HomeRoast Digest


Topic: Roast levels: Tom's temps (22 msgs / 592 lines)
1) From: Scott Marquardt
Regarding Tom's indispensable roast level guide:http://www.sweetmarias.com/roasting-VisualGuideV2.htmlDoes ANYONE get these temps? Using the guide when I started roasting a year
ago, I quickly discovered that the temps were all much higher than what I
was seeing with an in-mass measurement in my popper. No big deal, we all
reference our temps to whatever, and get on with great roasts.
But I just started using my first "real" drum (the infrared experiments are
a special case), a very unique unit a machinist friend and I built over the
last three weeks. I'm now probing the bean mass is a superb, reliable way.
And the temps almost identically match what I've been measuring in the
popper over the past year, for the same roast levels and for when particular
beans hit first crack.
In other words, despite not expecting this at all, my drum measurements seem
to have vindicated my popper measurements, and Tom's figures seem quite high
indeed.
What kind of temps are others seeing? If you were to take Tom's numbers and
park your own "real world" numbers alongside them, how much do you need to
add or subtract from one to get the other?
-- 
Scott

2) From: Michael Wascher
I'm seeing similar temps, just slightly lower than Tom's, in my poppers:
375-450 for 1st  ... occasionally an outlier at 350 or even lower
450-475 for 2nd ... occasionally up at 500
On 6/18/06, Scott Marquardt  wrote:
<Snip>
-- 
"There is nothing new under the sun but there are lots of old things we
don't know." --  Ambrose Bierce

3) From: raymanowen
So, exactly what are you after? I could connect your digital TC meter to a
Leeds & Northrup millivolt potentiometer and make the meter read anything
you want to see. You could offset whatever "erroneous" indication you're
seeing to read whatever erroneous number you'd be happy with.
It wouldn't affect the roast unless you believe the fake numbers and roast
to numbers. That is probably the procedure *$ uses to reliably incinerate
the potentially good green coffee they start with.
Temperature readings are ALL FAKE. The only possible hope is that we both
use the same methodology to get our FAKE NUMBERS. It's unlikely anyone has
actually known the bean temperatures during roasting- they reported the
sensor temperature. Unless your installation is identical, it's Apples and
Kumquats.
If you profile the fake numbers achieved during your successful roast and I
duplicated everything about your roasting, maybe I could match the results.
Vielleicht nicht- [Or it could be different-]
Cheers -RayO, aka Opa!
..
On 6/18/06, Michael Wascher  wrote:
<Snip>
-- 
"When the theme hits the bass, I dance the Jig!" - -Virgil Fox at the Mighty
Wichita WurliTzer- 1976

4) From: Steve Hay
On 6/18/06, Scott Marquardt  wrote:
<Snip>
I get pretty close to those numbers with my iRoast2 and a thermocouple at
the bottom of the annular roast chamber.    I suspect your temperature
instrument is out of calibration.  As you mentioned in your email, something
probably not worth the effort of fixing if you are able to get good roasts,
unless you are interested in the science aspect of roasting.
-- 
Steven Hay
hay.steve -AT- gmail.com
Barry Paradox: Consider k to be the greatest element of the set of natural
numbers whose description require maximum of 50 words: "(k+1) is a natural
number which requires more than 50 words to describe it."

5) From: Ken Mary
<Snip>
Tom's info gives the beginning of first crack at 205C (401F), which is
correct more or less. :-)
If you refer to my previous post of April 14 '06 you will see the variation
of first crack temperatures with ramp. These temperatures were determined
with an exposed thermocouple in the bean mass in a non-perforated drum.
I have copied that message below. Sorry temps are C, if you want F, do the
conversion. The ramps are linear except for some endotherm at onset of pops
and begin at about 180C. A likely explanation is that I am measuring bean
surface temperature while the pops are a function of bean internal
temperature.
<Snip>
--

6) From: Scott Marquardt
My OP's first para ack'd your gravamen, and I understand what you're saying.
Part of my concern isn't just the pragmatics of getting good roasts, but
understanding what's going on with the beans. Curiosity and all that. I'd
never be getting good roasts in the first place if I'd left that trait
behind.  ;-)
Steve, I get these measurements with a variety of thermometers, all of which
are fine at 100C.
My temps are taken in the popper in the downflow, with beans generally
between 3 and 5 seconds out of the airflow by the time they're read. My
assumption is that by the time they get there, the air and bean surface
temps aren't very far off.
After a couple more mods, I'll be able to shoot the beans with an IR gun
pretty effectively, so the fun will continue.
On 6/18/06, raymanowen  wrote:
<Snip>
-- 
Scott

