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Topic: profiling (was Re: Two QM3 roasts of Limoncillo (3 msgs / 75 lines)
1) From: Allon Stern
On Jan 13, 2011, at 9:50 PM, sci wrote:
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I had a thought about how to profile beans and I wanted to particularly get miKe's opinion on this....
You can watch the heat, sure, but once a profile is set in the PID, it pretty much follows that profile, but I noticed something interesting when watching a PID roast of Jimma, using miKe's profile....
with my PID unit, you can watch the % heat applied; it's interesting to watch the duty cycle of the heater at various stages in the roast. So when the roast hits a point that the beans are soaking it up, the heater works harder to hit a target temp, and when the beans are done soaking it up, the heater works less hard.
I noticed that right at the end of the profile, it was just over a hump, as it were, the duty cycle went through a peak, and had just slacked off at the end of the roast, and that got me thinking, is this one indicator of a sweet spot?
(not that all humps will indicate a sweet spot, but are all sweet spots right over a hump?)
Should be educational to set a PID to a linear roast, then graph the % heat applied vs time, alongside the temp. I'm thinking that something like this might be a good calibration roast, which you could then use to determine where to start and end each stage's ramp, as well as EOR.
Just a thought. Anyone?
(wish I had a QM3 just so I could PID it :D )
-
allon
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2) From: Robert Yoder
Hi Allon,
 
Are you talking about the Sivetz bump (hump)?  I see one of the Holy Grails as Bean Mass Temp, and this would certainly be an indicator.
 
I've been trying to get BMT readings, however tight their band, with the Behmor.  The QM3 may provide that opportunity.  
 
Happy Roasting,
 
robert yoder
 
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3) From: Hank Perkins
Allon,
I look forward to Mikes comments as well.  I have repeated that
profile, and several others with out a PID.  I do have a data logger
for temperature and it is very valuable.  One thing I do is try to
stabilize the roaster at a lower amp level than you with the temp
between 400-405f (right there at 200c).  at 90 seconds I pour on the
heat with 125g load 7.5-8 with 225g load 10.  then i flatten the temp
out when the beans get back up around 350-360f.
One thing I have noticed that I would also like Mike to comment on is
that I have gotten a sweeter cup under single origin espresso roasting
at 125g vs 225g.  Is strictly this a time function?  I then to hit C1
at 6-8 minutes on 125g and 8:30-13 minutes on 225g.  to hit  C1 in
8:30 with 225g I was running at 10a for most of that time.  The
roaster seems to change when moving from 125g loads to 225g loads.
Lastly, how slow is too slow?
The data logger with the Artisan software is a wonderful tool.  You
will find links on HB if interested.
Hank
On Thu, Jan 13, 2011 at 11:38 PM, Allon Stern  wrote:
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