HomeRoast Digest


Topic: deidrich drum steel (BBQ Roaster) (60 msgs / 1484 lines)
1) From: Scott Jensen
Mabey Charlie or someone with a better memory than mine can chime in here.
While at the Diedrich seminar I remember Steven talking about their drums.
I think they use a high carbon steel??  The heat transfer properties of the
steel they use is much better -that's the reason I remember him giving.  I
do remember the talk about how they use that particular steel for that very
reason, just don't exactly remember which steel it is.  I'm sure it's not
stainless- anyone else remember?
Scott

2) From: floyd burton
While visiting Doug Zell at Intelligentsia we learned they like a very old
German roaster cause it has cast-yes get this cast drums.  Now a casting
that large and thin is not an easy thing to do.  Blew me away when they told
me the drums were cast-would have lost a bet on that one.  Don't know why
they would go with high carbon steel-kinda of nasty stuff-would guess low
carbon cold rolled-simply cause it has a nicer finish.  Don't think high
carbon would be any benefit-could well be wrong.  But cast iron has
legendary conductive properties-many cooks still swear by their "spiders"
and say the modern very pricey cookware does not even approach the even
heating properties of their old cast skillets.  The roasters at Doug's I
thought were Hothow's-but that's not it -Jim S knows.

3) From: Oaxaca Charlie
--- Scott Jensen  wrote:
<Snip>
 He said high carbon steel, for sure. Their roasters use the
conductive heat from the drum as a major roasting
component.(refractive and convective heat in there too) I prefer
not having to deal with that. If I was roasting 20 lb. batches
all day then I'm sure it would save a lot on fuel and time to
have thick and heavy steel. For 1 to 5 lb. batches it's more to
heat up before you can start roasting, and more to lift while
hot to dump the beans.
Charlie
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4) From: Dan Bollinger
I cannot think of any material quality that would justify the cost of high
carbon steel in a roaster drum.  Most mfgr. is done with low carbon steels,
especially if any sort of forming is needed like rolling.  As steels add
carbon they also add other metals including chromium which resists
corrosion.  Perhaps they are using high carbon, steel not for the carbon,
but for another additive.  But, I doubt it, it sounds like marketing BS to
me. I'll see if I can find the thermal qualities for carbon steel.  In the
meantime if someone learns what the name or code is for the steel I'll look
it up. With all our talk about making roasters it might be important.  Dan
<Snip>
the
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very
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steel
<Snip>
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5) From: Jim Schulman
On 11 Feb 2003 at 18:41, floyd burton wrote:
<Snip>
1940s and 50s vintage Gothot roasters with cast 
iron drums. Don't know about the fabrication 
process; perhaps two welded half pipes? Makes the 
ideal cooking surface, imo, except for the 
unfortunate darkening of light colored acidic 
foods. I guess that's not a problem with coffee 
beans.
Jim
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6) From: floyd burton
Yup they are Gothot's, not Hothow's-still a cooool name.  Here is a web site
that has some info on what various carbon levels of steel are used for what
apps.  Looks like the high carbon stuff is used for tensile strength
apps-wire and the like.  Med carbon for strength-railroad axels and the low
carbon for rolled sheet-don't think the heat transfer properties of steel
with .3% carbon is very different than that of steel with 1% carbon which is
high carbon steel.  Cast is a very different structure though-I think cast
iron is very difficult to weld-most castings are in one piece which makes
those Gothot's soo coool.  Easy to break also.http://www.key-to-steel.com/Articles/Art62.htm