7) From: Peter Zulkowski
 From my point of view it is just coincidence that the temperatures of 
the two different roasters match.
I have had no experience with drums, but a lot with a hot air popper, 
and you can put the TC anywhere you want to in that device to see about 
any temp you want to see.
What is mystifying to me is that I have been roasting with my PGR for 
over a year and the first crack has been appearing at higher and higher 
temperatures.
Now it is up to about 420F, from about 390F.
Second crack still happens at about 460F.
First I thought the TC was wearing out ( ha ha) but why would second be 
the same?
Next I figured that the temp is different now because I am not rushing 
to first so quickly, and allowing the beans to be closer to the 
temperature of their environment.
Slowing between first and second is key also.
When you mount the TC in a place that will not vary from roast to roast, 
and you use the same amount of beans, you should be able to create a 
profile that will work for you.
That is more important than what the 'actual' temperature is, imho.
Hmmm.. if the temp of all the beans was the same at the same time 
anyway, would they not crack all at the same time?
Oh my,
should we be shooting for one mighty crack when first occurs instead of 
the bell curve that happens now?
Guess that would mean all the beans would need to be perfectly the same 
too huh ;)
PeterZ
Scott Marquardt wrote:
<Snip>

8) From: Steve Hay
On 6/18/06, Scott Marquardt  wrote:
<Snip>
Scott, that's why I measure them, too, in the iRoast, I believe.  I hit
first crack from 390-400F most always.  How odd.  But, before I made my TC
mod semi-permanent (no drilling or anything) I was getting quite a bit of
variance.  Never quite figured out why..  I've heard rumbling that TC
measurements in a fluid bed can be highly variable, but I am not sure I
understand why.
Very curious; curious indeed.
-- 
Steven Hay
hay.steve -AT- gmail.com
Barry Paradox: Consider k to be the greatest element of the set of natural
numbers whose description require maximum of 50 words: "(k+1) is a natural
number which requires more than 50 words to describe it."

9) From: miKe mcKoffee
While totally irrelevant for my roasting, when Tom first posted his roast
pictorial with the included temps I was somewhat surprised my Rosto bean
mass temps happen to coincide quite closely with Tom's. 
Kona Konnaisseur miKe mcKoffee
Pacific Northwest Gathering IVhttp://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately the quest for Koffee Nirvana is a solitary path. To know I must">http://home.comcast.net/~mdmint/pnwgIV.htmURL to Rosto mods, FrankenFormer, some recipes etc:http://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately the quest for Koffee Nirvana is a solitary path. To know I must
first not know. And in knowing know I know not. Each Personal enlightenment
found exploring the many divergent foot steps of Those who have gone before.
	From: homeroast-admin
[mailto:homeroast-admin] On Behalf Of Scott Marquardt
	Sent: Sunday, June 18, 2006 7:32 AM
	
	Regarding Tom's indispensable roast level guide:
	 
http://www.sweetmarias.com/roasting-VisualGuideV2.html	 
	Does ANYONE get these temps?

10) From: raymanowen
To quote Tom, "the temperatures I give are from a thermocouple probing the
coffee. That is a different measure from a probe measuring the roast chamber
"environment temperature" (probing the air space in the drum), or probing
the internal bean temperature. The later is the most accurate measure, but
is very hard to do."
First, can you tell when a statement is a caveat, or the different
possibilities listed for
On 6/18/06, raymanowen  wrote:
<Snip>
-- 
"When the theme hits the bass, I dance the Jig!" - -Virgil Fox at the
Wichita WurliTzer

