HomeRoast Digest


Topic: RK Setup (29 msgs / 1122 lines)
1) From: DeCambre.Peter
I will be out of the office starting  11/26/2002 and will not return
until 12/02/2002.
I will respond to your message when I return.
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2) From: DeCambre.Peter
I will be out of the office starting  11/26/2002 and will not return
until 12/02/2002.
I will respond to your message when I return.
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

3) From: neal prentiss
Hi all,
For those who roast with an RK, what do you use for a heat diffuser?  I've
seen several pictures of cookie sheets with tiles inside, are there other
options?
I just ordered a drum and motor from Ron, and I want to have everything
ready to put together the day my drum arrives, I can't wait:)
Also, any other suggestions or tips for putting the roaster together are
welcome. Thanks.
-Neal

4) From: Brett Mason
I found an adjustable "diffuser" at Lowes - opened it up to just the right
length for my BBQ...
Brett
On 4/14/07, neal prentiss  wrote:
<Snip>
-- 
Cheers,
Bretthttp://homeroast.freeservers.com

5) From: Eddie Dove
Neal,
I use these ... Ed Needham posted about them previously ...http://buyitnow64.stores.yahoo.net/cohotblforga.htmlEddie
On 4/14/07, neal prentiss  wrote:
<Snip>
-- 
Docendo Discimus
Home Coffee Roasting Blog and Profiles for the Gene Cafehttp://southcoastcoffeeroaster.blogspot.com/Sweet Maria's List - Searchable Archiveshttp://themeyers.org/HomeRoast/

6) From: Rich Adams
---- Original Message ----- 
For those who roast with an RK, what do you use for a heat diffuser?
The drip tray of a broiler pan.
Rich Adams

7) From: Frank Coster
This is a multi-part message in MIME format.
I use two 12" X 12" ceramic tiles 
Frank

8) From: RK
This is a multi-part message in MIME format.
I have some R&D going on with a man in Texas.
He has reported some interesting development on diffuser plates. He has =
come to believe from many lbs of testing that a diffuser that leaves =
about 2" of the burner exposed on each end, I believe he cut a cookie =
sheet to size for the diffuser.
He claims that with the combination of conduction and convection heat =
makes a difference in the cup and the flavors are more lively and =
pronounced then they are using a plate, or similar diffuser that covers =
all of the burner like I am using now. I use a 12g. cold rolled steel =
plate, leaving only about 2" all around for air movement.
It has reduced the time of the roast about 1 min or allows for a =
slightly lower heat to hit the target roast.
Lower heat also will save on propane and adds another dimension to the =
roasting process.
I have not had a chance to try this myself or cup any coffee he has =
roasted using this method.
Just thought I would mention it, if anybody else might want to try it =
and see how it compares with a larger plate covering the entire burner =
system.
RK

9) From: Les
Ron,
I talk to the guy in Texas and am running a similar setup with the same
results.
Les
On 4/15/07, RK  wrote:
<Snip>

10) From: Bob
This is a multi-part message in MIME format.
This is interesting. I followed RK's advice when assembling my diffuser =
and has worked well for me. But, if it could be better, am all ears. 
Don't understand how the beans know difference between convection and =
conduction heat, especially when inside a drum. Any of our engineer =
types want to chime in?
Cutting my diffuser down would not be a chore, but to return to original =
size would be! Need to understand the physics first.
Bob

11) From: RK
This is a multi-part message in MIME format.
This is the same guy Les, as he has told me he has conversed with you =
about the cupping results.
RK

12) From: Aaron
while it is true in one aspect that heat is heat. it's not so much the 
beans knowing the difference, but more, the efficiency or thoroughness 
of the heat getting to your beans.   conduction you are relying on the 
heat transferring from the hot surface of the drum to the beans and is 
probably only going to get the beans in the layer closest to the drum 
metal itself.. beans not touching the drum are not going to conduct the 
heat to them..   Convection now it's the drafts or hot air that is 
blowing / moving and bringing the heat with it.... this would be a more 
thorough form of heat id' say as it should be able to penetrate deeper 
into the bean mass and bring the heat with it.
Between the two, you should have a very good even roast if all goes 
well.  oh and lets not forget radiant heat as well...
whatever method happens, getting a good heat transfer and most 
importantly an even heat transfer is the most important thing.... the 
diffuser tends to eliminate 'hot spots' that might have a very small 
area of very high heat (ie right over the burner), and helps distribute 
the heat more evenly.
aaron

