HomeRoast Digest


Topic: Installing a PID in a RK Drum set up (30 msgs / 765 lines)
1) From: True, Dennis W. FC1 (CVN69)
This is a multi-part message in MIME format.
Ok I have a question: If I were to install a PID in a Grill/RK Drum set
up what is the preferred method? 
All I really know is it should be as close to the same height as the
bean mass and as close as I can get it to the drum. 
Dennis

2) From: Dan Bollinger
This is a multi-part message in MIME format.
Installing a PID in a RK Drum set upI suspect you meant the location of =
the thermocouple, not the controller itself! I think your location would =
work, but best would be inside the bean mass.
Dan

3) From: True, Dennis W. FC1 (CVN69)
This is a multi-part message in MIME format.
yes thermo coupler does anyone have any ideas about mounting one in the
drum itself?
 
 
V/R, 
FC1(SW/AW) Dennis W. True 
"Life Liberty and the pursuit of all who threaten it..."

4) From: Robert Avery
This is a multi-part message in MIME format.
MessageNot sure about the application, but ... I just recently received =
a thermal sensor that has a remote reader for cooking Chicken, Steak, or =
a Turkey with on the grill. I haven't thought about it a whole lot .. =
but it would seem you could mount it on the drum with the probe in the =
beans. Mine has a remote receiver that I take in the house and an alarm =
goes off to tell you when temp. has been reached up to 392 degrees F. =
Here is the item if one is interested. http://www.office1000.com/discount/thermometer-culinary.html

5) From: miKe mcKoffee
This is a multi-part message in MIME format.
Wouldn't work for various reasons. (I have a couple same/different brand
units.) The probe is plugged into (or hard attached to) a sending unit which
is not designed for high heat. The drum turns so the lead would get wrapped
up since sending unit would be external. The maximum temp is 392f which is
too low for end of coffee roasting purposes.
 
Pacific Northwest Gathering VIhttp://home.comcast.net/~mckona/PNWGVI.htmKona Kurmudgeon miKe mcKoffee
URL 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/ 
From: homeroast-admin
[mailto:homeroast-admin] On Behalf Of Robert Avery
Sent: Saturday, July 21, 2007 11:53 AM
Not sure about the application, but ... I just recently received a thermal
sensor that has a remote reader for cooking Chicken, Steak, or a Turkey with
on the grill. I haven't thought about it a whole lot .. but it would seem
you could mount it on the drum with the probe in the beans. Mine has a
remote receiver that I take in the house and an alarm goes off to tell you
when temp. has been reached up to 392 degrees F. Here is the item if one is
interested. http://www.office1000.com/discount/thermometer-culinary.html 

6) From: True, Dennis W. FC1 (CVN69)
This is a multi-part message in MIME format.
ok any thing out there that will work? 
or is everybody just mounting them to the grill?
 
Dennis
V/R, 
FC1(SW/AW) Dennis W. True 
"Life Liberty and the pursuit of all who threaten it..."

7) From: Dean
you could use a slip ring set for the wires, run the TC along the shaft, 
pick a spot to place it in the air inside the drum.  don't forget that 
it gets hot in there--fiberglass of other hi-temp insulator on the 
wire.  remote the display thru the slip rings
Dean
in da weeds
True, Dennis W. FC1 (CVN69) wrote:
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8) From: Rich
Slip rings and thermocouples do not play well together.  You will have terrible accuracy and a 
maintenance headache.  The do not function well in an ideal environment.  The inside of a propane 
fired grill full of roasting coffee smoke at 500 degrees is not an ideal environment.
On Sat, 21 Jul 2007 17:11:35 -0500, Dean wrote:
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<Snip>http://sweetmarias.com/maillistinfo.html#personalsettings

9) From: True, Dennis W. FC1 (CVN69)
I take it that mounting to the inside of the grill is the accepted
method any placment suggestions?
Dennis
V/R,
FC1(SW/AW) Dennis W. True

10) From: miKe mcKoffee
The challenge of how to measure bean mass temp in a drum with totally closed
design isn't limited to the RK, most seem to be built that way including the
coming Behmor 1600. IIRC Ed IS measuring bean mass temp in his grill/drum
roaster, but he built his own drum designed with open end.http://home.comcast.net/~mckona/PNWGVI.htmKona Kurmudgeon miKe mcKoffee">http://www.homeroaster.com/F1180150.jpgPacific Northwest Gathering VIhttp://home.comcast.net/~mckona/PNWGVI.htmKona Kurmudgeon miKe mcKoffee
URL 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/
<Snip>

