[Homeroast] RK drum learning curve troubles

Andy Thomas adt0611 at yahoo.com
Wed Feb 4 11:41:46 CST 2015


"motor is geared down to between 4 and 5 rpm"
John, I think this is your problem; your motor is way too slow. I am not a drum roaster, but it is my understanding that it must rotate in the 40-60 rpm range to avoid scorching the coffee. For example, the motor recommended on the RK site <http://www.rkdrums.com/index.php/en/products/misc/rk-commercialhome-motor> rotates at 52 rpm.

      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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