HomeRoast Digest


Topic: Trying out Jim Schulman's Modified Hottop Profile (19 msgs / 432 lines)
1) From: Tom Gramila
On Wed, 5 Mar 2003, Jim Schulman wrote:
<Snip>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jim,
	I have spent some time trying your profile on my WBI.  I've made
some minor (perhaps) changes, but I think that your approach is a real
improvement to my roasting.  My first try was on some Ugandan -- which I
had never really liked before, so I thought it would be a good choice for
tweaking the roast procedure and making mistakes. I do have a computer
controlled roaster, but the large heat capacity of the WBI makes
implementing a vastly new profile a bit of a chore.
	
	My first try sort of approximated your profile.  After roasting, I
asked my wife to smell the beans and her comment was "Ummmmm, chocolate."
That was a first!  I found that I enjoyed the cup much more than other
Ugandan roasts.  In the past with my modified BB roast profile, if I
stretched out the 230 to 350F part enough to reduce harshness and improve
body, the cup was pretty lifeless in terms of character.
	After a couple of tries I have come closer, as measured, to the
profile you suggest.  A plot of temperatures versus roast time: (heated
air before entering the chamber and measured bean) can be found at:
    http://home.columbus.rr.com/thegramilas/coffee/profile.htmlThe biggest difference with your suggested profile is a
drying/"stabilization" stage that takes the beans to 230F.  I have found
that this is important in getting uniformity in the roast (as detected by
color, especially evident at yellow stages).  If I don't do this, I get
unevenness.  But all that I have seen seems to indicate that adding this
segment this should not change the character of the roast much, since not
much "chemistry"  happens by 230F.  I would be interested to know if you,
or anyone else, think this makes sense.
The Nicaraguan that I roasted using this was pretty delightful.  Intense 
body and aftertaste, but still good balance and definitely not flat.
I had it 18 hours after roasting.
Overall, I think this is a big improvement to my roasts.  Any comments or
further suggestions would be appreciated.  THANKS for the suggestion!
Tom G.
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

2) From: Jim Schulman
Hi Tom,
I guess Rusty Staub does know a thing or two about 
roasting coffee! I believe he's the original 
advocate of "slow start, fast finish" roasts. 
Anyway I'm glad the profile did good for you. It's 
always tough to tell how specific to bean or 
roaster these profiles are.
About the speed to 300F: I can go as fast as I can 
if I'm roasting 100 grams, but have to slow down 
too if I go to 125. Keeping the roast even at all 
stages really improves quality; I guess the beans 
never recover later if they're uneven early. Also, 
your WB1 puts out more heat - I can't go over 550F 
on the inlet.
How do you do the computer control -- via an SSR? 
I'm considering a ramp PID, since manually 
controlling at 30 second intervals is getting old 
fast.
Jim
On 10 Mar 2003 at 0:56, Tom Gramila wrote:
<Snip>
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

3) From: Dan Bollinger
I think this last long, low ramp of 10 per minute, is what makes for a well
balanced cup. Mellowness without destroying the origins. Think simmering a
sauce instead of scorching it. Dan
<Snip>
<Snip>
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

