HomeRoast Digest


Topic: Additional personal iRoast2 observation (14 msgs / 942 lines)
1) From: Aaron Peterson
Since installing the TC on my iRoast2 it has become apparent that the
temperatures programmed into the iRoast2 have very little correlation
with any actual temperatures achieved.  It does, however seem to have
a lot to do with how quickly the iRoast2 bean chamber heats up.  Here
are some personal observations:
With 3 minutes of 355 setting the beans seldom get over 320F according
to my TC, but I have no reason to believe that the temperature
wouldn't keep rising at this setting, albeit slowly.
If I continue the entire rest of the roast at the 400F setting, I get
to about 450F on my TC generally between 8-9 minutes total roast time,
and have no reason to assume the temperature wouldn't continue to
climb if I didn't stop the roast.
The amount of chaff shed by the beans seems to be the biggest factor
in irregular temperature curves when using consistent weight of beans
and consistent temp/time settings on the roaster.  Less chaff = slower
heat buildup.  For instance, the Sulawesi Toraja shed very little to
no chaff at all, and is really the only batch of beans that was able
to spend much time at all in the third stage of my 3 min - 355, 4 min
- 400, 6 min - 450 program without the temperature almost immediately
shooting up to around 500F (and would be further if I didn't stop it)
according to the TC.
I'm considering removing the chaff collector altogether and coming up
with my own ventilation system that allows for both chaff collection
and continued ventilation of the roast chamber.  That way, the rather
unpredictable matter of how much chaff will be produced by a batch of
greens will hopefully cease to affect the roast much.  And it will
have the added benefit of prolonging the roast time, which I think
will be good for the overall quality of the roast.
Aaron Peterson

2) From: Poutinen, Jay
Interesting observations.  Have you or anyone else experimented with =
profiles that minimizes roast variation.  I roasted Sulawesi Toraja =
tonight and ended up with a lot of variation in the roast.
From: homeroast-admin on behalf of Aaron Peterson
Sent: Thu 3/16/2006 10:18 PM
To: Homeroast Mailing List
Subject: +Additional personal iRoast2 observation
Since installing the TC on my iRoast2 it has become apparent that the
temperatures programmed into the iRoast2 have very little correlation
with any actual temperatures achieved.  It does, however seem to have
a lot to do with how quickly the iRoast2 bean chamber heats up.  Here
are some personal observations:
With 3 minutes of 355 setting the beans seldom get over 320F according
to my TC, but I have no reason to believe that the temperature
wouldn't keep rising at this setting, albeit slowly.
If I continue the entire rest of the roast at the 400F setting, I get
to about 450F on my TC generally between 8-9 minutes total roast time,
and have no reason to assume the temperature wouldn't continue to
climb if I didn't stop the roast.
The amount of chaff shed by the beans seems to be the biggest factor
in irregular temperature curves when using consistent weight of beans
and consistent temp/time settings on the roaster.  Less chaff = slower
heat buildup.  For instance, the Sulawesi Toraja shed very little to
no chaff at all, and is really the only batch of beans that was able
to spend much time at all in the third stage of my 3 min - 355, 4 min
- 400, 6 min - 450 program without the temperature almost immediately
shooting up to around 500F (and would be further if I didn't stop it)
according to the TC.
Aaron Peterson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=

3) From: Bob Adams
I think the problem is that the IR's heat probe is in the base of the unit. 
My roaster, if set at 400F, will increase fan speed if its probe senses temp 
over that setting. With chaff in the collector temps in the bean mass have 
already exceeded this temp before the roaster attempts to rein itself in.
What we need is to splice a bean mass TC into the roaster's heat regulating 
mechanism.
Any EE's out there want to give this a try? I've got an IR1
I would donate in the interest of science

4) From: dballard
Just as an exercise try using 400 for the whole profile. I programed 400 
for 15m and came up with a curve that was very good (just hit cool when 
it feels right). In fact that is what I use now. The final heat is about 
430 in 12 minutes so the last two minutes could use a bump.
David Ballard
Aaron Peterson wrote:
<Snip>