13) From: derbyrm
This is a multi-part message in MIME format.
A total analysis would take many pages, but, some thoughts to ponder:
  -  radiant heating -- infrared energy from the flame or radiating =
element heats the side of the bean pointing at the heat source, the rest =
of the bean depends on the heat flowing thru the bean -- darker beans =
get more rapid heating, shiny light colored beans get little heat
 - conductive heating -- only that point on the bean that's touching a =
hot object gets heated, the rest of the bean depends on the heat flowing =
thru the bean -- not dependent on bean color -- chaff or charring may =
impede heat flow -- "hot object" may be another bean that's at a higher =
temperature
 - convective heating -- the hot air carries the heat to all sides of =
the bean -- lower temperature allows more penetration of the heat into =
the bean, less surface charring -- slower cooking -- not so dependent on =
bean color, but bean texture may influence rate of heating (rough =
surface means more contact with the hot air molecules)
Roger
derbyrm http://home.insightbb.com/~derbyrm

14) From: Coffeenut
This is a multi-part message in MIME format.
Hey Guys,
I'm curious about something and want to better understand the setup you're
describing.  
Is there also some gap being allowed between the sides of the burners and
the wall of the grill or is that area fairly closed with only the 2" on each
end open?
This whole thing has been something I've questioned and played with too.
Currently, I have the top, sides and ends over my burners covered with those
ceramic diamond briquettes (no gaps anywhere), although there are minor air
gaps between the briquettes themselves.  I used to have gaps around the
sides of the burner areas open about 1" and on the ends about 2".  However,
I was concerned that the rush of hot air coming up the sides might be
interfering with my temp probe readings near the drum.  So, I basically
closed those gaps.  This deflection config has been working fine for me with
the only difference noted in the time it takes for grill to reach startup
temps (takes a few minutes longer since I closed the gaps).  It seems once
the ceramic briquettes are heated, they do a nice job of providing a stable
temp for the roast.
Rick

15) From: Ed Needham
I've roasted without any diffusion at all and the coffee still comes out 
roasted well.
There's much less room for error though without the safety net of some sort 
of diffusion.  But too much diffusion causes other problems, one of which is 
wasted heat.  When I had most of the bottom covered with a thick steel 
griddle device for diffusion, it took forever to get the upper roast chamber 
up to temperature and the coffee came out tasting dull and boring.  I hit 
all the roast marks, but the static roaster heat did not bring out the 
flavors as well as when the beans had a more aggressive connection with the 
heat source.
I've had the greatest success with the porous diffusion tiles and leaving 
airspace on both ends like you mention.  About 3" on each end for convection 
currents to easily flow.  It also allows faster heat response time if I need 
to quickly adjust the heat.
*********************
Ed Needham
"to absurdity and beyond!"http://www.homeroaster.com(include [FRIEND] in subject line to get through my SPAM filters)
*********************

16) From: Coffeenut
Ed,
How about the sides of your burners and those diffusion tiles you are using.
Do you have the tiles basically covering any side gaps between the sides of
the burners, or do you have a gap there too? 
I may go back to having the gaps because of your points.
Rick

17) From: Ed Needham
My burner is about 3" wide by 14"~ long with rounded ends.  I bought a wire 
grate with a sheet metal piece directly over the burner that is about 4" 
wide.  I have the 3x3 perfed ceramic heat tiles lined up on each side of 
this metal piece, but instead of going fully side to side, I leave about 3" 
on each end.  Basically I have tiles running about the length of the 
roasting drum, and maybe a little more.
Here's an old picture of my setup showing the metal strip and the tiles on 
both sides.http://www.homeroaster.com/F1180150.jpgthis does not show the 3" space on both ends because back when this pic was 
taken I had them fully side to side.  The terra cotta tile is under my temp 
probe to protect it from direct heat.
*********************
Ed Needham®
"to absurdity and beyond!"http://www.homeroaster.com(include [FRIEND] in subject line to get through my SPAM filters)
*********************