4) From: Tom Gramila
On Mon, 10 Mar 2003, Jim Schulman wrote:
<Snip>
	That's been my impression, and thus my reluctance to "let go" of 
the the 230F stage...
<Snip>
	I run the thing off 140V, so it can make about 2KW of heat.  
There seems to be a pretty large temperature difference between the heater
air and the roast chamber, which continues to puzzle me.  I preheat to
280F heater air temp for a while, but the empty chamber never gets above
180F.  I dont think this is a thermometry error -- I have been able tomake
the two thermometers read the same without airflow. My air reading takes
place in the curved section between the heater and the slots that open to
the roast chamber.
<Snip>
    Yes.  Two thermometers, one output control voltage to switch a SSR.
    I use a calculated percentage of ON time determined twice a 
    second and implemented every 1/6 second.  There some were loop 
    stability  problems measuring once per second, believe it or not ....
<Snip>
	It was frustration with turning a variac knob, and making
mistakes, that drove me to the computer as well.  I had thought about
using a traditional ramp/soak approach, but was worried about it enough to
set up a somewhat different scheme.  I do a sort of ramp soak in my
computer:  I have PID feedback on the heater-air-temp set to meet a time
dependent target temperature. But, and I think this is important, the
determination of when to move onto the next "segment" is determined by one
of: time, heater air temp, or measured bean temp.
	I was very worried that a regular ramp/soak controlling and
measuring the heater -- where the end of a segment would be determined
independent of the bean temp -- would do a poor job of adjusting for
different beans, changes in humidity or ambient temperature, air flow
adjustments, and so on.  And I was worried that the control loop would be
unstable if the input were instead just the bean temperature.  This would
certainly be the case in the WBI with its large non-coffee heat capacity.
	So instead I went for a very flexible control algorithm.  I have
eleven segments in my replica of your profile, 4 of these switch on bean
temperature, two on time alone, and the rest make specific net increases
or decreases in the heater air temperature.  each section has a specific
ramp for the heater air target temperature.
	It may be possible to use a single temperature in - control out
ramp/soak PID on a roaster where there is very little lag between the air
temp and the bean temp, but it just made me too nervous to try.  I was
able to "cobble" together my setup, which allowed lots more control, so I
never had to....
	Tom G.
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

5) From: Jim Schulman
On 10 Mar 2003 at 12:51, Tom Gramila wrote:
<Snip>
That's good. Ramp/soak controllers can really make 
a mess if the actual is far away from the ramped 
setpoint. 
Maybe I should stick with hand control ... I can 
see myself hovering over the PID setup every time 
I try a new bean, worrying about the tuning 
parameters.
Jim
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

6) From: Tom Gramila
On Mon, 10 Mar 2003, Jim Schulman wrote:
<Snip>
	I have to say I rather like my computer setup.  It took me three
tries to get to your profile, and now I can use it again and again.  The
big advantage to me is the repeatability -- especially as one who is still
trying to learn the ropes, and how to tell the difference between beans,
roasting styles, brewing approaches etc.  This allows me to make
controllable changes in roasting and explore the difference.  Small
changes in the roast profile are pretty easy to do.
	The other advantage is that I can try to pay attention to smells,
etc, as opposed to variac settings, which I frequently managed to get 
wrong.... ;-)
	Thanks again for the suggestions!
	Tom G.
	
	PS -- if you, or anyne else, is ever interested in seeing the
code, just send word, -- its not pretty or well documented, but is
reasonably readable....   Someday, hopefully, the interfacing hardware 
will be straightforward!
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

7) From: Ken Mary
<Snip>
Does your heater probe see radiant energy from the hot wire? There will be a
temperature difference due to heat loss and dissimilar environments between
the two measuring points. But I think 100F is too much.
--
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

8) From: Ben Treichel
Exactly the reason for doing this!
Tom Gramila wrote:
<Snip>
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

9) From: Jim Schulman
Hi Tom
On 10 Mar 2003 at 0:56, Tom Gramila wrote:
<Snip>
I took a close look at your heat input (not bean 
temp) and compared it to my voltage settings. My 
adjustements are less drastic than yours. 
I think the larger the bean load, the more 
drastically one has to alter the heat input to 
hold a profile that "goes against" the normal 
exponential curve of temperature change. This may 
mean that the profiling capacity of large 
commercial drum roasters is far more limited than 
the smaller units home roasters use, since they 
don't have the required power to weight ratio.
Wouldn't it be funny if our small roasters, 
properly built and mastered, ended up doing the 
better job?
Jim
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