5) From: Aaron Peterson
On 3/17/06, Poutinen, Jay  wrote:
<Snip>
iles that minimizes roast variation.  I roasted Sulawesi Toraja tonight and=
 ended up with a lot of variation in the roast.
I'm not sure what you mean by "variation in the roast".  I have been
referring to the variation between one roast batch and another using
the same weight in beans and the same temp/time program.  I think
changes in program can't have much positive effect on this type of
variation, because it seems mostly caused by the amount of chaff
buildup clogging the screen on the top of the roaster.  My suggestion
is that modifying the chaff collector to allow free air flow
regardless of how much chaff the beans shed is one possible solution.
Bob Adams suggestion is that putting manual controls on the fan to
affect the temperature in the bean chamber is another possible
solution, and I think a viable one.  However it requires that you be
attentive to your roast every time so you can be there to manually
adjust the fan, whereas I would like to get away from that and be able
to get consistent roasts from a preset program.  That is the benefit I
see of modifying/fixing the, in my opinion, deficient chaff collector.
If you are referring to uneven colors / roast degree within one roast
batch, that seems to have the most to do with the characteristics of
beans themselves, and how many you put in the roast chamber.
My Sulawesi roast was more uneven in color than other types of beans
I've roasted.  It seems that the Sulawesi beans expanded much more
than many others I've roasted, and weren't circulated as well through
the roaster as a result.  The darker the beans became, the more even
the roast seemed though.  Good thing I was aiming for a darker roast
:-)
My Ethiopia Harar Horse beans circulated well, unlike the Sulawesi. 
But, there was still a wide variation of bean colors ranging from
white/yellow to city+.  I'm guessing that was caused somehow by widely
varying bean size, density and shape but I'm not absolutely sure
really.  I don't think there is any easy way to solve that type of
problem in any case.
Aaron Peterson

6) From: Bob Adams
Let me clarify my thinking...
The IR's own probe regulates the heat into the chamber using the fan and the 
element(according to Hearthware)although I believe the fan is the dominant 
regulator of heat. The probe tells the fan to increase speed when it senses 
temp above inputted temp. My opinion is that the problem with this set-up is 
that the IR's probe is below the bean mass and not reporting true bean mass 
temp to the heat regulating system.
If one could hack a TC from bean mass into the heat regulating 
system(fan)the very variable issue of chaff blocking air flow(causing bean 
mass temp to rise but perhaps not affecting the IR temp probe) would become 
moot.
The hack would not be manual-the TC would take the place of the IR's own 
probe.
Now, isn't that clearer?
Still willing to sacrifice an IR to anybody who thinks this might work and 
can do it.
Bob

7) From: Aaron Peterson
On 3/17/06, Bob Adams  wrote:
<Snip>
the
<Snip>
t
<Snip>
es
<Snip>
 is
<Snip>
ss
<Snip>
n
<Snip>
me
<Snip>
d
<Snip>
Hah, yeah.  Now I realize that I paraphrased what I remembered you had
written.  Unfortunately I remembered wrong, and now that you explain
it again I remember what you had said in the first place.  Hacking the
TC in the bean bed into the native IR monitoring sounds much better. 
That would solve other issues I have with the iRoast too, and would be
a valuable hack even if we fixed the chaff collector too.  In fact,
the two hacks together might just solve all the problems I think I
have with the IR.  I have my doubts about how well the fan is able to
regulate temperature though fan speed alone once the chaff clogs the
exhaust screen.
Aaron

