HomeRoast Digest


Topic: Two variacs on a Poppery I, second attempt (10 msgs / 251 lines)
1) From: Jim Anable
I weighed out 1/2 lb. of Sweet Marias Espresso Monkey Blend.  In order 
to keep the beans off the bottom of the roaster and dancing when green, 
I had to run the fan at the top of my variac level (144V) for the first 
couple of minutes.  I guessed at 85V for beginning heater voltage, and 
that seems too low.  It took too long, even ramping up 5V per minute, to 
hit first crack.  Since the fan is running over speed, I'll probably 
start out at 90V the next time.  
Stating the obvious:  Temperature is a factor of heater voltage and air 
flow.  Air flow is a factor of bean load.  By weighing exactly 1/2 pound 
each time, I'll eventually dial in the required heater voltage and how 
rapidly to ramp it up.
As soon as the beans went yellow, then chaff was blowing off, I was able 
to reduce the fan voltage.  When fan voltage is reduced, I don't ramp up 
heater voltage because that'd be two variables causing hotter operation 
at the same time.  I was under 115V on the fan between first and second 
crack (line voltage is about 122, so this is a voltage reduction).  
Beans still dancing, but not blowing out of the soup can.  At line 
voltage, I would be blowing beans out of the top with the 1/2 pound load.
The hottest I went on the heater was 110V (other than a few seconds at 
115, which seemed too hot).  As the fan voltage got reduced between 
cracks, I actually reduced heater voltage until it fell to 105 VAC.  The 
difference between 110 and 105 V may seem to be under 5%, but it's not.  
Power (wattage) is voltage SQUARED divided by resistance.  So that extra 
5V is giving closer to a 10% boost in power.  
My first attempt was too dark of a roast, because I was watching for 
smoke.  This time I kept a better eye on the beans.  I never saw or 
smelled smoke.

2) From: miKe mcKoffee
Sounds like you're getting the hang of it. Also sounds like you haven't
gotten a thermometer to measure bean mass temp yet. Believe you'll find it
much easier to track and replicate or tweak a profile if you know your times
versus temps. Definitely work with a single consistent batch weight until
you get a firm grip on how varying fan and heater voltage effects ramp.
Later you'll be able to easily roast as little as 1 bean or max batch same
profile! Also, ambient temp will be another variable for actual v to heater.
You'll also find different beans same batch weight will require different
fan voltage for same bean movement. FWIW from cold (or rather pre-heated and
fan cooled to simulate previous batch) roaster I hit voltage moderately hard
~125v (depending on ambient) until bean mass comes up to 150f (target 25
seconds) than chop heater v to ~95f targeting hitting 200f 1 minute mark.
Then gradually increase heater v for 250f 2min, 275f 3min, 300f 4min. (This
"equalization drying warming stage I vary somewhat for different beans but
never faster to 300f than 3min or longer than 4:30). In addition to
alleviating any grassiness tendancies do to too fast early this sets up good
ramp control going into beginning of actual roast-tanning/browning/1st crack
etc. stages. Obviously don't go by my specific voltages but rather think
technique and apply to how yours behaves.
Pacific Northwest Gathering Vhttp://home.comcast.net/~mckona/PNWGV.htmKona Konnaisseur 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>

3) From: Brian Kamnetz
I once tried roasting at the kitchen sink with heatgun/dog bowl. I had the
window open right across the counter, though no active way to entice any
smoke produced out the window. During roasting I didn't notice any smoke -
until I turned around and looked through the kitchen into the living room!
The smoke alarm didn't go off, but it was plenty hazy!
Brian
On 6/9/07, Jim Anable  wrote:
<Snip>

4) From: Jim Anable
miKe mcKoffee wrote:
<Snip>
Forgot to mention that...  I used a digital thermometer, the type you 
leave in the food and run the wire out the door (only because I already 
have it).  It does go to "max" at some point around 385 or so.
<Snip>
I will try that next time.  That's my problem--long time between cold 
and warm.
<Snip>
This is the type of advice I'm looking for!  What range is the terminal 
temperature?

5) From: Jim Anable
Brian Kamnetz wrote:
<Snip>
A high power range exhaust fan is in my future, for regular cooking 
needs.  I'm "collecting" stuff for a kitchen remodel (easy way of saying 
I've gotten most of the stuff, but haven't done any work).  I still 
don't know if it'll be enough, though.

6) From: miKe mcKoffee
<Snip>
Well, you got it covered UNTIL approaching 1st crack! 
<Snip>
Hmmm, I consider "terminal" temp much beyond 460f FC++/Light Vienna! (My
measured bean mass roast temps happen to closely coincide with Tom's 'roast
pictorial':http://home.comcast.net/~mckona/PNWGV.htmKona Konnaisseur miKe mcKoffee">http://www.sweetmarias.com/roasting-VisualGuideV2.htmlPacific Northwest Gathering Vhttp://home.comcast.net/~mckona/PNWGV.htmKona Konnaisseur 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/

7) From: Michael Dhabolt
Jim,
Sounds like  you're learning and having fun.
miKe's temp and ramp times closely approximates my base profile also.
Something that might help when using a P1 (if you aren't already doing
it) is to put a 5/8" to 3/4" block under the two rear feet (tilts the
popper forward).  the tilt will allow you to keep good bean
circulation going at a lower fan speed/voltage.
I use line voltage, 124 volts locally, to the heater between ambient
and 200 F - start dropping off after that. I don't need full line
voltage again until the stretch between 350 F and 385F and again drop
the voltage (on / off time for me - PID) to a slower heat up rate by
the time I hit 1st at approx. 405F.
When I was using dual variacs I controlled bean temp by manipulating
fan speed as much as possible.  slower fan = faster heat up rate,
faster fan = slower heat up rate.  Pretty much using heater voltage
changes for gross temp control and fan speed for fine temp control.
Mike (just plain)

8) From: miKe mcKoffee
<Snip>
Interesting. I use heater as primarily temp control, but do adjust fan speed
down as beans loose weight to maintain my desired slow bean movement. And
interesting because IIRC we've roasted the same coffees with very similar
results in the cup. 
Didn't roast any Brazil Yellow Bourbon today for PNWG since you were, but
maybe I should to again compare heat control methods! Shoot your profile and
I'll try to find time to roast a batch tomorrow.
Pacific Northwest Gathering Vhttp://home.comcast.net/~mckona/PNWGV.htmKona Konnaisseur 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/

9) From: Michael Dhabolt
miKe,
We've done this before - couldn't tell the diff.  With PID heat
control I currently don't manipulate the fan nearly as much as
previously with dual variacs.
Better to spend your time on the things that matter, you guys bust
your butt's to get this thing rolling (appreciated by all) and I'd
rather see you relax a little.
Mike (just plain)

10) From: Scott Marquardt
Soup can?
For large quantities of beans (up to 10 oz.), you're better off with
large pyrex tubes. Nothing quite like 'em. Search ebay for:
bread corning tube
to see examples -- but don't bid on any. They're all wrong.
More rare on ebay -- but still frequently enough offered that you'll
definitely get a pair before long -- is the "duo" set. The duo is the
only tube that's an even 3" -- which is what you need.
Mounting these to your popper requires a bit of creativity, but once
you're content with how you've arranged that, this tube is the best
thing to add to a popper after splitting and Variacing.
As someone once pointed out, removing the Bakelite topper on the roast
chamber might be necessary to make the glass fit. That's what I've
done with my Pumper.
It's a lot easier to roast 9 oz. when the beans have plenty of
headroom above them, still!
HTH
On 6/10/07, Michael Dhabolt  wrote:
<Snip>


HomeRoast Digest