10) From: Mike McGinness
From: "Jim Schulman" 
<Snip>
Wouldn't surprise me in the least. It's quite often the case with many forms
of cooking (and other things). Mass production oft times decreases
quality...
PNW HomeRoast List Gathering Info' URLhttp://home.attbi.com/~mdmint/coffee/pnwhrg.htmMM;-) aka Kona Konnaisseur miKe mcKoffee
Royally Balance Brewin'
FrankenFormer Rosto Roastin'
Rocky grindin' - Miss Silvia brewin' too!
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

11) From: dewardh
Jim:
<Snip>
properly built and mastered, ended up doing the
better job?
They will almost certainly be more "versatile" (especially the "air" roasters). 
 With almost all "process engineering" as you scale up the plant your range of 
control options goes down as you optimize for a "particularized" process . . .
Deward
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

12) From: Ed Needham
I'm convinced that smaller batch sizes allow more control and better roasts.
How small is only a matter of opinion!
Does a Ferrari drive better than a big rig Kenworth or Peterbuilt?  There are
those out there that would say no, but I probably wouldn't talk to them very
long .
A small 'hot rod' roaster, with adequate and consistent heat, air, agitation
and controls should not have to take a back seat to any roaster.
Ed Needham
To Absurdity and Beyond!http://www.homeroaster.comed
****************************************
**********************************************

13) From: Rick Farris
Does a Yugo drive better than a Ferrari?
-- Rick

14) From: Jim Schulman
On 12 Mar 2003 at 22:11, Rick Farris wrote:
<Snip>
Does a Yugo have the power to weight ratio of a 
Ferrari?
Actually, the barbecue roasters may be the champs 
in that department, but I've forgotten all my 
conversions
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

15) From: Rick Farris
I remember Tom stating recently that his small commercial roaster (I can't
remember if it was his new old Probat or his old new Diedrich) had way more
power to "force" roasts than the small home-style roasters.

16) From: Mike McGinness
From: "Rick Farris" 
<Snip>
more
<Snip>
Uh, I can ramp 80f+ per min from start to Dark Spanish finish if I want,
not that I want! And stall the roast at any point in a matter of seconds. I
don't believe large drums can....
PNW HomeRoast List Gathering Info' URLhttp://home.attbi.com/~mdmint/coffee/pnwhrg.htmMM;-) aka Kona Konnaisseur miKe mcKoffee
Royally Balance Brewin'
FrankenFormer Rosto Roastin'
Rocky grindin' - Miss Silvia brewin' too!
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

17) From: Ed Needham
(to continue with the car analogy) After roasting a number of years with a
Yugo (Melitta Aromaroast), stepping up to a Ford (Hearthware Precision)
improved my roasts immediately.  With that $125 machine, I was able to get
roasts as wonderful or better than those I had been buying from a number of
places.  A whirl with a Chevy (Hearthware Gourmet) was short lived and it now
resides in my basement storage.  A  Toyota Celica GT (one pound BBQ grill
drum roaster) bumped my coffee roasting experience up another notch and
allowed me the luxury of roasting adequately sized batches.  My 1969 428
Cobra Jet Mustang (the larger Frontgate drum BBQ grill roaster) now allows
both quality and larger batch size, as well as adequate control of the roast.
My original point (the part that you snipped from my post) was that  if the
basic heat, air, agitation and controls could be adequate and consistent, a
smaller roaster would produce as good or better roast than a large batch
roaster.
A Yugo does not meet even the minimum qualifications for an adequate car, so
the comparison does not really correlate with a well designed, small roaster.
Ed Needhamhttp://www.homeroaster.comed
****************************************
**********************************************

18) From: Rick Farris
Ed said:
<Snip>
You're probably right.  I was just pondering trying to make a cup of gumbo,
or one biscuit.
-- Rick
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

19) From: Ben Treichel
While your at it you can roast enough green for one cup of coffee :-D
Rick Farris wrote:
<Snip>
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast


HomeRoast Digest