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Unavoidable Scorching with Hottop KN-8828-B2
Vbrock9089
Hey all! I recently purchased a used Hottop. I have roasted a Nicaraguan on it more than 20 times and cannot seem to avoid, what appears to be, scorching and an uneven roast. I have fiddled with nearly every variable that I can think of, with no success. I have charged anywhere between 220* and 380*. I have kept the fan at full blast throughout the entire roast and tried no fan. I have shut the heating element off for the first 30 - 60 seconds of the roast. I have tried a charge weight of 175g and 225g. I have both lengthened and shortened the roast, between a range of 9:00 and 16:00 minutes. I even took the whole machine apart, gave it a DEEP clean, and checked to make sure the heating element wasn't too close to the drum. Most recently, I removed the back filter 1/4 to fiddle with the air-flow. Every single roast, regardless of these alterations, has dropped like what you see in the picture. It doesn't drink well, either... Thoughts?

Coffee: https://www.sweetmarias.com/nicaragua-b ... -6127.html
Vbrock9089 attached the following image:
unnamed_2.jpg
 
renatoa
What about rotating speed, does it looks right ?
 
Vbrock9089

Quote

renatoa wrote:

What about rotating speed, does it looks right ?


I resolved the problem, and it wasn't the rotating speed, but I did notice a slight issue. At a single spot in it's rotation, the drum hesitates a little bit. It occasionally sounds like metal scratching metal when it gets to the lag point. Gonna investigate once the roaster cools down.

I got my hands on a thermocouple today. This allowed me to roast with an accurate temerature gauge. Who knew that the ET probe in an old hottop could be so far off. Turns out that I wasn't controlling 1st well, at all. My guess is that I was getting to first around 390* and getting up to 420 in 1:45 (my typical development time).
 
renatoa
Actually, absolute temperatures are not a must, the differential is what matters.
380/410 or 400/430 would be equally useful to me, if consistent from roast to roast.
 
snwcmpr
The HT uses a different logic to the temp. Something like a temp somewhere between BT and ET.
I put a probe in mine. I no longer have the HT.
--------------
Backwoods Roaster
"I wish I could taste as well as I wish I could roast."

As Abraham Lincoln said "Do not trust everything you read on the internet".
 
Tavake12
vbrock9089: You said you resolved the problem, but you didn't say how. Was the cause of your problem the fact that the drum was hanging up--or was it something else?
 
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