HomeRoast Digest


Topic: DIY 1lb fluid bed roaster (16 msgs / 427 lines)
1) From: John Moody
I want to build a ス - 1lb fluid bed roaster.  For capacity, 1/2lb green
would be just fine, but I want enough power to complete a roast in 6
minutes.
I plan to use 240V electric heaters for the project rather than gas.  I知
leaning towards a cone shaped chamber design.
I知 looking for suggestions for blowers and heater elements.
Dan Bollinger痴 sample roaster seems like it might have the type of heater
that would work for me.
For a blower, I知 wondering if the blower pulled from a low priced shop
vacuum on a speed control could do the trick?
John

2) From: Vicki Smith
Any particular reason you are aiming for 6 minutes? I did 2 pounds in my 
bread machine/heat gun roaster this weekend (silly me) and was happy as 
a clam with 16 minutes to FC-FC+ time. I know I want plenty of time to 
dry out the beans before bringing them to 1st crack, then I want some 
time between 1st and 2nd. Six minutes just wouldn't cut it as a total 
roast time, given those issues.
I have, btw, completed a roast in a little more than 6 minutes--3/4 
pound of the most awful shtuff. I didn't know what a  fire in the bread 
machine looked like until then. No flames, but...
vicki
John Moody wrote:
<Snip>

3) From: John Moody
I'm looking to achieve faster roasts with lower temperature air, with the
hope of leaving more oils/aromatics in the bean.
I said 6 minutes in an attempt to keep it simple; the roasts will likely be
somewhat longer than that.  I'm really looking for a ramp capacity around
90F per minute at max air temp of ~530F.  I will use a controller for
profiling.
My HG/BM experience so far has resulted in faster roasts at high (1100F) HG
air temp, or long roasts at 500F.
John

4) From: Vicki Smith
I'm starting on the high setting, and then as 1st gets going, switching 
to low, and/or, playing with the distance between the beans and the 
business end of the heat gun. Generally I roast about a pound, and most 
roasts (I don't go very dark) finish in 12 or so minutes. Now, most of 
my more recent roasts have been with very cold ambient temperatures. In 
fact, the roasts I've done the last week or so are the only ones in 
temps above freezing in about five months. Life in Central Alberta 
doesn't stop just because it's cold, yanno.
v
John Moody wrote:
<Snip>

5) From: Ken Mary
<Snip>
Sorry, I do not mean to discourage you, but why not a drum roaster?
--

6) From: Dan Bollinger
John,  No reason it couldn't work.
You will need more heat (watts or BTUs) than my heater since you need to 
continually heat cold air you are pumping in.  I would first consider buying a 
replacement heater assembly for an industrial heat gun and mount that assembly 
in a steel tube between blower and roasting chamber. Search Grainger for 'heat 
gun element' at: www.grainger.com
Vacuum motors, as they are called, that are in a shop vac are the universal 
type. They are easily controlled with a speed controller for, say, a router 
(they both draw about the same amps).
The pressure you need is determined by the height of you green bean bed in the 
roasting chamber, not the weight of the beans.
Check out the thread on 5-20 pound hot air roasters at: http://www.homeroasters.org/php/forum/viewthread.php?forum_id2&thread_id19Dan
<Snip>

7) From: John Moody
Don't be sorry, I spent lots of time thinking about going with an RK drum,
and still like the idea.
The main reason is I actually enjoy the technical aspect of a bean-mass-temp
PID controlled roaster.  Initial tests with a PID'd HG/BM are encouraging.
I see a fluid bed as pretty easy to build if you have the heater power and
control available.
Dan's sample roaster with an IR bean temperature readout sounds really good
to me as well.
John

