I consider myself an experienced roaster. After seven years of
roasting, I’m comfortable with my baseline knowledge and my
understanding of the roasting process. However, I’m finding that
today’s coffee roasting environment is one of constant change.
The craft is being immersed with science, offering us new ways to
unravel the mysteries of roasting, such as what really happens to
the green coffee during the roasting process.
The primary concepts I learned in Coffee Roasting 101 are
important in understanding the fundamentals of the roast, and
it’s this base knowledge that gives me a level of comprehension
as I turn my focus to new ideas and concepts of control like PID
controllers.
For years, I used a digital timer and temperature probe to
achieve consistency in my roast profiles and had satisfactory
results. But I found that I had to move out of my comfort
zone of familiar techniques and
terminology to learn the new skill
of controlling the roast with PIDs.
While this was an intimidating
endeavor, my newfound roasting
skills and working knowledge of
PID controllers (although limited)
has been rewarding and exciting.
I feel that learning the scientific
language and mastering the basics
of PID controllers provided me
with a new level of expertise. When
I combine this new science with my
craft, I have a new roasting tool that
helps achieve a controlled path to
the completion of each and every
roast.
Today, I control my roaster
environment and the manner in which my roasts progress to the
desired drop point through the logic of the PID controls. This
allows me to look beyond time and temperature as the main
components of the roast profile. With the PID, the S-curve
becomes my tool for discovering the best path to a desired roast.
To determine the most desirable roast profile, I cup various
profiles of the same coffee roasted to the same degree. I alter the
S-curve of each trial roast for an aggressive start or a gentle curve,
for a shorter or longer rest period. When I cup the varying profiles
against one another, I find that the path taken to the drop point
changes the cup characteristics of each coffee, that the path itself
is as critical as the time and final temperature.
Initially I was overwhelmed with the entire concept of control
and PID and, had I been a rookie, it could have been setback for
me. Still, I attempted to break the process down to its simplest
form, making this foreign concept not quite so overwhelming.
I learned that the P of PID means proportional; I find it’s easier
to remember as “power.” The amount of power I apply to the roast
to reach the desired temperature in a pre-designated time frame.
The higher I set the P value, the faster the temperature climbs. If
my initial P settings are too high, the profile path is overshot and
it’s difficult to slow the roast down and regain control.
Once I get the P set so the roasting profile is followed
consistently, I rely on the I, or integral, setting to fine-tune the
roast profile. The I setting provides output boosts to keep the
I consider myself an experienced roaster. After seven years of
roasting, I’m comfortable with my baseline knowledge and my
understanding of the roasting process. However, I’m finding that
today’s coffee roasting environment is one of constant change.
The craft is being immersed with science, offering us new ways to
unravel the mysteries of roasting, such as what really happens to
the green coffee during the roasting process.
The primary concepts I learned in Coffee Roasting 101 are
important in understanding the fundamentals of the roast, and
it’s this base knowledge that gives me a level of comprehension
as I turn my focus to new ideas and concepts of control like PID
controllers.
For years, I used a digital timer and temperature probe to
achieve consistency in my roast profiles and had satisfactory
results. But I found that I had to move out of my comfort
zone of familiar techniques and
terminology to learn the new skill
of controlling the roast with PIDs.
While this was an intimidating
endeavor, my newfound roasting
skills and working knowledge of
PID controllers (although limited)
has been rewarding and exciting.
I feel that learning the scientific
language and mastering the basics
of PID controllers provided me
with a new level of expertise. When
I combine this new science with my
craft, I have a new roasting tool that
helps achieve a controlled path to
the completion of each and every
roast.
Today, I control my roaster
environment and the manner in which my roasts progress to the
desired drop point through the logic of the PID controls. This
allows me to look beyond time and temperature as the main
components of the roast profile. With the PID, the S-curve
becomes my tool for discovering the best path to a desired roast.
To determine the most desirable roast profile, I cup various
profiles of the same coffee roasted to the same degree. I alter the
S-curve of each trial roast for an aggressive start or a gentle curve,
for a shorter or longer rest period. When I cup the varying profiles
against one another, I find that the path taken to the drop point
changes the cup characteristics of each coffee, that the path itself
is as critical as the time and final temperature.
Initially I was overwhelmed with the entire concept of control
and PID and, had I been a rookie, it could have been setback for
me. Still, I attempted to break the process down to its simplest
form, making this foreign concept not quite so overwhelming.
I learned that the P of PID means proportional; I find it’s easier
to remember as “power.” The amount of power I apply to the roast
to reach the desired temperature in a pre-designated time frame.
The higher I set the P value, the faster the temperature climbs. If
my initial P settings are too high, the profile path is overshot and
it’s difficult to slow the roast down and regain control.
Once I get the P set so the roasting profile is followed
consistently, I rely on the I, or integral, setting to fine-tune the
roast profile. The I setting provides output boosts to keep the
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