HomeRoast Digest

Topic: [Roasting_Data] Re: Howdy (8 msgs / 218 lines)
1) From: gin
 needs it's own coffee academy. Wouldn't that be nice...<<<
yes, and a whole hell  of a lot more...
yes, I will step off of my soapbox.

2) From: Bruce Carlisle
Ben, Thanks for the response!!! Gary was right when he said this 
group would be a good resource.
I'm curious mostly about your "user interface" and what parameters 
you consider necessary to control the roast.
I can see three TCs. Not sure about 4 unless you want 2 in the roast 
chamber. (Maybe a TC on the triac to prevent damage?)
What kind of safety precautions do you intend to include in your 
design? I'm thinking about sensing the airflow so that the heater 
isn't run without airflow. Anything else I should be considering?
------------------------ Yahoo! Groups Sponsor --------------------~--> 
Make a clean sweep of pop-up ads. Yahoo! Companion Toolbar.
Now with Pop-Up Blocker. Get it for free!http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/JJTolB/TM--------------------------------------------------------------------~-> 
Yahoo! Groups Links
<*> To visit your group on the web, go to:
   http://groups.yahoo.com/group/Roasting_Data/<*> To unsubscribe from this group, send an email to:
<*> Your use of Yahoo! Groups is subject to:

3) From: Deward Hastings
The four useful measures (apart from "time", of course) when "managing" =
air roaster are:
   Inlet (to the roast chamber) air temperature,
   Exhaust air temperature,
   Bean temperature,
   Air flow.
A fourth temperature measurement, which might be of some modest help in
heater control, is ambient temperature . . . but ambient has no effect =
the roast itself.  As a practical matter (assuming adequate airflow and
available heat) inlet air temperature and bean temperature are =
sufficient to
"define" the roast (determine and control the roast profile), and only =
air temperature needs to be controlled.
Difficulties arise measuring bean temperature because the beans are =
in a (typically much) hotter fluid which makes direct (contact) =
imprecise.  Insofar as possible the measurement must be taken outside =
primary heating (airflow) area of the roast chamber, while still =
sampling the bulk of the bean mass.  IR measurement is complicated by =
thermal vulnerability of the sensor, and compromised by the differential
between surface and interior bean temperature, especially during periods =
rapid heating.  IR thus reads "high" during heating, though not as much =
does a contact probe in the air stream.
I have not found an inexpensive and reliable sensor for measuring =
airflow in
a 500 degree (exhaust) air stream.  The inexpensive flow meters I have =
are plastic, and would fail at that temperature.  Measuring airflow at =
inlet requires the additional complexity of an inlet plenum/flow guide . =
. .
(the exhaust will typically already be contained to allow chaff =
The value of a flow interlock (except for power control . . . i.e. never
turn on the heater without at least power to the fan) is probably small =
. .
. the inlet air temperature probe is probably enough to protect the =
in all but the most extreme circumstance, and replacement heaters are
inexpensive compared to the protection device itself (although perhaps a
simple vane on a microswitch could be rigged as a go/no-go for the =
At one time I was actively experimenting with all of the above =
digital thermometer, "homebrew" TC probes, IR windows, flow diverters =
but at some point I realized that I was managing to roast acceptable =
whether the "gadgets" worked or not.  It has been a while since the toys
came out of the box and I've used anything more complicated than a Rosto =
a variac (or CVT), supplemented by eyes, ears and nose and a simple =
Maybe next year, when all the other "projects" are done . . . .  =
available for "advice", though . . . .

4) From: Gary Townsend
You know, this place has the best classroom available anywhere, and
it's free. I learned more here in 4 months, than I ever did in school.
Really. I do more coffee related research on the web, than I ever
thought about doing on any other subject, ever. Methinks this country
needs it's own coffee academy. Wouldn't that be nice...
 Deward Hastings  wrote:

5) From: Pecan Jim Gundlach
I've taught at a university for over thirty years and I wish the 
university could be as effective at teaching as this list and the 
internet resources that it links to is.
        Jim Gundlach
On Dec 2, 2004, at 10:35 AM, Gary Townsend wrote:

6) From: Les
I think it has something to do with motivation!
On Thu, 2 Dec 2004 12:39:32 -0600, Pecan Jim Gundlach

7) From: AlChemist John
It is indeed a great resource.  On that note, I am looking for stocking 
stuffers for some *$ drinkers and need some help.  OK, not really, but I am 
looking for a place to get some coal.  Does anyone actually use it? or have 
some around locally?
And I too have learned more on this list about practical applications of 
technology that any class ever gave me.
Sometime around 10:39 12/2/2004, Pecan Jim Gundlach typed:
John Nanci 
AlChemist at large
Zen Roasting , Blending & Espresso pulling by Gestalthttp://www.dreamsandbones.net/blog/http://www.chocolatealchemy.com/

8) From: Ben Treichel
Bruce Carlisle wrote:
ambient inlet temp, roast chamber inlet/bottom, middle of bean mass, air 
above bean mass.
I have an interlock that prevents heater voltage w/o fan voltage 
present, but no air flow sensing.
Ben Treichel
Program Manager
S.E Michigan
248-232-7365 (o)
248-935-6845 (m)

HomeRoast Digest