8) From: Larry English
My iRoast2 died because one heating element failed - it still heated but no=
t
enough to roast, and didn't change when program temp changed.  So heat seem=
s
to be controlled by switching elements on/off.  Of course, fan regulates
heat during a cycle also.
But I've found that I can exert some control over the roast by use of my
rangetop hood fan.  I connect an 18" dryer exhaust hose from "crown" of
iRoast2 to straight up to the hood, with hood filter removed for maximum
airflow.  The hood fan has five settings - most of the time I run that fan
at lowest setting, which keeps the kitchen clear of all smoke, but I can
slow the roast down a little by increasing hood fan speed.  I've started
using that with my FreshRoast as well - though I don't have a tight fit fro=
m
FR to exhaust hose, it still manages to slow the roast somewhat.
By the way, THANK YOU MARIA for immediate replacement of the iRoast2 - I ha=
d
it less than a month when it failed, and Maria got a new unit to me right
away.
Larry
On 3/17/06, Aaron Peterson  wrote:
<Snip>
d
<Snip>
n
<Snip>

9) From: Aaron Peterson
On 3/16/06, Aaron Peterson  wrote:
<Snip>
I experimented with this some tonight (and made a big mess :-).  For
both of my experiments I used 130 grams of Harar Horse, and the
following iRoast2 program:
3 min - 355 F
4 min - 400 F
6 min - 450 F
-----------------------------------------------------------------
Experiment #A:
1) Only attach the one black chaff collector piece that is connected
directly to the roasting chamber.
2)Place an upside down screen collander over the top of the chaff
collector to cut down on some of the chaff flying everywhere.
Results (min - TC temp measurement):
2 - 295 F
3 - 320 F
4 - 345 F
5 - 360 F
7 - 377 F
9 - 400 F
10 - 415 F
11 - 420 F
12 - 425 F
13 - 427 F
14 - 440 F
Comments:
As you can see, this slowed the roast WAY down.  In fact, I didn't
think it was going to reach my target temperature of 440 F by the end
of the program, so I added an extra minute to the timer during the
roast.  After 13 minutes, I still didn't think it was going to reach
my target temp, so I removed the collander (which let chaff fly
absolutely everywhere), dropped the silver middle chaff collector
piece back on top (which changed the airflow and blew more chaff
everywhere) and finally put the black screen chaff collector top back
on so it was completely reassembled at about 13:10.
I was unhappy to have to mess with the assembly and try to help the
roast finish at the last second, so I thought a compromise on the next
run might get things just right.
-----------------------------------------------------------------
Experiment B:
1) Attached the black base of the chaff collector and set the silver
perforated piece inside.  Did not attach the final top/screen for the
chaff collector.
2) Placed a screen collander upside down over the chaff collector to
cut down on how much chaff was flying around my kitchen.
Results (min - TC temp measurement):
1 - 252 F
2 - 304 F
3 - 325 F
4 - 355 F
5 - 372 F
6 - 381 F
7 - 386 F
8 - 404 F
9 - 411 F
10 - 415 F
11 - 428 F
12 - 442 F
Comments:
I was very happy I didn't have to mess with the assembly at all on
this round, which cut down on the chaff mess considerably.  The chaff
on my stove after this roast was barely more than with the chaff
collector completely assembled.  The collander has larger spaces in
the screen than the chaff collector lid though, and covers the entire
chaff collector top with screen instead of the two much smaller
screened openings the chaff collector lid has.
The silver perforated chaff collector piece hovered and vibrated on
the hot air stream leaving the roaster throughout most of the roast. 
It also trapped most of the chaff, but still seemed to allow greater
airflow than when combined with the screen top that comes with the
chaff collector.  Towards the end of the roast there was so much chaff
that had collected around this silver piece that it didn't hover or
move anymore.
-----------------------------------------------------------------
Other observations and conclusion:
I've been noticing that many of my shorter roasts (done with the
iRoast2 assembled "properly") Have looked like city+ or full city, but
are still sour and green when I brew.  I really think longer roast
times would help get the roast through the whole bean.  When I just
use higher temperature settings on the iRoast2, I generally just get
up into vienna and beyond where the beans lose their character.
Just for reference, using the "proper" assembly with a lower
temperature program, this is my curve with the Harar Horse:
Program: 3 min - 355 F, 10 min - 400 F
1 min - 279 F
2 min - 330 F
3 min - 357 F
4 min - 398 F
5 min - 417 F
6 min - 428 F
7 min - 440 F
So, after doing these preliminary tests with minimal effort at
modification, I definitely will be looking for a good way to modify
this thing to get rid of the chaff so that it has no effect whatsoever
on the airflow.  Then I'll also try to add some kind of manual control
for limiting the airflow out the top, since wide open seems like it
might prevent the iRoast2 from reaching a darker roast by the 15
minute max roast time.
Any ideas about what to pick up from the hardware store are certainly
welcome :-)
Aaron Peterson
Versailles, KY