18) From: Tom Ulmer
This is a multipart message in MIME format.
Why would you want to get bogged down in the heat energy, work, and the
thermal properties of the components in the system(s)?
What I think I'm hearing is that by reducing the size of the diffuser along
either end of the burner  there is more heat energy available in the area
above the diffuser and that folks have observed this to be beneficial to the
roast results. 
Convection already occurs as the drum spins to some degree and the hotter
air moving into the chamber above the diffusing plate at either end may
create other areas of convection that allow more efficient heat distribution
to the drum.
Of course the initial results are hearsay and there has only been  one
second so the motion is still with your beans, heat, and of course
commentary.  
From: homeroast-admin
[mailto:homeroast-admin] On Behalf Of Bob
Sent: Sunday, April 15, 2007 6:44 PM
To: homeroast
Subject: Re: +RK Setup
This is interesting. I followed RK's advice when assembling my diffuser and
has worked well for me. But, if it could be better, am all ears. 
Don't understand how the beans know difference between convection and
conduction heat, especially when inside a drum. Any of our engineer types
want to chime in?
Cutting my diffuser down would not be a chore, but to return to original
size would be! Need to understand the physics first.
Bob

19) From: Aaron Gee
I have a 46,000+ btu grill and I have noticed that I have some pitting on some of the roasted beans..... I too am new to this so I was wondering if these pits are actually beans that have been burned.
   
  In a 3 pound batch I get about a cup full of beans that have pits.
   
  I get to first crack in just under 11 1/2 minutes and I have heat diffusers. I heat up my grill to 500 degress for about 10 minutes before I insert my drum. I then turn down the burners to 3/4 of their potential after about 4 minutes and then turn down the burners again once first crack is starting to 1/2 power and then pull the drum at the start of second crack. Total roast time is between 16 and 18 minutes.
   
  Any Suggestions?
Aaron  wrote:
  while it is true in one aspect that heat is heat. it's not so much the 
beans knowing the difference, but more, the efficiency or thoroughness 
of the heat getting to your beans. conduction you are relying on the 
heat transferring from the hot surface of the drum to the beans and is 
probably only going to get the beans in the layer closest to the drum 
metal itself.. beans not touching the drum are not going to conduct the 
heat to them.. Convection now it's the drafts or hot air that is 
blowing / moving and bringing the heat with it.... this would be a more 
thorough form of heat id' say as it should be able to penetrate deeper 
into the bean mass and bring the heat with it.
Between the two, you should have a very good even roast if all goes 
well. oh and lets not forget radiant heat as well...
whatever method happens, getting a good heat transfer and most 
importantly an even heat transfer is the most important thing.... the 
diffuser tends to eliminate 'hot spots' that might have a very small 
area of very high heat (ie right over the burner), and helps distribute 
the heat more evenly.
aaron---------------------------------
Ahhh...imagining that irresistible "new car" smell?
 Check outnew cars at Yahoo! Autos.

20) From: Floyd Lozano
Check out the degree of roast pics on SM site.  Those 'pits' may be beans
that have blown shrapnel away because they have reached 2nd crack.
-F
On 4/16/07, Aaron Gee  wrote:
<Snip>

