HomeRoast Digest

Topic: HG: air roast or drum roast? (24 msgs / 454 lines)
1) From:
I'm guessing the great hg with leaf blower roaster from the contest awhile back must act like an air roast (great for bringing out those high notes), but what about HG/ BM or HG/DB?  Is it more of an air roast characteristic or drum-like?

2) From: Kris McN
I think the HG/BrM ends up being somewhere in between a strictly fluid bed
and drum roast.  Now, mind you, I've never roasted with a drum, so take this
with that in mind.  I started roasting with an IR2, and brightness was kind
of a given, but you really had to work for body.  When I switched,
brightness wasn't a given anymore, but body development was easier.  I've
assumed that's at least in part because the roasts take longer, even given
the same shaped roast curve (if that makes sense).  Even my fastest roasts
now are not as fast as any roasts I ever did in the IR2. This is one of the
reasons I really like roasting with the HG/BrM - I feel like I have better
control over bringing out both these elements in a given bean.  You get the
best of both worlds, and you don't have to worry about the whole chaff
burning and affecting the flavor like in some of the drum roasters.
Kris McN
I'm guessing the great hg with leaf blower roaster from the contest awhile

3) From: Justin Marquez
HG/DB is more like a an air roast than a drum roast.  The heat is imparted
directly by the hot air of the HG, whereas in a drum roast more of it is by
contact with the drum than by circulating hot air (although that obvoiusly
is in there, too). In a HG/DB setup, if you actually had a solid bowl, then
that might be more drum-like when compared to the results of those of us who
use a wire mesh strainer to hold the beans while roasting.
Here's my guess -
Popper = Almost all hot air roast, least drum-like
HG/Mesh = Mostly hot air roast
HG/Actual Bowl = Possibly more drum-like
HG/BM = Possibly more drum-like, but probably roasts faster than HG/DB
Drum = Most drum-like (heheh)
On 11/4/07, thirddayhomeroaster 
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)

4) From: raymanowen
"Is it more of an air roast characteristic or drum-like?"
No- it's more like Fabulous- you have far more control with a heat gun if
you just use it.
Cheers, Mabuhay -RayO, aka Opa!
Got Grinder?
On Nov 4, 2007 7:58 PM,  wrote:

5) From: Vicki Smith
I can't be sure about this, but it seems to me that those of us who love 
  HG roasting are not caught up in the techie parts involving roasting 
to specific temperatures and getting repeatable on-the-money results 
from careful profiling.
To my mind, it is the intimacy of the roasting process as we use all of 
our senses to monitor and control the roast that is the big appeal for 
many HG/BM roasters.
After many, many roasts, the truth is I can nail a fairly large 
percentage of mine, but it is only because I have done so many and have 
come to understand in a pretty non-cognitive, sorta intuitive, way what 
is going on and adjust things as I go along.
I have, btw, done bean mass temp readings from time to time, and you can 
develop specific profiles for specific beans easily enough, it's just 
not how I choose to do it most of the time.
raymanowen wrote:

6) From: Justin Marquez
Carrying forth with the idea that I would put my old Wagner 1000 out at our
RV, I popped into Home Despot looking for a new one.  They had NO Wagner
HG's!  But... they DID have a Milwaukee Model 3300 for $40.  It is 1500
watts, has three fan speeds and digital temp controls for temps up to 1500
deg F. And, it doesn't feel heavy.  I know I could shop around and find the
Wagner for $25 - $30, but this new one seems like it is worth $10 more.
I bought one, and I plan to do some temp measurements of the old Wagner and
the new Milwaukee air outputs.  I will try to get some data together and
post it here sometime this weekend when I have more time to mess with it.  I
think it would be helpful to know what setting on the new one produces the
same output temp as the Wagner so I will have a starting point that is
relevant to my 2+ yrs prior roasting experiences.
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)
On Nov 8, 2007 4:39 AM, Vicki Smith  wrote:

7) From: Rich
The proper parameter is the combination of temperature and air flow. 
How may degrees at how many SCFM?
Justin Marquez wrote:

8) From: Justin Marquez
The airflow is not given in the specs for either model.  I know that the
Wagner 1000 is minimal but useable. It will blow the beans around a little
AFTER they have gone thru 1st crack.  I will try to give some quantitative
idea of air movement as best i can with no way to actually measure it. I
think I can probably tell if it is moving less air or more air. I can
measure the air temperatures, as I have a thermocouple setup to a DVM with a
Deg C temp readout setting.
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)
On Nov 8, 2007 11:39 AM, Rich  wrote:

