in the bean mass.
It's the Infernal Dance of the Coffee Bean.
Cheers -RayO, aka Opa!
"The indisputable truth is that no coffee is fresh if it isn't fresh
roasted." - - Martin Diedrich

3) From: charles kertay
Thanks Ray!
   
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