11) From: Rich
Each grill setup is different.  Pick a location where the IR energy will not directly hit the TC.  If the TC 
can "see" the flame it will be very unreliable.  Depending on the venting and shielding of the grill, 
think about somewhere in the same horizontal plane as the beans.  Black objects radiate energy, 
watch out for the hot ones.
On Sat, 21 Jul 2007 19:00:35 -0400, True, Dennis W. FC1 (CVN69) wrote:
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<Snip>http://sweetmarias.com/maillistinfo.html#personalsettings

12) From: Michael Dhabolt
The only method of TC placement in a drum that I am familiar with is
with an open ended drum such as a commercial roaster or the Alpenroast
uses - pretty easy to position the TC tip in the bean mass with that
drum configuration.  If using an RK or similar setup, I would expect
that placing the TC at bean height with the tip fairly close to the
drum - probe going thru an appropriately sized brass fitting with a
compression ring mounted thru the side of the grill housing.  The
temperature indication would be relative and effectively the same as
other BBQ / drum roasters see.
IMHO the TC and PID are do-able, the problem then becomes a gas valve
that can be controlled by the PID.  You would want to option the PID
with an analog signal output rather than the off/on signal usually
used to control a Solid State Relay as is common with electric heat
source roasters.  Finding an appropriate valve and/or valve operator
first and then acquire a PID with the correct type of output signal to
drive the valve (there are several different common control signals).
Mike (just plain)

13) From: Michael Wascher
So the solution would be to make a portion of the drum not rotate?!
Make one of the end-plates fixed & run the probe through that. Have the drum
rotate such that the inside of the drum bears on the outside of the fixed
end plate.
--MikeW
On 7/21/07, Rich  wrote:
<Snip>
-- 
"We are confronted with insurmountable opportunities." --Walt Kelly

14) From: Rich
Here is the valve...  URL: http://www.cajun-outdoor-cooking.com/sepasttecova.htmlOn Sat, 21 Jul 2007 16:31:56 -0700, Michael Dhabolt wrote:
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<Snip>http://sweetmarias.com/maillistinfo.html#personalsettings

15) From: Michael Dhabolt
I would like to add:
If anyone finds an affordable gas valve and/or valve/operator I'd sure
like to hear about it.
During one of my recent projects with a commercial gas fired fluid bed
roaster, I couldn't firgure out a way of solving this problem without
spending in the $800 range for just the valve and operator.  I can't
help but think that some enterprising individual will stumble upon a
considerably more affordable solution - sooner or later.
Mike (just plain)

16) From: Robert Avery
This is a multi-part message in MIME format.
MessageJust for info ... I often wondered why you couldn't use the brush =
contact system to transfer the signal. Its purely an electrical signal. =
Then you could fasten the drum probe to the main stator that would =
revolve and the brush type contact would be stationary and provide =
continuity for the sending unit that would be placed outside the roaster =
.... ????? Just thinking. Later, Bob

17) From: Dan Bollinger
<Snip>
Mike, I'm sure you meant a proportional valve but I'd like to offer a practical 
alternative. Use two gas jet orifices to feed one, large burner. One jet is 
always on and is set to about the steadystate for the roaster. That is, about 
what the roaster is losing to the environment at roasting temps. Then, the PID 
turns the second jet on and off using a small solenoid valve. With a PID set on 
a short cycle it would be a viable solution. And, with both feeding the same 
burner you don't have to worry about a second burner lighting.
Dan

18) From: True, Dennis W. FC1 (CVN69)
This is a multi-part message in MIME format.
Man can I pick them or what...LOL
 
my questions seem to keep this list in business!!!!
Thanks for all the advice I have a few "nuke sailors" around and I'm
going to ask them what they think about this 
 
Anybody thougth about a temp resistant remote unit you could mount to
the end of the drum and transmit the data to the control unit?
 
 
 
Dennis
V/R, 
FC1(SW/AW) Dennis W. True 
"Life Liberty and the pursuit of all who threaten it..."