9) From: Rich
As a point of reference the master HG-751b is rated at 750 degrees at 23 
SCFM.  I seriously doubt that any of the 20 to 40 dollar competition is 
anywhere close to that air flow.  You could build a sharp edge flow 
meter and hook a slack tube water manometer to it.  Even uncalibrated it 
would be close.
Justin Marquez wrote:

10) From: Frank Awbrey
Rich, I'm thinking that the "optimal" CFM flow was somewhere around 14 cfm?
This, if I remember correctly, is listed on the homeroaster site (Ed's
site)(going by memory here)(which really hasn't been working too good for me
lately :>)). I'm curious as I'm thinking of taking up the heat gun roasting
On 11/8/07, Rich  wrote:
"Still the one"

11) From: Rich
How did someone determine "optimal".  There are five major variables 
plus the beans in play here.  heat gun outlet air temperature and air 
flow in SCFM, the total BTU input. Distance from end of gun to bean 
surface.  Bowl shape. And the beans themselves for a total of six. 
Ambient temperature, wind velocity, moisture content and mass of beans, 
and stirring method are also considerations but are easy to normalize so 
can be discounted.
I roast a pound of greens in a 4 quart ss mixing bowl.  It is a West 
Bend brand bowl.  beans are stirred with a whisk, not a spoon.  At the 
distances that I am using I complete a roast in 14 to 15 min to FC+. 
This is done by the zen method of determining roast progress.  I might 
go for a bean mass temp probe but have not dedicated a bowl to roasting 
yet.  A dedicated bowl will allow mounting a permanent probe into the 
bowl. engineering curiosity only.
Now, the HG-751b is heavy and cumbersome at best.  To address that 
problem I clamp the gun by the part of the housing at the switch between 
two wood pads into my bench vise.  Point gun into bowl at about 40 
degree angle.  I have a 2 1/2" thick block of wood which allows raising 
the bowl  that amount.  This gives a minimum of 2 heat ranges.  the 
longer distance is used for a lower dT/dt and the shorter for a higher. 
  This results in the 15 min roast time.  If I decrease the angle and 
decrease the distance the roast time is reduced to less than 7 min.
I have several other heat guns used for other items/jobs but the Master 
is the one that seems the best for roasting coffee.
Frank Awbrey wrote:

12) From: raymanowen
"in a drum roast more of it [Heat transfer] is by contact with the drum than
by circulating hot air (although that obvoiusly is in there, too.)"
The obvious rarely accounts for the laws of geometry or physics.
From the standpoint of the spherical bean tumbling inside a flat metal
cylinder, the actual contact area is practically Nil. The hot air inside the
temperature moderating mass of the drum fully envelopes the beans at all
times. Heat transfer from the drum's surface really does not occur by
metal-to-bean conduction.
When soldering wires to terminals, it frustrates the novice when heat
doesn't transfer from the hot soldering tip to the wires or terminal. The
tip is first fluxed clean and wetted with melted solder to transfer the
heat. Until that's done, no soldering takes place.
Beans roast when they get hot, and if it is satisfactory to have the roast
progress through the accumulation of microscopic roasted surface dots,
postulate the theorem and patent the idea. [The Calculus Roaster]
A drum is mostly a container for the roasting beans. The same fluid that
heats the drum exists within the drum and has the same heating effect on the
beans. In addition to being a bean container, the mass of the drum tends to
moderate temperature excursions.
Flames and heating coils are far hotter than roasting temperatures, so the
thermal drafts from these heat sources cannot be allowed to contact the
beans directly. The lack of these high temperature thermals might be the
difference between drum roasts and everything else- the heavier the drum,
the better.
Cheers, Mabuhay -RayO, aka Opa!
Got Grinder?
On Nov 5, 2007 10:20 AM, Justin Marquez  wrote:

13) From: Vicki Smith
I use a Mastercraft Heat Gun Product #54-6500-6. It used to be that I 
could buy one as a stand alone item for $35. Now it comes only as part 
of a kit for 20 bucks more. These are the only specs I can find: Dual 
heat: high 475° C, low 250° C. 12.5A, 1500W.
The place I bought it, occasionally runs these as a door crasher special 
for $15. I have some extras :).
My first one lasted well over 100 roasts, and probably would have lasted 
longer if I hadn't dropped it several times onto the concrete garage 
floor. It came with a three year warranty and was replaced at no cost, 
no questions asked.
It is light weight. Depending on what bean I am roasting and the profile 
I am going for, I get good results with the heat gun anywhere from 2-4 
inches from the beans and using both of the heat settings. Depending on 
degree of roast and what I feel a particular bean needs, a one pound 
roast takes me between 12-16 minutes.
Would a more expensive heat gun do a better job. Mebbe, mebbe not. Would 
I buy one knowing that it too will undoubtedly get dropped onto that 
pesky concrete floor? Ummm no.

