HomeRoast Digest


Topic: Adding a Timer to Modified WB I (17 msgs / 445 lines)
1) From: Andy Conn
I currently have a WBI I have modified with a 2000Watt dimmer.  I have also
added a thermometer in the side and adjusted the internal thermostat.
What I would like to do now is add a timer to the heating element/dimmer
(the fan is on a different circuit than the dimmer) so that once I profile a
roast, I can do subsequent roasts by the timer.  Once the timer reaches zero
it should break the circuit to the heater, but allow the fan to continue to
run for a automated cooling cycle.
Anybody try this or have the slightest clue where I can find a timer that
could used this way?
Thanks - Andy
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2) From: Dick Heggs
Andy: Are you always going to roast at the same ambient temperature?  Is
the humidity always the same?
Will the beans always be the same moisture content?  Will the hundreds
of other factors in roasting coffee remain the same?   I suspect you
will find you have to supervise your roast in the last stages
carefully.  Any professional roasters I have seen are constantly
monitoring the roast second by second.  I can't see the use for a timer,
but if you go ahead, keep us informed.
Dick Heggs
From: "Andy Conn" 
I currently have a WBI I have modified with a 2000Watt dimmer.  I have
also
added a thermometer in the side and adjusted the internal thermostat.
What I would like to do now is add a timer to the heating element/dimmer
(the fan is on a different circuit than the dimmer) so that once I
profile a
roast, I can do subsequent roasts by the timer.  Once the timer reaches
zero
it should break the circuit to the heater, but allow the fan to continue
to
run for a automated cooling cycle.
Anybody try this or have the slightest clue where I can find a timer
that
could used this way?
Thanks - Andy
--
R.S. (Dick) Heggs
From the Okanagan Valley of Beautiful British Columbia
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3) From: Andy Conn
I understand your concerns about the myriad other variables involved that
can alter roast time.  What I aim to do is this: if I am going to roast
several batches at time, I can profile the first (after pre-heating the WBI
of course), and then use those results to set a timer for subsequent roasts.
I think that's a fairly safe way to approach it.
The reality of my life is that I have 6 kids and things are too busy for me
to be hanging over my roaster for an hour a pop.  I could handle 10 -minutes
to profile the first batch, then, a timer for the rest would be awsome.
- Andy

4) From: John - wandering Texas
Dick & Andy;
	There are some on the list who are roasting with a laptop controlling the
whole program.  If you use a thermal couple into an AD converter, and a
couple of triacs it can be done- maybe not easily - but it has been done.
John - who's glad he's not still an IT

5) From: Andy Conn
I'm thinking more along the lines of a simple appliance timer.  I've seen a
couple on the internet that might be reasonable.  I'll check home depot
tonight.
- A

6) From: Andrew Thomas
Andy Conn wrote:
"I currently have a WBI I have modified with a 2000Watt dimmer.  I have also
added a thermometer in the side and adjusted the internal thermostat.
"What I would like to do now is add a timer to the heating element/dimmer
(the fan is on a different circuit than the dimmer) so that once I profile 
a
roast, I can do subsequent roasts by the timer.  Once the timer reaches 
zero
it should break the circuit to the heater, but allow the fan to continue 
to
run for a automated cooling cycle.
"Anybody try this or have the slightest clue where I can find a timer that
could used this way?
"Thanks - Andy"
Have you tried using your WBI, with the heater switched off, for cooling? I have one with a switch added to the heater circuit. I use the heater switch to extend the roast time, but I find this machine retains heat too long after the heater element is turned off to use it as a cooling cycle. I get much better results just dumping the beans and cooling them in a pan. Maybe you have a way of making it work as a cooler? I'd be interested to learn.
Sorry, I have no advice about a timer, but I'm looking forward to your progress report.
another Andy
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A service of www.WallaWallaGuide.com
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7) From: Andy Conn
I suppose that through trial and error (i.e. what tasts good) I've just
factored in any additional roasting that occurs in the WBI during the
cooling (when I switch off the heating element).
I'm actually pretty impressed with how fast the beans cool in the WBI.
Within 30 seconds I'd say the temp drops from 460 to around 200.
- A

8) From: Steve D - Kc4rkf

9) From: Robert Cantor
I got mine at a home depot - it's for a hot tub
Bob C.
rcantor

10) From: Steve D - Kc4rkf

11) From: Andy Conn
Steve - I stand corrected.  I did an exact measurement just now.  After
turning the heat off and leaving the fan running, it took at least 30 sec to
go from 460 to 300, and at least another minute to get to 200.
Thanks for calling me on that!
What you think - tastes better with a quicker cool down?
- A

12) From: Andy Conn
For those following the thread ...
I bought an Intermatic Spring Wound 15 Minute timer for about $19 today.
My next challenge, I want to rig up an airflow device with timer, so that as
the timer dial goes round, it moves an air-flow damper.  I believe this
could be used to automate a desired temperature curve.
The quest (unattended roasting) is on!
- A
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13) From: Ken Mary
They are a dollar at your favorite "dollar" store, but the quality may not
be as high. Great minds think alike, I was playing around with this idea
this past weekend. Mount the timer on the roaster with a bracket so that as
the knob turns, it will wrap up a piece of string and pull the damper lever.
You could even attach an off-center pulley (or use a stiff wire link) to
either slow down or speed up the rate of damper closing. This approach
should give a smooth mechanically reproducible profile for air volume
control only. But starting the timer as a preset temp is reached should fix
that. Also, rather than directly operate a damper, the timer could just as
easily turn the knob on a dimmer and control the heater as well. The
"mechanical approach" is often much simpler and better than electronic
methods. There is no feedback so if the temperature rises faster than
planned (or not fast enough) you are out of luck or must settle for a
"different" profile. An electric clock movement may be better than a spring
timer that must be set by turning the knob. Sorry if any of this has been
mentioned before as I did not bother to read previous posts.
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14) From: Angelo
 
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I think all these improvements take us further away from the idea of 
DIY...Might as well have the local roaster do it for us...
But, then again, waddaiknow?
Ciao,
Angelo
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15) From: Ted Cary
Where do you find the 2000 watt dimmer?  Ted Cary
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16) From: Andy Conn
ebay - $25

17) From: John - wandering Texas
Ya know Angelo, I think you've nailed it.  I refuse to use an automatic
keyer on my amateur radio for contesting - always saying "I don't want the
computer having more fun than I do" and here I am laying out a computerized
profile. If you could see me, you would know I look ashamed :O)


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