Roasting advice on bk-600 (BC-2) - Page 2

Discuss roast levels and profiles for espresso, equipment for roasting coffee.

#11: Post by ymg »

Jb3 wrote:Turning off the gas and then back on at the 1:00 mark gets rid of that steep ROR. I've notice with my graphs and others here on the forum, that you can tell who does this sort of "soak" by the steep ROR at the beginning of the roast.
that's sound interesting, can u elaborate on that?



#12: Post by Jb3 »

There's a relationship between the difference in ET and BT, and the ROR. The greater the distance between the ET and BT the higher the ROR. If the ET is pretty constant as in your case, the BT is going to bungee super-fast at the beginning of the roast therefore causing the ROR to spike. If you turn off your gas for a minute or so as soon as you charge, you allow the mass of the beans (assuming you've charged at the correct size for your roaster) to weigh down the ET. You'll notice the distance between the ET and BT won't be as drastic, which in return will cause your ROR to be more flat. In your roaster, 300 grams in my opinion is too low of a charge, that's why you are getting that bungee reaction at the beginning of the roast. I hope that helps.


#13: Post by ymg »

wow many thanks, you really nailed it.
just try and the ROR speak really improved (only messed up at the end of the roast)

the initial fast ROR decline is match better now...

when i turned down the gas the machine started to beep so i put low gas pressure for the first 1.5 minute or so
when is the exact point i should put the gas up? one minute exactly or at the turning point?

i used the following setting :

air flow: 42
drum speed 60

how do i know lets say if i see ROR crash, and i trying to repair it - how do i know if to open the dumper or air flow or use the gas?


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#14: Post by keno »

As the owner of a BC-2 I have a few suggestions for you.

1. First, and most importantly, 300 grams is a pretty small batch for this roaster and smaller batches make it a lot harder to control. The roaster is really designed for about 600g batches and has the power to go up to about 800g. You will actually find it a lot easier to control with a larger batch size. You also should stick with a single batch size because changing the batch size requires changing air, charge temp, gas levels, drum speed, etc.

2. If you are going to use a smaller batch size turn the drum RPM down to around 20-25. Slower RPM will help keep the bean mass around the probe and better stabilize your temp readings.

3. Start with a lower charge temp (say 375F) and try a soak where after charge the gas is at the lowest possible setting and then wait about 30-60 seconds before turning the gas up. This will ensure you don't scorch a smaller batch and it will also help eliminate the big RoR spike you are getting along with the following drop.

3. Use a lower air flow and do not change it during the roast. With smaller batch sizes and the lower gas setting required the roaster is very sensitive to airflow changes and it can give you a roller coaster RoR.

4. Look at your Artisan settings. There are some settings that can make your curves too volatile and then you may make the mistake of overcompensating as you try to control the roaster. Generally fewer changes is better than too many tweaks.

5. Practice, practice, practice. You just got your roaster and it takes time to learn a new machine. Especially with so many variables to play with. Only change one at a time to learn what each does. Experiment and take notes. Be patient.

6. Don't get too fixated on profile curves. They vary a lot from roaster to roaster due to probe size and placement as well as airflow and thermodynamics. Focus more on objective roast milestones like time to yellow, time to first crack, and if you are roasting darker time to second crack. Taste what you roast and work on correlating taste with roast profile, don't just try to force your profile curves to fit the Rao template.

7. Finally, you definitely don't need to shut off a burner. The roaster works great. I am able to reliably do a 100g sample roast but the curve looks quite different since the probe isn't fully in the bean mass.

Hope this helps!


#15: Post by ymg »


thanks you all for your response.

what air flow setting do u recommend to use?

what about the dumper settings?

what is the recommended gas setting to turn up after i close it to the minimum?


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#16: Post by mkane »

We use a BC-1. This roast is 350g.



#17: Post by ymg »

thank u for posting your profile..

i see that you essentially playing with the gas, lowering it all the way gradually.

but i have also manual damper.

what hot setting should apply to 600 gr?
what do to with the manual dumper ?

should i play with the gas or the dumper?

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#18: Post by Moxiechef »

ymg wrote:hi

thanks for your input.

please see attached artisan graph , i marked the area that i think need to be repaired.


as you see, after the turning point the ROR is crashing way to fast.
question is, how to i extend the ROR to decline slower? i tried several methods but yet managed to archive it....

Per Rao, you've really got to ignore the first few minutes of ROR data, he says it's just false data and isn't a true representation of what the beans are doing.

Also, he suggested soak times between 1 & 2 minutes. Could see the gas on your graph.


#19: Post by ymg »

ok so this is what i got so far:

1. charge temp : 174~220c, how do i know which one is the best?
2. soak for 1 minute or so...
3. turn up the which level? (i used 0.7 at my second posted graph)
4. let the roaster develop by itself and dont force it to match
5.use constant air flow-flow, when using smaller batch size turn the drum RPM down to around 20-25, if not then 50-60
6. dumper setting during the roast?

thx all

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#20: Post by mkane »

Looking at the profile I posted above 3.0 was the damper setting. As you can see the ET didn't quite reach the 450° milestone so, the damper setting needs to come down a bit, around 1.66 give or take. Trying to keep one eye on BT and the other on ET. Were getting there but no quite there yet. I'm thinking the ET temp is critical. The profile can look good to great but if the heat milestones are not reached the roast can taste flat.