14) From: James Raven
One question Vicki,
Does your heat gun get hot enough to light a cigarette?
I own a couple that do and will but don't know the min. & max temps of them=
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15) From: Rich
Your results are compatible to min so i would not change unless you have 
a large vice to capture the  pound heat gun.  Dose not sound like you 
would gain much if anything from a change.
Vicki Smith wrote:

16) From: Rich
Spelling correction
Your results are compatible to mine so I would not change unless you 
have a large vice to capture the 4 pound heat gun.  Dose not sound like 
you would gain much if anything from a change.  I do maintain a 
consistent heat setting on the gun and only change the distance.
Rich wrote:

17) From: Vicki Smith
475 C = 875 F. I don't smoke after roasting ( or after anything else ) 
so I have never tried. Paper burns at 454 degrees F, but I don't know 
what it takes to burn tobacco.
James Raven wrote:

18) From: Vicki Smith
I like to move the gun around as I roast. My sense has been that when it 
is aimed in one place, I would risk scorching the beans as they come in 
contact with the part of the metal bread pan the heat is aimed at. This 
may not be true.
I guess, in truth, moving the HG keeps me entertained.
I tend to go from the high setting to the lower setting somewhere in the 
middle of first crack. I do that because I often want to extend the time 
between 1st and 2nd, and that helps. I also don't want the roast to get 
away from me (hasn't happened yet) and have a fire in my bread machine.
I feel that the combination of two settings and the ability to change 
the distance from the beans gives me more flexibility. YMMV.
Rich wrote:

19) From: Rich
What I like about the high air flow, 23 SCFM @750F, is that I do not 
have to move the gun to distribute the heat across the beans.  A failure 
to stir results is an almost even side to side scorch, very rapidly. It 
is hotter on axis but as the heating element is orange that is radiant 
Vicki Smith wrote:

20) From: James Raven
Vicki -
Just curious in case the need ever arises for me to use it for this specifi=
c purpose.
Thanks for your info.
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21) From: Frank Awbrey
Rich, let me apologize for saying what I said. I used the word "optimal". I
did not see it used in the article. Again I apologize. I don't want to give
out bad info.
On 11/8/07, Rich  wrote:
"Still the one"

22) From: Justin Marquez
The Wagner 1000 definitely requires moving around as you have to get close
down onto the bean mass to keep the heat going in a straight HG/DB roast.  I
can see where the high air flow and more power would let you do what you
describe. That would also allow for sitting the HG on a stand.  Sweet!
I may eventually try to quantitatively measure the air flow of the Wagner
1000 vs. the Milwaukee 3300 but not in scheduled Saturday's experiments.  We
have a short music gig on Sat morning and a great acoustic concert to attend
Sat night and a host of Honey-do's in between.  What I am hoping to learn
Saturday is:
1) What settings on the Milwaukee match the temps for "HIGH" and "LOW" on
the Wagner
2) How closely do the temp range settings match the temps they display
3) Some rough idea of how airflow compares between the two HG's
4) How long it takes to roast 1.5 Cups greens with the Milwaukee 3300 (I
already know what the Wagner will do)
As much of this as I can garner on Sat, I will report back here the results.
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)
On Nov 8, 2007 6:51 PM, Rich  wrote:

23) From: Rich
I was not offended, just surprised that there was an "optimum".  There 
is probably no real "optimal" setup for any coffee roasting.  I did 
measure the distances that I am roasting at today and the low heat ramp 
is at 5 1/2" centerline of gun to beans and the high heat ramp is 3". 
The bowl does not move except side to side under the gun and i normally 
keep the gun aimed into the center of the bowl.  I stretched the last 
batch out to 18 minutes to FC+.  Initial at low heat rate till start of 
1st crack then high heat rate till 1st was going strong and then back to 
low to finish.  Initial bean crunch was nice.  I will be into it by 
tomorrow or Sunday at the latest.  The bean in question is Ethiopia Org. 
Sidamo DP -Special Selection.
Frank Awbrey wrote:

24) From: Rich
Holding the Master 751 for 20 minuets for a roast would be a major 
ordeal.  The heat / air flow does make it very nice though.  As a data 
point I am using a Master Appliance HG-751, no letters it is serial 
number 474 and is rated at 20 amps.  It is old, more than 30 years.  The 
air flow blows all of the chaff out of the bowl without setting it on 
fire so the beans end up chaff free with no additional effort.  I would 
think a simple manometer to measure the discharge pressure would be 
informative in a relative way and easy to do.  Area of discharge opening 
and pressure X inches in front of discharge opening would provide a 
quantitative measure of flow.
Justin Marquez wrote:

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