7) From: Jim Schulman
On 11 Feb 2003 at 19:26, floyd burton wrote:
<Snip>
So one-off molds, that would have to be broken to 
get the drum out? That would be very cool
Jim
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8) From: Ed Needham
As Butch now knows...weight is a pretty important consideration...
Ed Needham
To Absurdity and Beyond!http://www.homeroaster.com
ed
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9) From: Tom & Maria (SweetMaria's Coffee)
I am not a metals expert, but. ...People love the old Probat cast 
drum roasters because they are such incredibly high quality castings 
-very thick, very precise. The Jabez Burns are nowhere near as thick, 
and they have a lot more porousity. The Diedrich is high carbon steel 
but not stainless. Mine certainly wasn't stainless -it looked like 
mild steel to me. Thin stanless sheet doesnt have great thermal 
properties for roasting, but its what you want for a perforated drum 
roaster. What I cant remember is what the old Gothot roaster I used 
was -definitely perforated drum with gravity chaff separation and 
overhead burners in a shroud. But I can't recall if I ever noticed 
how thick the perforated material was or what it might have been made 
out of... That roaster was circa 1910! So in terms of having a 
roaster with great conductive capabilities, maybe a piece of old 6 to 
10" cast vent pipe would be good! Of course, I think that was sealed 
with lead ...not good.
Tom
--
                   "Great coffee comes from tiny roasters"
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10) From: Rick Farris
Floyd wrote:
<Snip>
Legendarily *poor* conductive properties, you mean.  Cast iron is one of the
poorest heat conductors used for modern cookware.  Aluminum is an order of
magnitude better, and copper is three times better than that.
The reason cooks like cast iron is because it *holds* heat well.  (Things
that conduct heat well cool off (or heat up) very quickly.)
As for even heating, there are few metals worse than cast iron.  That's why
you need to put cast iron pans on the stove and leave them for a while
before you cook in them -- to give the heat time to spread around the pan.
-- Rick
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11) From: Rick Farris
Jim wrote:
<Snip>
Ever tried 2.5mm copper?
-- Rick
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12) From: floyd burton
Thanks for pointing out the faults of cast iron-but ya know I will still
only use AL pans to boil water-guess what I really like about cast iron
skillets is they tend to be easier to cook with-less burning-still will keep
my cast iron pots.
Oh-does high carbon steel have better thermal properties than low carbon
steel and can high carbon steel be easily converted into sheet or roll forms
for building things like drums.  Can't figure out why Diedrich would use
high carbon steel for their drums-but in a previous post Tom said they did
use high carbon steel.
Also can you weld cast iron-thanks

13) From: Dan Bollinger
Cast iron is not easily welded.  No one would weld CI in a production
setting and is limited to repairs.
I did some searching on the thermal qualities.  Specific heats are about the
same for all ferrous metals.
Heat transmission is telling.  Like Rick said, CI is a poor conductor and so
is hard steel.  Hardened steel is made from medium and high carbon steel. It
is unclear if annealed high carbon steel will have the same value as
hardened high carbon steel shown below. I was surprised to see so much
difference between mild and carbon steel.
Cast Iron = 1.0 BTU/ft2 Hr F
Mild Steel = 1.4
Hard Steel = 0.8
Copper = 4.5
Heat Radiation is different, too
Cast Iron = 0.7 BTU/ft2 Hr F
Mild Steel = ?
Hard Steel = ?
Copper = 0.03
Dan
<Snip>
keep
<Snip>
forms
<Snip>
the
<Snip>
why
<Snip>
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14) From: Tom & Maria
<Snip>
I will attempt an answer at the metals choices for drums: I think the 
desirable properties are even drum heating to all areas of the drum, 
and a metal that will adequately hold/transfer heat without holding 
it so long that changes in the heat soruce have no effect. In other 
words I think roaster builders are looking for the middle ground, and 
not the metal that transfer heat the fastest, nor one that stores 
heat too long. But probably the most important aspect is that the 
metal needs to be durable and expand/contract regularly and 
predictably over time. TYou have these think steel endplates in the 
drum that aren't going to move much as the drum expands, and you're 
going to have bad drum rubbing if the drum metal expands too much. I 
know the end plates are milder steel in a Deidrich, and they need to 
receive heat from the drum by transfer, since they are not near the 
heating elements to get any direct heat. Lastly, the choices in the 
thickness of these metals is going to be a key to their thermal 
performance too. -Tom
--
                   "Great coffee comes from tiny roasters"
            Sweet Maria's Home Coffee Roasting  -  Tom & Maria
		1455 64th Street Emeryville CA 94608
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15) From: Tom & Maria
<Snip>
e
<Snip>
o
<Snip>
t
<Snip>
Thanks for the research Dan -very very interesting!
Tom
PS: I was looking at your "paint" swatches next to the SCAA Roast 
Tile kit yesterday. Those swatches are very useful! At first I was 
stunned how close they were except for  one, later I looked at them 
more critically (hey, I used to do color correction printing on these 
big expensive IRIS drum printers) and realized they weren't as close 
as they seemed at first, but for all intents and purposes they are 
very, very useful, and much less dough than the SCAA kit...
Tom
--
                   "Great coffee comes from tiny roasters"
            Sweet Maria's Home Coffee Roasting  -  Tom & Maria
		1455 64th Street Emeryville CA 94608
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16) From: Steve Wall
On Wednesday, February 12, 2003, at 10:24 AM, Dan Bollinger wrote:
<Snip>
<Snip>
I did a little web searching myself and if you think the difference
between mild and hard steel is interesting, wait until you see the
stainless steel values.  The website I came up with
showed the following:
Low Carbon Steel (W/m.K)  40 - 70
High Carbon Steel         38 - 46
Stainless Steel (316)     14 - 16
Steve Wall
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17) From: floyd burton

