[Homeroast] RK drum learning curve troubles

Charlie Herlihy zapcafe at yahoo.com
Tue Feb 3 21:59:31 CST 2015


I feel for you John. You have a lot of practice ahead before you figure it out. Some advice--first, 5 rpm will never work. 50 rpm much better, mine runs at 60 rpm.Second-never open the grill lid and take samples, that's totally out of the question, unfortunately. You can't let the grill temp drop so much during a roast. Screws up everything, irrevocably. For a two lb. batch that 525 degree grill temp sounds right except that it took 25 minutes to first crack so something's wrong there. Try for an 11 minute burn to first, or even a bit less for smaller loads, but only after you get a better motor for much faster drum spin. Start hot.  Putting in the drum will drop the grill temp more than the thermometer will show for a couple of minutes. For my 4 lb. batches I pre heat the grill to 700, but that drops down to about 600 on the thermometer within 3 or 4  minutes before slowly starting to climb back, and then I ease off the gas for a controlled rise to first. That first batch may well have been very close to 3d crack (lots and lots of flame and smoke). be careful!

      From: John Nordling <john.nordling at gmail.com>
 To: Homeroast Coffee <homeroast at lists.sweetmariascoffee.com> 
 Sent: Tuesday, February 3, 2015 7:36 PM
 Subject: [Homeroast] RK drum learning curve troubles
   
I did my first couple roasts tonight on my new RK drum roaster build  - 2
lbs each in a 4 lb drum.

In the first, they came out black (blackest beans I've ever seen), hitting
first crack at over 25 Minutes. I was going for second, but pulled them at
30. I think that was a good move - I must have been seconds from ignition.
The grill temp was held around 525 the whole time (preheated, then brought
back up as quickly as possible after loading, and monitored/tweaked
throughout the entire roast).  I was roasting blind, because I didn't want
to drop temp. (Also, I have always roasted by smell/sound on my Whirley.) I
bought a thermometer from RK, and it seems accurate, though I haven't done
a boiling water check.

The second roast took close to 15-20 minutes to hit 1st crack, which never
really took off. (I wrote down the exact time, but my log is in the
garage). I dumped it on the cooling fan at 25 minutes. I started this one
trying to maintain 550, but after 10-12 minutes, I bumped up to 575 because
I figured I was under heating. I also suffered heat loss in this
batch because I pulled bean samples at a couple points, trying to
understand what was happening. Since it was about 20 out, that caused
significant cooling. Finally, toward the end, my propane tank was getting
too cold (I think-or its almost empty, though I haven't run for that long
on it yet), so I was having trouble keeping my temp above 550 (when
starting, I was hitting 600 at 1/4 gas.  This was at wide open). That may
have also been a factor.

Also weird-very little to no smoke during the roast (except at the very end
of the first batch, but that was coffee oils considering ignition.)

Any suggestions?  I suspect I'm not giving it enough btu's in the early
part of the roast, but I wanted to bounce this off you all before I blow
through another two lbs of my sacrificial beans. (I get three more tries
before I have to either try on my good stuff, or buy more cheapos).

Finally, my surplus store motor is geared down to between 4 and 5 rpm. I
think that's ok for now, but some day I'll be ordering a faster one.

Thanks for any advice you can give.

John



-- 
~~
"Can't believe how strange it is to be anything at all."  Neutral Milk
Hotel, *In the Aeroplane Over the Sea*

Email:  john.nordling at gmail.com
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