HomeRoast Digest


Topic: Hottop? (control) (6 msgs / 203 lines)
1) From: Jeffrey Pawlan
The design and production of the ten CCR systems actually cost me so much that I
made nothing. I had expected there would be a larger market, especially
by professionals but I soon found that they did not want a sample roaster
that wasn't gas fired.  As I have time and the weather accomodates, I am working
on the ultimate control system for my 1 kilo Probat. I will use much of the same
design and the math I developed (it is not ordinary PID) to control it. Thus you
can understand that I don't want to disclose the design details. I can assure
you that these were so expensive and difficult to build, that if you had the
plans you probably would not attempt it. And it requires my software.
But I want to offer a suggestion that I had brought up before and that is
affordable. This will render your hottop completely under your control.
1.  you will downgrade your hottop to manual control. Disconnect the side panel
control board and use the ribbon cable connections controlled by switches.
One each for fan, tray, blower, drum motor, and heater. The wiring connections
have been published by Randy Glass and they are simple +5v for ON and Ground for
OFF.
2.  Use an appropriately large variac (not dimmer) to control the line voltage.
3.  Get two double-kapton-covered thermocouples and glue these into the bean
chute sides using high temperature epoxy. Use a decent two channel thermocouple
readout or meter. Make one of the thermocouples go horizontally inside of the
drum and the other one should go down within the beans. Now you will be able to
read the real air temperature and the real bean temperature. The only alternate
is very very thin stainless probes. Do NOT use teflon!
4.  Control your roasts with the variac. You should always start around 120v
and should keep the voltage within the range of 90v to 125v. If you
want to shut the heater off, use the switch you wired for the heater. I find
that the roasts are always better with the fan ON and at full speed all the
time.
This will take practice, but you will achieve better roasts than the upgrade
panels from Hottop.
Regards,
Jeffrey Pawlan
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2) From: miKe mcKoffee
The notion that especially the newest KN-8828B model doesn't allow the user
full control is ludicrous IMO. Granted the heater control is 'only' in 10%
increments rather than infinite like with a variac. But you can add a variac
for even greater control without needing to hack. And the vast majority of
long time professional people using professional drum roasters believe
variable air flow is far superior in both roast control and potential cup
versus fixed air flow. The KN-8828B gives 5 fan control settings in 25%
steps (off to 100%). Plus the KN-8828B gives the user the ability to save 3
manually run roast profiles for future use which you can't do with a
straight hack.
However, all the stock HotTops use only (slow reacting) environment
temperature monitoring with no bean mass temperature monitoring at all. This
is a huge design weakness IMO. A KN-8828B would be a much better roasting
tool with added good bean mass temperature monitoring and better environment
temperature monitoring.
Pacific Northwest Gathering VIhttp://www.mcKonaKoffee.comURL to Rosto mods, FrankenFormer, some recipes etc:http://www.mckoffee.com/Ultimately the quest for Koffee Nirvana is a solitary path. To know I must">http://home.comcast.net/~mckona/PNWGVI.htmKona Konnaisseur miKe mcKoffeehttp://www.mcKonaKoffee.comURL to Rosto mods, FrankenFormer, some recipes etc:http://www.mckoffee.com/Ultimately the quest for Koffee Nirvana is a solitary path. To know I must
first not know. And in knowing know I know not. Each Personal enlightenment
found exploring the many divergent foot steps of Those who have gone before.
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3) From: Jeffrey Pawlan
Mike,
You wrote that "And the vast majority of long time professional people using
professional drum roasters believe variable air flow is far superior"
This applies to a Professional Drum Roaster such as your USRC or my Probat. Both
have far more airflow capability than is needed so we turn it down. And
adjustability is really necessary.
BUT the Hottop has a very limited and poor thermal design, most likely owing to
the combination of an underpowered heaing element, plastic body materials,
low cost construction, and requirements for obtaining UL safety approval.
So the fan is way underpowered and also the air does not flow directly through
the chamber at all. It is circulated in the space between the chamber wall and
the outer safety wall. Only a few vent slits pass a little bit of the air
through the chamber.
I have conclusively found that the airflow in the hottop is just barely enough
and sometimes I even need more so I partially open the filter in the back during
part of the roast. Under no circumstances would it help your roast to reduce the
fan in the hottop. The control of the fan speed by the new hottop programmable
panel is a marketing gimmick. No one at hottop is a coffee roaster. I know this
for a fact.
Jeffrey Pawlan
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4) From: Cameron Forde
Hi Jeffrey,
I upgraded my analog model to B and have been happy with the increase
in control that this allows.  I've found that varying the fan affects
the rate of heating especially in the early drying phase of the roast.
 WIth the fan on full I don't think that I would get near 15F/min ramp
and so I don't understand your statement, "Under no circumstances
would it help your roast to reduce the fan in the hottop."  Perhaps
your computer controller provides more current to the heater and
allows for an adequate ramp even with the fan on full, but that is not
the case for the stock machine.
Cameron
On Thu, Apr 10, 2008 at 12:39 PM, Jeffrey Pawlan  wrote:
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ceforde
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5) From: miKe mcKoffee
Cameron, you're spot on. Last Thursday did two 280 gram batches Mtn Thunder
Kona XF. With normal full on fan the profile ran long as usual coming in
438f ~17:30min LFC (just barely touching 2nd), start of 1st about 12:45.
Next batch manually toggled the fan off about 80% drying and 50% time
leading up to 1st and cut a good two minutes off time to 1st and of course
total roast time, the same automated CCR profile same bean. The CCR HT does
nothing to boost heater power. While love the repeatability of the CCR HT
running fully automated not having programable fan control was a glaring
omission IMO.
Pacific Northwest Gathering VIhttp://www.mcKonaKoffee.comURL to Rosto mods, FrankenFormer, some recipes etc:http://www.mckoffee.com/Ultimately the quest for Koffee Nirvana is a solitary path. To know I must">http://home.comcast.net/~mckona/PNWGVI.htmKona Konnaisseur miKe mcKoffeehttp://www.mcKonaKoffee.comURL to Rosto mods, FrankenFormer, some recipes etc:http://www.mckoffee.com/Ultimately the quest for Koffee Nirvana is a solitary path. To know I must
first not know. And in knowing know I know not. Each Personal enlightenment
found exploring the many divergent foot steps of Those who have gone before.
Sweet Maria's List - Searchable Archiveshttp://themeyers.org/HomeRoast/
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6) From: Cameron Forde
Hi Mike,
Along the same lines, I roast Tom's Monkey blend with the fan off
until just before 1st crack (between 12 and 13 min).  When I roast the
Donkey I've been toggling the fan on and off (at 25% about 1 min
segments) to slow the ramp to about 18F/min to give me the same
profile as the Monkey.  I guess the Donkey has lower water content and
thus lower heat capacity?  At some point I'll try reducing the heater
power to accomplish the same thing.
I hadn't realized that the CCR HT didn't allow for fan control.  Given
what Jeffrey has said on the subject I can see why he didn't bother,
though I imagine others might find it useful.
Cameron
On Thu, Apr 10, 2008 at 1:19 PM, miKe mcKoffee  wrote:
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ceforde
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