18) From: floyd burton

19) From: Rick Farris
<Snip>
I'm a cook, Floyd, not a welder.  :-)  You'll notice I discussed the
*cooking* aspects of cast iron, not the "properties of materials" aspects.
Mostly I have 3-ply All-Clad SS-AL-SS pans, but I do use cast-iron for a few
things.  Anything that I'm going to brown and then toss in the oven for a
while I use enamel coated cast-iron for, like gumbo or small-to-medium sized
roasts.
Whenever I want to put a really good sear on something I use a cast-iron
skillet heated almost to red-hot.
I never use anything but cast-iron for cornbread.
I probably wouldn't use anything but enamel-coated cast-iron for stews.
-- Rick
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20) From: Rick Farris
Steve wrote:
<Snip>
<Snip>
So that's almost useful, Steve.  ;-)
How about expressing it in the same units as the original post?  Or
converting the English to metric...
-- Rick
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21) From: Ben Treichel
snip
<Snip>
So again I ask my favorite question. What makes the difference between 
'drum' roasted coffee, & hot air roasted coffee?  What is the critical 
element?
<Snip>
Yeah, and which ways give the same end result?
<Snip>
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22) From: Steve Wall
On Thursday, February 13, 2003, at 02:36 AM, Rick Farris wrote:
<Snip>
I didn't think it was necessary, figuring everyone could
see the relative conductivity of plain steel and stainless
steel in one set of units and do at least a qualitative
comparison to copper and cast iron in the other.  Which is
about all that's required for mailing list engineering.
Steve=
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23) From: R.N.Kyle
Yes you can weld cast iron, using a nickel rod, and you can also braze =
cast iron. Nickel rods are expensive. 
Ron Kyle
Anderson SC
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24) From: Dan Bollinger
<Snip>
I can't get any good numbers for steel, but an educated guess is in the
0.45 - 0.55 range.  Iron is a GOOD radiation material.  Many people have
talked about how they think drum roasting is different because it heat by
radiation, not just convection. They may be right. There is a reason iron is
used for radiators!
Glad you think the swatches are useful, Tom. I plan on pasting mine to a
long strip for better comparisons. I gave up trying to match the Agtron
tiles.  Instead, I made a range of dark-to-light values.   Dan
Thanks for the research Dan -very very interesting!
Tom
PS: I was looking at your "paint" swatches next to the SCAA Roast
Tile kit yesterday. Those swatches are very useful! At first I was
stunned how close they were except for  one, later I looked at them
more critically (hey, I used to do color correction printing on these
big expensive IRIS drum printers) and realized they weren't as close
as they seemed at first, but for all intents and purposes they are
very, very useful, and much less dough than the SCAA kit...
Tom
--
                   "Great coffee comes from tiny roasters"
            Sweet Maria's Home Coffee Roasting  -  Tom & Maria
1455 64th Street Emeryville CA 94608
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25) From: Dan Bollinger
I did a little web searching myself and if you think the difference
between mild and hard steel is interesting, wait until you see the
stainless steel values.  The website I came up with
showed the following:
Low Carbon Steel (W/m.K)  40 - 70
High Carbon Steel         38 - 46
Stainless Steel (316)     14 - 16
Steve Wall
Wow.  That is an amazing difference. SS is made with a large amount of
nickel and chromium. Dan
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26) From: floyd burton