8) From: Ed Needham
Just for the record, static pressure measurements relate to how much push 
the air has coming from the blower.  Some blowers 'leak' around the fan and 
are slower RPM.  They don't produce enough air energy to loft the beans. 
Some generate energy with high RPM's and can sustain a higher pressure level 
just by the sheer speed of the air.  Others generate pressure by using a 
blower designed not to leak air around the fan blades.  At slower RPMs, they 
still produce higher pressure.  Some use two sets of fan blades to keep the 
pressure higher.
The biggest problem with vac motor/blowers is the high (and irritating) 
noise level.  They achieve pressure by sheer motor speed, rather than by 
using quality blowers with high static pressure levels.  They also blow a 
high volume of air at high speed.  Heating that air takes more energy, 
especially if you don't recycle it.
So choose the blower you use wisely.  I would find the blower first that 
would loft the amount of beans you want to use, and then adapt the other 
design parameters around that.  There's no easy formula for that.  At 
tinkerer level, it is pretty much trial and error.
*********************
Ed Needhamョ
"to absurdity and beyond!"http://www.homeroaster.com(include [FRIEND] in subject line to get through my SPAM filters)
*********************

9) From: John Moody
Dan,
Thanks.  I had seen that thread earlier, and it looked so _big_.  Re-reading
it, I now pick up much more information that applies to my ~3/4lb goal.
John

10) From: John Moody
Ed,
Good point.  I will concentrate on blower and chamber first by trial and
error.
I don't want it to be noisy, so that has me thinking about your multi-stage
comments.  I have a 3-stage HVLP blower that I could let perform double
duty.  With it slowed down to an appropriate level for spouting beans it
might be pretty quiet.  Full speed it puts out 101 cfm, and has 137 inH20
pressure at shutoff but is extremely noisy.
John

11) From: miKe mcKoffee
If limiting your batch size to 1/2# or slightly larger greens batch I =
"can"
(but don't) do French in 5 with split wired dual variable boost voltage
control Caffe' Rosto, fairly certain same for Mike's (just plain) Ubber
Popper P1s.
Pacific Northwest Gathering Vhttp://home.comcast.net/~mckona/PNWGV.htmKona Kurmudgeon miKe mcKoffee
URL to Rosto mods, FrankenFormer, some recipes etc:http://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately 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>

12) From: Alchemist John
And where as Ed mentioned there are no hard and fast calculations, 
there are some calculations available.  At one point I put together a 
fluid bed spreadsheet (I think it might be available by Ed's 
Homeroaster.com site.).  One of the numbers that fell out of the 
calculations is that cfm for this application is quite low.  20-30 
cfm, but the head pressure was the vital key.  Sounds like what you 
have there will work nicely, except for the noise.
At 09:00 4/16/2007, you wrote:
<Snip>
John Nanci
AlChemist at large
Zen Roasting , Blending & Espresso pulling by Gestalthttp://www.chocolatealchemy.com/

13) From: Dan Bollinger
John,  my tests (see the Excel spreadsheet at the homeroasters.org download 
area) show that you only need about 2-3 inWS to spout a 3.5" high bed.  I fear 
that by the time you get your pressure low enough on that HVLP blower you'll be 
harming the motor. A single-stage blower is sufficient if it turns fast enough.
While some of the noise comes from the fast moving blade, most seems to come 
from the universal motor used on vacuum motors. Switching that motor for an 
induction motor will be a step in the right direction.
Dan
<Snip>

14) From: Justin Marquez
To get the longer roasts on high setting : Set your HG on high, pull the
nozzle a bit farther back, stir continuously and rotate the HG nozzle in
circles over the greens.
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)
On 4/16/07, John Moody  wrote:
<Snip>

15) From: John Moody
My last statement about time and HG temp did not convey very well what I was
trying to say.
What I meant was, to achieve the shorter roast I desire, I have to set the
HG temp way above what I consider acceptable.
This is in a BM (bread machine), I have no trouble when using a dog bowl.  I
知 trying to eliminate the manual operation and breathing all the junk that
comes along with it.  The BM I知 using does not have enough agitation, and
has too much heat loss.
John

16) From: Dan Bollinger
John,  One way of dealing with the noise is to put the shop vac in another room 
or inside/outside and run its vac hose through a window. About half the noise 
comes from its intake. Dan


HomeRoast Digest