19) From: Michael Mccandless
Use of brush contacts would add two more thermocouples.
The resulting measurement would be very unreliable, although
possibly useful as a relative indicator of bean temp.
McSparky
On 7/21/07, Robert Avery  wrote:
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20) From: Michael Dhabolt
Michael Wascher wrote:
<Snip>
This seems like a reasonable solution.  How could it be implemented in
a configuration that still allows quick drum removal (RK style) to
unload the beans at end of roast?  Or: is there another method of
unloading that should be considered?
Mike (just plain)

21) From: Michael Wascher
I took a look at one of these a while back. It doesn't get hot enough to
roast. IIRC the highest setting was 400F.
On 7/21/07, Rich  wrote:
<Snip>
-- 
"We are confronted with insurmountable opportunities." --Walt Kelly

22) From: Michael Mccandless
I've tossed this around quite a bit.
One possibility would be to have a hollow shaft & run a rigid
conduit through containing the TC wire.
A Stainless probe might be bent to reach the bean mass &
somehow held  in place.
McSparky
On 7/21/07, True, Dennis W. FC1 (CVN69)  wrote:
<Snip>

23) From: Michael Wascher
The other end could still use a shaft. Remove from the other end. You'd have
to keep it tilted, but it should be doable.
On 7/21/07, Michael Dhabolt  wrote:
<Snip>
-- 
"We are confronted with insurmountable opportunities." --Walt Kelly

24) From: Michael Dhabolt
Dan Bollinger wrote:
<Snip>
Sounds feasible - Gonna take some time and effort to build and test.
Nuking the idea a bit....why stick to just two.....several could be
opened in sequence by using the alarm outputs from the PID (step
change as the heat requirements increase during the roast).  Keep one
small orifice as the control element between step changes.  I'm not
knowledgeable enough about BBQ/drum roasting to know if this would be
advantageous or not.
I usually order my PIDs with three alarm outputs and have recently
been playing with using these outputs to sequence a load resistor into
the fan control circuit (slows fan) at a given location during the
profile (less air flow required after beans become lighter).
Mike (just plain)

25) From: Michael Dhabolt
Robert Avery wrote:
<Snip>
Bob,
You are in good company, folks have been trying this for over a
century (TCs are old technology).  A couple of other replies in this
thread have pretty well exercised the problems you run into with
brush/slip ring conductance of a TC signal.  Minuscule signal level
and every time you change conducting material you effectively add a
new TC junction into the mix.
Mike (just plain)

26) From: Dan Bollinger
<Snip>
More than two seems overly complex, to me.
Using a burner that is always on and using a PID to on-off a second orifice 
means your response time is going to be very fast. Faster than a bare nichrome 
wire coil. I know, I've measured it. That means that your PID should be able to 
control the heat within a degree or two.
Dan

27) From: Michael Dhabolt
Dan Bollinger wrote:
<Snip>
You are probably right.  I don't have any experience or knowledge
concerning how the heat requirements change during the profile with a
roaster of this type.
Mike

28) From: Dean
You do create additional junctions at each connection, but they cancel 
each other out if the slip ring is at a uniform temperature.
chromel---copper--\o\--copper---chromel
alumel---copper--/o/--copper---alumel
for a K couple
as long as the junctions are all at the same temperature they add & 
subtract resulting in no change in reading. 
you can use a Mercotac slip ring ($$) or find another one or make your 
own.  I've done it, not recently.  It works.
the key is "the same temperature" and of course low contact resistance.  
The Meter >should< be a high impedence input so the wire & slip ring R 
is less of a problem. 
The main problems are these two--cheap meters are pretty low-accuracy, 
and couple placement is a challenge.
But I suggest that having a bad indication of the temperature (which 
should be repeatable, if not terribly accurate) is better than an 
uninformed guess.
Dean
in da weeds
Michael Dhabolt wrote:
<Snip>

29) From: John Moody
You can buy one from Scott; nice design.http://scott.marquardt.googlepages.com/openskyroasterJohn

30) From: Homeroaster
I posted this poorly done sketch once before but here it is again for an 
alternate drum design with the ability to insert a probe.http://www.homeroaster.com/drumtemp.jpgIt is essentially two drums fastened together with u-shaped internal 
brackets that allow an 1/8" space for a fixed thermal probe to be inserted 
into the beans.
*********************
Ed Needham
"to absurdity and beyond!"http://www.homeroaster.com*********************


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