27) From: floyd burton
Ben-I don't think there is a pat answer to that question-some people report
scorched beans with some drums-maybe not enough agitation but IMHO those
thin SS drums act very differently from a heavier steel drum with few holes.
Jim S is getting good/great results from his highly modified air
roaster-apparently there are lots of roads-only time and people willing to
experiment and share their results will yield some clues.

28) From: Ben Treichel
Well the Drum King, aka Ed N, got some of my roast from a heavily 
modified FR+. Maybee he can clue us in a little bit of he is familar 
with Horse in a drum. (not janitor :-( )
floyd burton wrote:
<Snip>

29) From: Tom & Maria
<Snip>
I will hazard a guess that the Frontgate people are convective drum 
roasting, getting a lot of hot air flow through the drum, and others 
are getting heat transfer through conduction and radiance. A hot air 
flow in a drum roaster is still a long, long way off from coffee 
being suspended in a fluidized bed of hot air, and the hugely 
different rate of heat transfer between the two processes suggests: 
coffee at yellowing at 5 minutes in a Diedrich and 1-1.5 minutes in a 
Sivetz air roaster. A Diedrich is really getting a lot of its heat 
transfer through the convective air flows, along with conduction from 
the drum.
Tom
--
                   "Great coffee comes from tiny roasters"
            Sweet Maria's Home Coffee Roasting  -  Tom & Maria
		1455 64th Street Emeryville CA 94608
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30) From: Tom & Maria
<Snip>
I am not too knowledgeable about metals as some other list members 
seem to be, but I would say there are going to be a lot of benefits 
going with thicker material for drums from both a structural point of 
view and thermally. A thicker drum will take longer to heat but would 
disperse heat more evenly to all parts of the drum. Diedrich makes a 
big point of discussing their very thick steel end plates -not that 
they have any immediate contact with the burners, but that they help 
distribute heat to all parts of the drum with coffee contact. Also, 
if any of these roaster designs have contact between the open flame 
and the drum, theirs going to be some loss of metal over time, right? 
I have seen perforated with direct flame contact (not a great idea 
anyway) really degrade quickly.
Anyway, I was thinking that a contribution I could make to this 
discussion of materials is go out in the shop and measure every 
perforated roaster surface I can find, both in cooling and heating, 
in hot air and drum machines -from the chaff screen in the top of a 
HWP, to the perf in the bottom of the Zach and Dani's, to the bottom 
of the big Coffee Kinetics roast chamber, to the drum of the 
Alpenrost (I sent back my Hottop so someone else will have to get 
that... anyway, this should give an idea what the engineers out there 
have chosen for the various uses of this material. I need to place a 
McMasters order for perforated screen for our green coffee cleaning 
"scalper", and I might just get some other stock that seems useful 
for the future, too.
Tom
--
                   "Great coffee comes from tiny roasters"
            Sweet Maria's Home Coffee Roasting  -  Tom & Maria
		1455 64th Street Emeryville CA 94608
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31) From: Ed Needham
I believe there 'is' more than one way to think about drum roasting.  We've
both proven that.  Our drums are as different as night and day, and we are
both getting good roasted beans.  A thin, perforated reactive drum and a
variable source of heat is one way.  A thicker, solid wall, heat retentive
drum and a more indirect source of heat is another.  I have no idea what
characteristics each would bring out in the beans.  The stability of the
thicker, solid wall drum would be an asset AND a liability, as that same
stability does not allow precise changes in the roast profile.  The thinner,
perfed drum 'would' allow quick, accurate temp changes, but would sacrifice
thermal stability.  The 'system' could still be stable and reactive, but the
characteristics of the drum itself is what I'm talking about.
I do know that I like the light weight of the thin stainless for a removable
drum roaster, and the roasts I am getting are really up to snuff, as far as