10) From: Bob Adams
Aaron,
Looks like that 2nd roast had a very nice ramp--how'd the roast turn out?
I seem to remember somebody modding the top by removing the screening--this 
would hold the chaff collector down but still increase airflow. I'll give 
that a try this afternoon.
Bob

11) From: Nelson, Frank
Aaron,
	Thanks for doing the experiment and taking good notes.  I agree
that I would consider the second profile near ideal.  I guess the
question now I how does it taste.
	As for the control of the flow, I have been thinking one of
these Iris-Style Flow-Control Valves would be great.  I found them on
McMaster-Carr item # 8153K11 can not get a good link.  They are
expensive here though $367, I don't like that. What I do like about them
from using them in a totally different application is they open and
close fairly linear and very repeatable.  So if you dialed in some
settings you could easily repeat it, also it could be translated to
other peoples set-ups quite easily.   I really like that part.
Frank

12) From: Aaron Peterson
On 3/20/06, Nelson, Frank  wrote:
<Snip>
I haven't tried the roast from experiment B yet, but I will probably
do that this evening.
On the flow control, I was thinking of something similar to the air
flow control levers on outdoor grills.  Basically they are two metal
circles, each with similar air flow holes punched in them.  One is
stationary and the other can be rotated so that airflow is open when
the holes on both pieces match, and closed when they don't.  It also
would allow for degrees of airflow and would, I think, give easilly
repeatable results.  Perhaps it wouldn't cost $360 either :-)
I did some more roasts with different beans last night after I posted
this stuff, and beans without much chaff had a hard time making it
above 430.  So I would cover part of the opening with aluminum foil
until it reached the temperature I wanted.  Generally when I removed
the foil the temperature would hover there instead of going back down
to 430, but I didn't really do enough testing to say that for sure.
Aaron Peterson
Versailles, KY

13) From: Aaron Peterson
<Snip>
Unfortunately, I think all of the long roasts I did last night were
"baked".  I tried the PNG - Kimel and India - Matadakad (which I have
tried before roasted with a normally assembled iRoast2) and they were
both disgusting.
Aaron Peterson
Versailles, KY

14) From: Bob Adams
Hey all,
A little surgery on the lid resulted in one side of top screen being 
excised. Hoping to increase airflow, slow roast down to ensure fully roasted 
bean. Downside--baked beans.
Roast 1 profile:
355F 4:00
400F 5:00
450F 6:00
Note--My temps will be IR onboard temps-not TC
Ramp up was quite good-356F at 7:00, 1st at 7:45. Proceeded to stall from 
there. 360F at 9:00, 388 at 12:00, no 2nd, baked beans. Cool and trash.
Roast 2 profile:
355F 4:00
400F 5:00
485F 6:00
All good to 9:00--1st at 8:00. At 9:00 the IR did something I've not 
seen--Fan kicked down to a fourth speed. Very low-bean agitation  but still 
coming up and over.
10:00 380F
11:00 420F
2nd at 11:15 Cool and save.
Escaping chaff not a problem outside--probably about 10% of total chaff not 
contained and that was the real small stuff.
Am thinking that one could block this one side of no-screen top at anytime 
during the roast to redirect airflow thru screen on other side if a higher 
bean chamber temp is needed.
Bob


HomeRoast Digest