21) From: Joe Screnock
I've been considering a change to my RK setup and including some sort of 
heat diffuser, but I don't know what it will gain me.
Ed's burner setup (as he described below) is quite different from mine. 
  I have a Brinkman Pro 4310 which has three separate burners that run 
perpendicular to the grill, not parallel.  The grates that cover the 
burners are heavy steel and have, by my recollection, more than 50% of 
the area "solid" rather than "open".  (I don't have the grill in front 
of me, so I'm going by memory - a very dangerous thing indeed.)
With such a setup, I really don't see the benefit of additional 
diffusing.  Does anyone with a similar burner configuration have any input?
Also, I don't remember the BTU's of this unit (43K sticks in my mind 
though) but I know I have a hard time with small (less than 2 pounds) 
batches.  I roasted 2 lbs of Kona this past weekend and once first crack 
approached, I couldn't keep it under about 490 with all burners on.  I 
dropped one burner but was afraid of an un-even roast.  (I suppose a 
good case for a diffuser, no?)  The roast turned out great, much to my 
relief.  I really hate to mess up $40 worth of coffee.
Take care and God bless.
Joe
Ed Needham wrote:
<Snip>
-- 
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22) From: Sue
Joe,
I also have a Brinkman grill. I'm not sure of the model as I am not at home.
I have 3 burners and 40something BTU's, I think 43 or 45K (bought at Walmart
last year) My grill also has heavy, tented, metal covers over the burners. I
was thinking the same thing about adding any heat diffusers. I don't have
any trouble getting the heat where I want it, pretty much when I want it.
There is very little variation in the heat other than from what I do. I
think the metal burner covers help tremendously. I aslo think the double
walled construcyion of the grill helps also. I have grilled in some pretty
cold and windy northern Michigan winters without any difficulty. I usually
roast 3-4 pound batches, sometimes just 1 or 2 pounds though. I love my RK
drum (sounds like a bumper sticker) set-up!
On 4/17/07, Joe Screnock  wrote:
<Snip>

23) From: RK
This is a multi-part message in MIME format.
<Snip>
home. I have 3 burners and 40something BTU's, I think 43 or 45K (bought =
at Walmart last year) My grill also has heavy, tented, metal covers over =
the burners. I was thinking the same thing about adding any heat =
diffusers. I don't have any trouble getting the heat where I want it, =
pretty much when I want it. There is very little variation in the heat =
other than from what I do. I think the metal burner covers help =
tremendously. I aslo think the double walled construcyion of the grill =
helps also. I have grilled in some pretty  cold and windy northern =
Michigan winters without any difficulty. I usually roast 3-4 pound =
batches, sometimes just 1 or 2 pounds though. I love my RK drum (sounds =
like a bumper sticker) set-up! 
Sue:
I think the Brinkman grill is good just the way it comes, it covers the =
burners enough to keep the flames away from the drum but allows enough =
space for air movement . I often recommend the Brinkman to those who =
ask. 45K in the tub and 12 on the side burner, low hood design and all =
for $198 at Wal-Mart.
RK

24) From: john nanavati
does it matter what metal you use for a diffuser?
On 4/17/07, David Echelbarger  wrote:
<Snip>

25) From: john nanavati
I would expect that a cast iron deflector might be more desirable to
aluminum or other.
On 4/18/07, David Echelbarger  wrote:
<Snip>
 I
<Snip>
y in
<Snip>
l;
<Snip>

26) From: John Moody
It serves as a deflector, (changes airflow) diffuser, (spreads heat)
radiator (infrared heating source) and damper (stores heat).  Aluminum
spreads better but stores a little less.  Aluminum radiates less when it’s
clean.  Aluminum would seem to be a better choice, but it is more expensive.
The RK Drum seems to be very tolerant of setup, so unless you have a problem
achieving the temperature profile you want, I would not worry about the
material or thickness of your deflector.
John

27) From: john nanavati
good to know. thanks.

28) From: Mark Bartkowiak
This is a multi-part message in MIME format.
"does it matter what metal you use for a diffuser?"
Mercury would be a bad idea (it keeps falling through the grate), sodium =
might be bad as well, 
All kidding aside, like cookware, cast iron would take longer to heat up =
but would release the heat slower, evening up any temperature =
fluctuations. Aluminum would do the same to a lesser degree. Cast iron =
might be less responsive to your temperature ramp ups and cause some =
lagging.
Mark B. Midland, NC

29) From: RK
This is a multi-part message in MIME format.
Cold Rolled Steel is relatively cheap compared to other metals, can be =
found at any welding shop or fabrication shop. These shops usually have =
drop from jobs they do, drop is the left over metal from a job. and will =
cut and sell you what you need fairly cheap and maybe free in some =
cases.
I have a 12 gage piece that I have been using for 3 yrs or 4 years so it =
is durable.
Do not use galvanized metal. ( fumes are toxic)
RK


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