HomeRoast Digest


Topic: Variable Fresh Roast + Roasting. (6 msgs / 143 lines)
1) From: R.N.Kyle
Great Ben, now how did you do it?
Ron Kyle
Anderson SC
rnkyle

2) From: Ben Treichel
I just got it done. I have separated my heater and fan power supplies. 
So, I have my variac for my heater control, and dc power for my fan. I 
pulled the diode bridge off of the fan and I am driving the fan with 12 
volts dc.  I also removed the timer, so that I don't have to keep 
resetting it.
First roast will be later tonight. Should be interesting since I haven't 
profiled much till now.
Ben
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3) From: Ben Treichel
Okay, I snuck in the first roast. I think I'm going to br fairly happy 
with it. Before, when I variac'ed i would turn down the fan speed with 
the heater speed. That always seemed counter-productive to me. I am able 
to hit 10 to 15 degrees per minute increase, and cool down was 450 to 
275 in one minute, and 275 to 175 in the second minute. I then dump my 
beans in a little flour shifter, and just hold the hose of my little vac 
under the screen. In another 30 seconds or so, I'm at room temperature.
Ben Treichel wrote:
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4) From: Ben Treichel
There are 3 wires running into the heater fan assembly. On the ones that 
I've seen, the black wire goes to the diode bridge at the bottom of the 
fan. The Red and white (non-fan wires) are the heater wires. Attach the 
power plug directly to those two wires, and plug that into the variac. 
Clip the lead from the power plug to the fan, & unsolder the diode 
bridge. Get yourself an ac to dc convertor, and cut the plug end off. 
I'm using a 12 volt, 1.25 amp one. Seems to do the job. Solder that 
directly onto the fan motor. Don't know if i'm way oversized or real 
close, but it doesn't get hot. Put the unit back together, & roast.
FYI, I thought I would get fancy and use one of those multi voltage 
ones, doesn't work. They just blow up. Also, I wouldn't mind having more 
than 12 volts to the motor, but when it runs un-mod'ed, its at 11 volts. 
So I dont want to push the motor too hard right now. I figure with more 
airflow I can go from 3 oz to 4 oz, but that could take a lot more power 
(read voltage). Rule of thumb is that it takes 4 times the power input 
to double fan output.
Got questions, ask. In the mean time I'm still trying to get my grind 
and tamp reliable. Of to try yet again.
Ben
R.N.Kyle wrote:
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5) From: R.N.Kyle
Thanks for the information Ben. I planned to do this to my FR, but have =
not as of yet. Then information you have provided will save me a lot of =
time. Thanks again
Ron Kyle
Anderson SC
rnkyle

6) From: Ben Treichel
Update,
It appears that it is necessary to solder the thermal switch shut in 
order to properly profile. I had achieved 350 in 5 minutes, and then the 
thermal switch kicked in on the second roast and messed things up. Time 
to open her up again and do the mod.
Ben
Ben Treichel wrote:
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