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Topic: Ruminations on the QM3 and testing results (5 msgs / 109 lines)
1) From: Frank Parth
After having the Quest M3 now for several weeks I have to admit this is the most fun I've ever had
roasting. I find myself wanting to drink more coffee just so that I can roast more. The amount of
control and consistency it offers is a blast and satisfies that anal-retentive part of me.
One of the first things I noticed was that at 8.5 A everything happens a lot faster, a LOT faster,
than at 7.5 A (duh!). For 150 grams of beans I can get a 11-13 minute roast at 7.5 A while an 8.5
amp setting is into second crack at 8-9 minutes.
I got to wondering if the large difference in roasting time would have a noticeable effect in the
taste.  Is the 8.5 A roast too fast? So I roasted two runs of Carlos Imbachi at 7.5 A and two at
8.5 A. The only control over the roast was by changing the fan speed. I'm letting them rest for
three days then I'll carefully brew one cup of each the same way and see if I like one better than
the other.
Since I just got everything needed to monitor the temperature using a thermocouple tied to a
digital monitor, I decided to see if there was a difference between the digital readout and the
analog dial thermometer that came with the machine. Not only was there a difference, at the 1-2
minute mark the difference in temperature readouts between the two was huge, as much as 60 degrees
C. The difference decreased as time went on and the dial thermometer had time to react to temp
changes. My earlier notes listing time and temperature I realize are now way off in temperature
readings.
I took a lot of notes and wrote up a pdf document with pictures, graphs, comments, and questions
and posted it to my personal web site here:http://fparth.com/misc/Roasting_notes.pdfIf anyone can help me understand the differences I'm seeing I'd really appreciate the insights.
Frank
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2) From: Robert Yoder
Thanks, Frank, for your post!
 
I am very interested to have your take on the differences in the cup between the shorter and longer roast.
 
Happy Roasting,
 
robert yoder
 
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3) From: raymanowen
"...[Why] the differences I'm seeing?"
a.) The different thermal mass of the two sensors
b.) The different heat sinking capacity of the different sensors
Other than that, it's FM.
-ro
-- 
Persist in old ways; expect new results - suborn Insanity...
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4) From: Hank Perkins
2 different thermocouples.  No differences really  Small one may react
slightly faster.
No real diferences in the thermocouples they are both "K" and meet the
K standards.
You will see differences in the readings when mounted in the roaster
the ET is located in the same airspace as the heating elements and the
BT is located inside the roasters drum with the beans.
The ET will change fast the BT will change much slower.
Hope this helps.
On Sun, Mar 13, 2011 at 4:04 AM,   wrote:
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5) From: Frank Parth
Hank,
Thanks for the thoughts. Right now both are measuring BT, so it's not the difference between BT and
ET. I think others are correct in that the difference is in how the two probes are reacting. Since
I'm now logging temps I'll just remove the dial thermometer and rely on the thermocouple plugged
into the Omega.
The next step is to link the Omega with the Artisan software and log the temperatures with the
computer. That should be a lot easier than reading the temps every 30 seconds, entering the data
into Excel and then creating a graph!
Frank
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