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· 02/11/2020 1:10 PM
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· 02/11/2020 9:35 AM
The Behmor lol

· 02/10/2020 10:25 AM
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· 02/06/2020 7:24 AM
Searched but no can find, but does anyone on here use the roasters made by CRC (Coffee Roasters Club) in Connecticut?

· 02/05/2020 2:50 PM
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The well tempered roaster


8675309 wrote:

I drilled a hole in my Chaff collector on my SR500 and use a probe to measure temp with very interesting results and a much better quality roast time and time again.

I monitor the temp and adjust settings accordingly and was quite surprised that the 'low' heat setting on the SR500 moved into the 400 range basically to FC and beyond and then I'd set to 'med' heat setting to prevent stalling finding 2C occurring around the 500 mark.

I get good consistent roasts now and love it.

Did you have insight into temp before? If not I would imagine any temp measurement would help
Is important to have a good reading of real ET maximum, to avoid the 270-280 C limit, where the cellulose matrix of beans is destroyed. Grin
interesting simplicity, I wonder how it would translate to my fluid bed machine... In theory temp is temp, But I know its not that simple...

I usually manually "chase" the desired curve holding the ET 40 or so degrees above my next mins target temperature... Would be a whole lot simpler to set 400* and sit back and enjoy the aromas. This would roast my beans a whole lot faster since it starts out so high.

I'll give it a whirl next roast in a week or so and see how it does
Indeed, not so simple...
You need at least two steps, because beans don't like to be thrown directly into an environment hotter than 200 C.
So, try to reproduce what wise men wrote in the first post.
Okay, I also think this is an intriguing concept, the idea of controlling the roast by ET which becomes the independent variable, and allowing the BT to be the dependent variable.
If you hold the independent variable constant, then the character of the bean basically defines the roast.
The terminology is unfamiliar to me, especially “start temperature.” I am going to assume that this is the charge temperature.

So, the problem with all of this is that my Hottop *never* gets to 450F. I am roasting only 150 grams of beans, and I start the roast at 350, then charge. The ET drops down to like 285 and then slowly creeps up. By the time it gets to 405, my beans are at first crack. I gather from this that with any beans at all in my Hottop, it simply can’t get to 450 ET.
So, either we Hottop guys are extremely lucky that we never have to worry about the ET going beyond the safety point, or, we Hottop guys are so unlucky that our roaster simply cannot get hot enough to do a decent roast, so all our efforts are producing crap.
Or, perhaps there is something funny about that 450F number? Perhaps the Thermocouple needs calibrating? But it’s funny, the BT thermocouple seems to be pretty much dead on as far as first crack temp.
I have heard of some techy geeks out there plugging into a variac and upping the voltage on their Hottop element to get more heat out of it. I don’t think that is what the manufacturer intended. Can you say, “how do I dramatically shorten the life of my heating element?”
So, what are we to do?
Is it just possible that the Hottop style of drum roaster is different from a hot air heated roaster? Maybe the radiant heat has an affect on the beans that doesn’t show up as temperature? Or the combination of radiant heat and conductive heat transfer from the drum makes the 450F number just wrong for the Hottop?
Just FYI, I have done a number of roasts, and passed out the results to some of my more (and less) discriminating friends. I have converted several die-hard French roast users to my City+ roasts—they told me they had no idea coffee could taste that good.
My Hottop gets to first crack just about as fast as most of the other roasters I am reading about here, although folks are notorious about not being consistent with their terminology. I think if the roaster can get the beans to first crack at the 6 minute mark and can get a good rolling crack, it is unlikely that there is something wrong with the roaster, even if it’s thermocouple never reads 450F.

So, in future, if I try this again, I am going to substitute 300 for 350, and 400 for 450. It looks to me like the 450 is just wrong for my roaster.
Edited by Tavake12 on 02/12/2020 7:47 PM
The last paragraph in JS quote sounds as a disclaimer covering cases as yours Grin


This ET part is basic roasting chemistry, and the same for all roasters and coffees. But the heat inputs required moment by moment to achieve this ET curve is based on the roaster's thermal characteristics, and is different for every roaster design.

Maybe your ET probe measure hot air in a niche where air circulation lacks and heat losses led to the behaviour you described.
Basically the ET from theory means the temperature of air where beans are immersed, so as close to beans but without contact to them.
Since this thread start I studied a lot and you can be confident, the opening quote is right, is the hot air that do the roast and nothing else. Contact and radiant transfer are simply BS, unless you have a truly FIR radiant element in the setup.
And yes, I have a lot of roasts monitoring ET only, for machines I built myself, because BT simply can't be measured for those setups.
More than this, for a Gene, using a reverse logic, computed a virtual BT based on intake hot air temperature, and got FC exactly in the ballpark of 200 C for this virtual BT reading. So really things works as in theory...
You can read a bit of additional physics on this subject (reverse computation of BT) here:
Edited by renatoa on 02/13/2020 1:43 AM
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