my criteria is concerned.  I would definitely want a more substantial drum if
I were doing this for a living.
You and I need to do a coffee exchange and compare the roasts of a particular
coffee in each machine.  Email me off list if interested.
Ed Needham
To Absurdity and Beyond!http://www.homeroaster.comed
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32) From: Ben Treichel
I've been pondering what the differences could be between drum and hot 
air. It seems safe to say that the convection heating of the beans in a 
hot air roaster is going to be several times greater than that of a 
drum. In addition, something that has occurred to me is that when the 
beans touch the side of my FR roasting chamber that they are coming into 
contact with a surface a fair amount cooler that either the air and 
probably the beans. Therefore one could presume that they are going thru 
some sort of heating and cooling cycle as they roast. So even if I 
 would rum the same time temperature profile as a deidrich, I would not 
get the same results because the thermal gradients in my roasting 
environment are significant as compared to a diedrich, et al.
Now, I am presuming that a drum roaster (non perf'ed  drum ) has a very 
even temperature environment (insignificant thermal gradients), and I am 
also presuming that the outside of my roast chamber is probably no 
hotter than 275. This is a guess based upon outlet air temp at the chaff 
collector.
One other thing that dawned on me today is that my roasting chamber only 
weighs 7 oz (that's glass, bakelite, and screen) while my bean load is 4 
oz. That's not even a 2 to 1 mass ratio, with a significant portion of 
that mass not really contributing to thermal stability/loss. I.E. its 
not preventing the glass from cooling.
So when I think about the differences between an Alp or a SS screen / 
light drum roaster (BBQ) the conductive heating into the bean mass is 
not there, because the drum mass is several orders less. This finally 
leads me to speculate that a bean mass closer to a BBQ's min, will/could 
give a closer roast to a pro - roaster due to the lower bean mass / drum 
mass ratio.
Does this make sense guys, or am I just wandering around in cyberspace.
Ben
Coffee Roasting TechoMage WannaBe
Tom & Maria wrote:
<Snip>
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33) From: Ed Needham
It is my experience that when I began drum roasting that the first thing I
noticed was that the beans I had been roasting contentedly in my HWP air
roaster suddenly became much more interesting and flavorful.  I began to
notice that part of this change was an increase in the perceived body.  The
aroma of the beans was also different after sitting in the jars overnight.
The air roasted beans had a much cleaner, refined smell, while the drum
roasted beans were strong and sometimes would 'bite' my nose if I didn't let
the smell dissipate a bit before sniffing.  It was intense.  Drum roasted
beans are more intense than HWP beans in my opinion.
I've had some good blends when I mix air roasted and drum roasted beans.
Blending like that adds a balance and even more complexity to the flavor.  I
still air roast occasionally, and I am definitely not trying to say that one
method is superior to another.  I like the drum roasts I'm getting more than
those I was getting with the HWP.
Differences are...
Air is usually a faster roast.
Air uses convection to roast and agitate the beans.  Drum uses mechanical
agitation and radiant heat from the drum, as well as heat absorbed from the
heated air.  Some commercial drums use a flow of heated air that could also
be considered convection heat, which adds another roasting dimension.
Air uses a clean source of heated air and dispenses with the smoke
immediately.  Drum roasting allows the smoke to surround the beans.  Most
commercial drum roasters use an active ventilation system to remove smoke,
but it is more passive than an air roaster.
An air roaster uses air heated to a higher temperature flowing through the
bean mass to agitate and roast.  A drum roaster starts with a lower
temperature and increases the temps as the roast progresses.
I'm sure there are many more differences, but these are the ones I can think
of off the top of my head.
Ed Needham
To Absurdity and Beyond!http://www.homeroaster.comed
****************************************
**********************************************