11) From: David Schooley
On Jun 18, 2006, at 3:48 PM, Scott Marquardt wrote:
<Snip>
My apologies in advance for the long, and probably boring, post, but  
maybe someone else will find it interesting...
I have 24 roasts on my iRoast 2, and 17 of those have been done with  
a semi-permanently mounted K-type bead thermocouple. The wire snakes  
through the bottom of the roasting chamber between the housing and  
the insulating O-ring. The tip appears to be 3/4" from the wall of  
the roasting chamber and about the same distance from the bottom.  
Doing this has been invaluable as a learning tool, but I do not think  
my results would necessarily be applicable to another iRoast user,  
much less some other roasting method if someone was trying to judge  
the degree of roast by the temperature.
The first variable is the meter. I have Fluke 179 and Extech DMM's  
available. The Extech is a $40 job I got at Frys; it is a DMM, not a  
dedicated thermometer. Given the specifications of the two meters, a  
two or three degree difference in measured temperature would not be  
unexpected at temperatures where beans typically start cracking. I  
got both meters at around the same time and the factory calibration  
should still be good. For accuracy, my money is on the Fluke, so it  
is the one I normally use. A coffee roast puts both meters near the  
upper end of their specified ranges.
The Extech is a much slower meter.  As an experiment, I attempted to  
duplicate the profile Tom used for the iRoast review on the Sweet  
Maria's web site. This is not the same profile he includes in the tip  
sheets, but there is a graph of the programmed, inlet, and bean  
temperatures. Tom ran the thermocouple through the top and down into  
the roast chamber for the review. For my experiment, I ran a second  
wire down through the top as Tom did in his review. I moved the Fluke  
to this second wire and put the Extech on the first one. My interest  
was in how the thermocouple mounting affected the measured  
temperature, so I logged the Fluke reading at 15 second intervals  
while observing the general behavior of the Extech. The Extech  
temperature was always lower than the Fluke during the roast, and it  
was higher during the cool-down, meaning that the Extech was not  
responding as quickly. Five or six degree differences were not  
uncommon during an 8-10 degree per minute ramp. The thermocouple  
mounting made a difference, but the Extech read lower even at times  
where I would have expected it to read higher.
The mounting of the thermocouple also made a difference, with the  
final curve having a slightly different shape than previous roasts  
with the same beans and programmed temperatures. This was especially  
noticeable in the third stage where the measured slope was lower with  
the top-mounted TC. The curves crossed at about 1:30 into the stage,  
and the final temperature was lower for the top-mounted TC at the end  
of the stage and a short time later when I stopped the roast. The  
bottom-mounted TC is in contact with the glass wall of the roaster  
and is separated from the metal bottom by a rubber O-ring. The top- 
mounted TC only contacts the roaster when it passes through the chaff  
filter at the top, and there is a longer run of wire from there down  
to the bead. Conductive heating of the TC wire could explain the  
differences between the two methods. The top-mounted method is more  
accurate, but it is more clumsy when setting up for a roast.
I guess the upshot of all of this is that you cannot rely on someone  
else's temperature measurements to judge the degree of roast. I tried  
it once and ruined a batch of Brazil CoE #13.

12) From: raymanowen
Oops!
On 6/18/06, raymanowen  wrote:
<Snip>
First, can you tell when a statement is a caveat, or the different
possibilities listed for taking measurements can result in drastically
different readings for the same process?
Second, when a measurement "...is very hard to do.", it means that one
person doing the same measurement twice will quite possibly get different
readings. Let alone two different observers with no training and different
equipment and different installations trying to match numbers.
That's insane. The instrumented bean is totally different,
thermodynamically, from every other bean being roasted. The others don't
have holes drilled or pieces of metal inserted, and they tumble freely.
Or, some purist might consider instrumenting, say, 5,500 beans per pound of
roast. You could actually plot the individual temperatures using a
24-channel strip chart recorder and a 225 input thermocouple switch on every
channel.
Kindergarten artwork would look similar, and be almost as meaningful...
The numbers are good only when the same person repeats the same process- the
same roaster, same quantity and same beans. It may be that Tom could step up
to any drum roaster and create a mouth-watering, cuppers' dream roast.
Could a home roaster step up to the same roaster and achieve the same,
following the numbers only? I'm sure there are some that could, indeed. Then
there's the rest of us...
Cheers -RayO, aka Opa!
-- 
"When the theme hits the bass, I dance the Jig!" - -Virgil Fox at the Mighty
Wichita WurliTzer- 1976

