HomeRoast Digest

Topic: Programable roaster (6 msgs / 109 lines)
1) From:
I have wanted to change the profile on my Coffee Kinetics roaster ever since
I got it, but lacked the knowledge to attempt it.  I did not realize what a
wealth of experience is available here on the list.
The one thing I would like to fix is the timing of the cooling cycle.  Every
so often the burner shuts down for 6 seconds, this is it's profiling method.
One of the shutdowns occurs right in the beginning of "First Crack", about
20 seconds into it.  It will drop about 20-30F bean temp, and  1st crack
will stop.  The same thing happens during "Second Crack".
I do have the schematic for the board.  The simplest fix would be a switch
to shut off the whole control board and bypass it, in order to run it
manually.  This has been my plan, but I would much prefer to change the
timer on the board so that at certain temp it stops profiling.   Or would it
be possible to install a fully programmable system so it could be set as I
Thanks for any help and advise!!
Scott Jensen
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2) From: Dan Bollinger
It would take a lot replace the circuit board with a PLC.  To change the
timer on the board would likely require reprogramming an EPROM, but there is
a chance that the timer is hard-wired and the time is set by a resistor's
value.  Installing a variable resistor instead might help you.  Running the
fan at high speed constantly would alter the profile.  The easy fix would be
to remove the fan's control from the circuit board and operate it with a
motor speed control like you would get at a hardware store to slow down a
drill.  That way you still have a controllable profile, but without the
on/off of the fan messing with the cracks.   Dan
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3) From: Rick Farris
Dan wrote:
I might be wrong, but I was under the impression that the HIP was
temperature controlled, and that the fan changing speed was it's way of
regulating the temperature.
Breaking the servo loop could lead to indeterminate operation.  As in maybe
it will heat constantly and burn up your beans, or maybe it won't heat at
-- Rick
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4) From:
The Fan is always on full speed at all times during the roast.   The
profiling is done by turning the burner on & off.   Wonder if
there is some way to modify the burner, so it can be run at different
levels, not just on and off?
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5) From: Dan Bollinger
Rick, If that's true ( I don't know), then you are right it would mess
things up.  durn!

6) From: Dan Bollinger
A more sensitive thermostat (or a programmable one) would cycle more
frequently.  You could install a variac to take care of this problem.
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