[Homeroast] Ruminations on the QM3 and testing results

Frank Parth fparth at mac.com
Sat Mar 12 10:37:54 CST 2011

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

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.pdf

If anyone can help me understand the differences I'm seeing I'd really appreciate the insights.


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