13) From: miKe mcKoffee
<Snip>
<Snip>
Exacto mundo. A number of years ago some of us routinely discussed profiles
and sometimes  exchanged roasts of the same bean (before Tom's first roast
pictorial even existed). I remember my Rosto temps were always about 10f
higher for a given stage than the Master Fresh Roast Profiler. (aka Jim
Schulman, also the author of the inFamous Insanely Long Water FAQ) 
Once the differences in temps known and adjusted for, particulary typical
start of 1st and start of 2nd temps, roast ideas and profiles could be
intelligently discussed and duplicated. 
Kona Konnaisseur miKe mcKoffee
Pacific Northwest Gathering IVhttp://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately the quest for Koffee Nirvana is a solitary path. To know I must">http://home.comcast.net/~mdmint/pnwgIV.htmURL to Rosto mods, FrankenFormer, some recipes etc:http://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately the quest for Koffee Nirvana is a solitary path. To know I must
first not know. And in knowing know I know not. Each Personal enlightenment
found exploring the many divergent foot steps of Those who have gone before.

14) From: Scott Marquardt
Well, yeah. But I'd hope no one would imagine that because varying placement
of the TC will vary the readings, that there's therefore no one best place
to park the TC to get as close to bean temp as possible. That's like the old
argument that because everyone's moral perspective varies, there's no
legitimate basis for any morality whatsoever.
This is why I wouldn't agree that it's NECESSARILY coincidence that the
temps would match in different roasters. If I've been extremely careful to
obtain bean temps in a popper, and if I've architected a drum that makes it
a no-brainer to get bean mass temperature, then in some sense I shouldn't be
surprised.
- Scott
On 6/18/06, Peter Zulkowski  wrote:
<Snip>

15) From: Rob Stewart
This is a multi-part message in MIME format.
In the Rosto I moved the probe around a bit, raised it up and down and =
settled in where it read about 410f. when most beans are starting 1st.
Rob

16) From: Scott Marquardt
I wonder if anyone's considered roasting beans in a ceramic drum while
parking the rig inside a CAT scanner or an MRI machine?
;-)
Dang it'd be fun to do weird science with all this.
On 6/18/06, Rob Stewart  wrote:
<Snip>
-- 
Scott

17) From: Jason Molinari
In my drum, the temps depend a LOT on size of batch, as well as profile. If i roast 1/2 lb. my temps are very close to Tom's.
jason
----- Original Message ----
From: Scott Marquardt 
To: homeroast
Sent: Sunday, June 18, 2006 10:31:44 AM
Subject: +Roast levels: Tom's temps
Regarding Tom's indispensable roast level guide:
  
http://www.sweetmarias.com/roasting-VisualGuideV2.html  
 Does ANYONE get these temps? Using the guide when I started roasting a year ago, I quickly discovered that the temps were all much higher than what I was seeing with an in-mass measurement in my popper. No big deal, we all reference our temps to whatever, and get on with great roasts. 
  
 But I just started using my first "real" drum (the infrared experiments are a special case), a very unique unit a machinist friend and I built over the last three weeks. I'm now probing the bean mass is a superb, reliable way. And the temps almost identically match what I've been measuring in the popper over the past year, for the same roast levels and for when particular beans hit first crack. 
  
 In other words, despite not expecting this at all, my drum measurements seem to have vindicated my popper measurements, and Tom's figures seem quite high indeed.
  
 What kind of temps are others seeing? If you were to take Tom's numbers and park your own "real world" numbers alongside them, how much do you need to add or subtract from one to get the other?
 
-- 
Scott
 

18) From: Scott Marquardt
Where/how are you reading your temps?
On 6/19/06, Jason Molinari  wrote:
<Snip>
-- 
Scott

19) From: Jason Molinari
Long TC probe in the bean mass, coming in from the front. Position is quite stable roast to roast.
----- Original Message ----
From: Scott Marquardt 
To: homeroast
Sent: Monday, June 19, 2006 11:06:37 AM
Subject: Re: +Roast levels: Tom's temps
Where/how are you reading your temps?
 On 6/19/06, Jason Molinari  wrote:     In my drum, the temps depend a LOT on size of batch, as well as profile. If i roast 1/2 lb. my temps are very close to Tom's.
 
jason
 ----- Original Message ----
From: Scott Marquardt 
To: homeroast
 Sent: Sunday, June 18, 2006 10:31:44 AM
Subject: +Roast levels: Tom's temps
 Regarding Tom's indispensable roast level guide:
  
http://www.sweetmarias.com/roasting-VisualGuideV2.html   
 Does ANYONE get these temps? Using the guide when I started roasting a year ago, I quickly discovered that the temps were all much higher than what I was seeing with an in-mass measurement in my popper. No big deal, we all reference our temps to whatever, and get on with great roasts.  
  