34) From: Ed Needham
I think I have some Horse on hand.   Chuck Koby is coming over Saturday to
play around with the drum roaster and show me his Z and D roaster.  I hope
the roast from you is here by then so a comparison can be made.
Ed Needham
To Absurdity and Beyond!http://www.homeroaster.comed
****************************************
**********************************************

35) From: floyd burton
Top post here-I think the in the cup differences between types of roasters,
air vs drum and types of drums, heavy versus light might be insignificant if
essentially the same roast profiles were followed for each method. In terms
of roasting problems, I have yet to have any beans that were scorched-don't
think Ed has either-scorching maybe more a matter of drum design-not enough
agitation of the beans.  Maybe the differences get down to which method
provides the roaster with more control over the roast profile.  Certainally
a heavy drum will have slower changes in temperature than a lighter drum-but
that difference can be both an advantage or disadvantage.  Certainally takes
a long time to heat up a heavy drum if it is cold-will preheat mine in my
oven for my next roasting session.  The old Gothot's at Intelligentsia have
cast iron drums - must be for the heat stability of CI.  So IMHO it gets
back to having a roasting system that let's the roaster fully control the
roast profile.  How you get there is another matter and as with many things
in life-lots of ways to skin a cat.
From this whole series of posts today, have decided to use heavier material
for my next drum if I can figure out how to empty the drum without removing
it from the grill-Ed made some suggestions and I think I know how to do that
with my grill which happens to have a removable bottom.  The roasted beans
will flow directly into the bean cooler.  Now if I can get a TC and a bean
trier into the roast chamber, there is just the smoke to deal with.

36) From: Rick Farris
Well, perhaps if you told us which two of the six items listed you are
referring to as "plain steel," I'd agree with you.
From: Steve Wall
<Snip>
<Snip>
-- Rick
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37) From: Steve Wall
Anything other than the Stainless Steel.
On Friday, February 14, 2003, at 01:32 AM, Rick Farris wrote:
<Snip>
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38) From: Steve Wall
On second thought, make that anything listed below listed
as "steel", other than the stainless.  I don't want to be
at all unclear on this for Rick.
On Friday, February 14, 2003, at 06:38 AM, Steve Wall wrote:
<Snip>
are
<Snip>
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39) From: Dan Bollinger
<Snip>
Ben,  Good observation. In low thermal mass ratio roasters the quality of
the controller is even more important since it is what keeps the temperature
stabilized instead of the 'thermal momentum' of the machine itself. One
reason for a thermally massive roaster is the controller can be a simple
on-off switch or gas valve. The downside is that if you want to change the
roasting profile quickly you are screwed. It all depends on what you want to
accomplish.  If you want a long, even roast, I'd say go with a thermally
massive arrangement. If you want to profile roast, then go with a low ratio
unit.  Dan
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40) From: Ben Treichel
Should have been there by yesterday. Was only suppose to be 2 days in 
transit; that means wed or thursday. I guess the UPS needs another 
couple of billion to actually do what they say. Gee, wasn't Pont express 
faster?
Ben
Ed Needham wrote:
<Snip>
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41) From: Dan Bollinger
Rick, By now you've probably already ruled out SS, hard steel and copper as
not being 'plain steel.'  Mild steel is 'plain steel' because it has no (or
low) carbon content. It can't be hardened.  Dan
<Snip>
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42) From: Ed Needham
It was in the mailbox, but no one had retrieved it yet.  Will try it out
Saturday when Chuck Koby comes over.  Might roast some Horse in the drum to
do a seat of the pants comparison.
Ed Needham
To Absurdity and Beyond!http://www.homeroaster.comed
****************************************
**********************************************

43) From: Rick Farris
I'm sorry, Steve, I didn't mean to push you into a corner on this -- it
never occurred to me that you didn't know how to do the conversion either.
I thought you were assuming everyone did.
Ah well, Dan Bollinger will prolly chime in with the conversions pretty
soon.
-- Rick

44) From: Rick Farris
Well, that was my original confusion, whether or not "hard steel" was
stainless, or not.  Steve claims that it isn't.  Now you say it is.  
Any idea how to do the conversions between English and metric system?
-- Rick

45) From: Dan Bollinger
Well, since you asked...  :)    Actually, I'd tried to do this before.  I
should be simple, yet what I get are nonsense results.  Sorry to disapoint,
Dan
<Snip>
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46) From: Ben Treichel
Why don't you start here.http://www.engineersedge.com/basic_conversions.htmRick Farris wrote:
<Snip>
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47) From: floyd burton
As with many things in life there are many routes to nirvana or whatever
your goal happens to be.  Being a cheap slacker I ended up with a cold
rolled steel drum for the following reasons:
SS or AL 10" pipe could only be bought in 20' lengths-called several supply
houses in the Chi area
A fabricated AL 10" 1/4" thick pipe was very pricey
Lowe's was out of SS trash cans
Attempts to make a conical end piece from a Wally's World asian SS bowl
dulled a new titanium bit-they (the bit) cost $3
At my last stop, the steel fabricator, said stainless was a bear to work so
I ended up with cr 18 gauge steel-nasty and cheap
So there sloth, cheapness and someone used to finding the path of least
resistance to achieve a goal got me to cr steel-never knew anything about
coefficient of heat or anything else to do with and I forgot about my
concrete mixer in the basement.

48) From: Ben Treichel
Sloth is not a bad thing. I presume that you all are aware of the design 
rule that says that 85% of the effort is expended in achieving the final 
10% of perfect. Also, that means that if you send 15% of your effort 
getting pretty darn good, you have 85% of your time left to experiment 
with items that probably have a bigger payback. Like better and more 
repeatable controls, and learning what profiling does to coffee.
floyd burton wrote:
<Snip>

49) From: Bart Frazzee
I like this one!http://www.convert-me.com/en/Bart
On Sat, 15 Feb 2003 09:18:43 -0500, you wrote:
<Snip>
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50) From: jim gundlach
Or if you want the web site to calculate it for you go to:
   http://www.digitaldutch.com/unitconverter/Jim Gundlach
On Saturday, February 15, 2003, at 08:18 AM, Ben Treichel wrote:
<Snip>
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51) From: jim gundlach
Or if you want the web site to calculate it for you go to:
   http://www.digitaldutch.com/unitconverter/Jim Gundlach
On Saturday, February 15, 2003, at 08:18 AM, Ben Treichel wrote:
<Snip>
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52) From: Rick Farris
Hey, I'm a lowly computer programmer and I admit it.  Why don't *you* start
there and just give us the answer?
-- Rick