 But I just started using my first "real" drum (the infrared experiments are a special case), a very unique unit a machinist friend and I built over the last three weeks. I'm now probing the bean mass is a superb, reliable way. And the temps almost identically match what I've been measuring in the popper over the past year, for the same roast levels and for when particular beans hit first crack.  
  
 In other words, despite not expecting this at all, my drum measurements seem to have vindicated my popper measurements, and Tom's figures seem quite high indeed.
  
 What kind of temps are others seeing? If you were to take Tom's numbers and park your own "real world" numbers alongside them, how much do you need to add or subtract from one to get the other?
 
-- 
Scott
 
-- 
Scott

20) From: Scott Marquardt
I've never understood how TCs are placed in drums, on account of the
agitation vanes. Is there a short length of the drum where the vanes are
notched? Is there enough vane "overflow" that a cross-section of the drum
consistently presents a mass that's 100% in the TC's neighborhood?
- S
On 6/19/06, Jason Molinari  wrote:
<Snip>

21) From: Ken Mary
<Snip>
My drums are square cross section and do not need vanes for mixing. I am
guessing here but if common round drums spin fast enough, vanes are not
needed.
My t/c enters the open end at about a 45 degree angle and is positioned
close to but not touching the wall during rotation. It is also aimed into
the deepest part of the bed, about 45 degrees, corresponding to 7:30 o'clock
for a clockwise view of the rotation.
--

22) From: Jason Molinari
No notching on the vanes. The bean mass is "tall" enough in my drum, which is tilted back at about 30 deg., that the beans are flowing over the vanes, and over the TC tip. This is espectially true once it gets to about 1st crack, and the beans have expanded considerably. This works up to about 1/2 lb loads. Below that the beans only fall onto the TC tip..so the temps are a bit different.
jason
----- Original Message ----
From: Scott Marquardt 
To: homeroast
Sent: Monday, June 19, 2006 2:49:43 PM
Subject: Re: +Roast levels: Tom's temps
I've never understood how TCs are placed in drums, on account of the agitation vanes. Is there a short length of the drum where the vanes are notched? Is there enough vane "overflow" that a cross-section of the drum consistently presents a mass that's 100% in the TC's neighborhood? 
  
 - S
 On 6/19/06, Jason Molinari  wrote:     Long TC probe in the bean mass, coming in from the front. Position is quite stable roast to roast.
 ----- Original Message ----
From: Scott Marquardt 
To: homeroast
 Sent: Monday, June 19, 2006 11:06:37 AM
Subject: Re: +Roast levels: Tom's temps
Where/how are you reading your temps?
 On 6/19/06, Jason Molinari < jasonmolinari> wrote:      In my drum, the temps depend a LOT on size of batch, as well as profile. If i roast 1/2 lb. my temps are very close to Tom's.
 
jason
 ----- Original Message ----
From: Scott Marquardt 
To: homeroast
 Sent: Sunday, June 18, 2006 10:31:44 AM
Subject: +Roast levels: Tom's temps
 Regarding Tom's indispensable roast level guide:
  
http://www.sweetmarias.com/roasting-VisualGuideV2.html   
 Does ANYONE get these temps? Using the guide when I started roasting a year ago, I quickly discovered that the temps were all much higher than what I was seeing with an in-mass measurement in my popper. No big deal, we all reference our temps to whatever, and get on with great roasts.  
  
 But I just started using my first "real" drum (the infrared experiments are a special case), a very unique unit a machinist friend and I built over the last three weeks. I'm now probing the bean mass is a superb, reliable way. And the temps almost identically match what I've been measuring in the popper over the past year, for the same roast levels and for when particular beans hit first crack.  
  
 In other words, despite not expecting this at all, my drum measurements seem to have vindicated my popper measurements, and Tom's figures seem quite high indeed.
  
 What kind of temps are others seeing? If you were to take Tom's numbers and park your own "real world" numbers alongside them, how much do you need to add or subtract from one to get the other?
 


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