53) From: Rick Farris
Several of you have recommended websites for doing unit conversions from/to
metric and English.  Perhaps you weren't following the thread, because the
problem was to convert between:
		BTU/ft2 Hr F
and:
		W/m.K
You *don't* do it by simply converting watts to BTUs, for instance.
Something looks seriously whacked in the m.K term.  What does that mean?
Meters times degrees Kelvin?
Notice that the top form has a time component.  Where did that baby
disappear to in the bottom form?
-- Rick
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54) From: David Lewis
At 3:48 PM -0700 2/15/03, Rick Farris wrote:
<Snip>
I'm not sure just what the conversion would be, but I can answer your 
question. BTU, or British Thermal Unit, is a measure of energy, 
analogous to the Joule in the metric system. Watts, on the other hand 
refer to an amount of energy in a specific amount of time.
Best,
	David
-- 
Less than 0.1 percent of the U.S. population gave 83 percent of all 
itemized campaign contributions for the 2002 elections, according to 
the Center for Responsive Politics.
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55) From: Dan Bollinger
Rick, It's weird, isn't it?  I can help a little but not much, and like you
said earlier, the trend is obvious anyway.  1 BTU/Hr equals 0.29 Watts.  And
in the first one you will notice that it is area (ft2)  and in the second it
is distance (m).  That's because the first one was BTU/ft2 Hr F for every
inch of thickness.  So the plot thickens.  And then to make matters even
weirder, the second one, W/m.K, mixes Imperial with Metric!  Frankly, I gave
up. I had coffee to roast, company was coming!  Dan
<Snip>
from/to
<Snip>
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56) From: AlChemist John
Sometime around 16:07 2/15/2003, Dan Bollinger typed:
<Snip>
Dan, where did you get your original numbers?  From what I can tell the 
units you posted (BTU/ft2.Hr.F) should have been BTU/(ft2.hr.F/ft) for 
thermal conductivity.
Using the following:http://www.processassociates.com/process/convert/cf_tcn.htm15   W/(m.K/m) (SS 316) EQUALS   8.67  Btu/(h.ft.F/ft)
which does not seem to work.  That seems to say (based on the original 
post) that SS is twice as thermally conductive as copper (4.5).  Doubtful
Very confusing :-(
<Snip>
--
John Nanci 
AlChemist at large
Roasting and Blending by Gestalt
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57) From: Dan Bollinger
Sometime around 16:07 2/15/2003, Dan Bollinger typed:
<Snip>
Dan, where did you get your original numbers?  From what I can tell the
units you posted (BTU/ft2.Hr.F) should have been BTU/(ft2.hr.F/ft) for
thermal conductivity.
Using the following:http://www.processassociates.com/process/convert/cf_tcn.htm15   W/(m.K/m) (SS 316) EQUALS   8.67  Btu/(h.ft.F/ft)
which does not seem to work.  That seems to say (based on the original
post) that SS is twice as thermally conductive as copper (4.5).  Doubtful
Very confusing :-(  Al
Yes, very confusing. I used two sources.  One was my Machinery Handbook.  It
was in/in  The other was an online table, it was ft/ft.  I interpolated to
make the consolidated table.
Here is what the MH had in Btu/(sec - in.F/in) for heat transmission (not
radiation)
Copper = 0.00404
Steel, hard = 0.00034
Steel, soft = 0.00062
Iron = 0.00089  (note that this is not cast iron)
Dan
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58) From: Rick Farris
John, are you using periods to indicate multiplication?  (We computer
programmers normally use an asterisk.  Of course that's not the strangest
thing we do.)
-- Rick

59) From: AlChemist John
Sometime around 22:14 2/16/2003, Rick Farris typed:
<Snip>
Well this computer programmer also uses an asterisk.  I was using periods 
because the Engineers were using them and I stayed consistent. :-O  Check 
out the original posts.
--
John Nanci 
AlChemist at large
Roasting and Blending by Gestalt
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60) From: Barry Jarrett
At 11:04 PM 2/13/03 -0500, you wrote:
 >Now, I am presuming that a drum roaster (non perf'ed  drum ) has a very 
 >even temperature environment (insignificant thermal gradients), and I am 
 >also presuming that the outside of my roast chamber is probably no 
 >hotter than 275. This is a guess based upon outlet air temp at the chaff 
 >collector.
i think this would be an inaccurate presumption.  airflow within a drum is
turbulent, and comes from a variety of locations.  on my diedrich, i can
make the bean temp probe and the drum air probe read dramatically different
on an empty drum by changing some controls around.  if you're talking about
the drum itself, then yeah, i'd say it is pretty evenly heated, and pretty
damned hot.
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