Kaffelogic community

To start, I'm quite new to roasting so forgive my potentially fundmental questions...

Logs (I hope I attached the images correctly) show overshoot (diverge and proceed with an offset) after CC.

All roasts L 3.0. 'default' and '15002000' (for file/image) refer to the profiles. If the image attachment works, then I'll also note that I manually dropped the REST1500 roast because it was already quite hot. I have to empty the chaff collector after every roast.

These are the 4th and 5th roasts with these beans, and all previous behaved the same. Tasting notes: still grassy (underdeveloped?) but also a bit of smokiness/ash (overdeveloped?). Even after resting for a 7~10 days, there is little 'coffee' smell, and a slight scent of ash; i.e. very mild smell.

How do I address the overshoots in the roast? Could that be causing the unbalanced flavour?

Thank you in advance for any questions/suggestions!

I’ve been hoping somebody might have some more info regarding your issue, as I have a similar issue that most resembles your first pic.

My Nano is an older (USB stick) model, and tends to overshoot from FC onwards on most profiles, and stays 1-4 degrees above the actual profile until the roast ends. Interestingly, I also have a newer (USB-C plug) Nano here temporarily, and with the same beans/profiles there’s no overshoot at all.

Both Nano’s have the latest firmware, are used in the same location.

The quality of the roast beans is better from the newer Nano, and to get similar (but not quite as good) results from the older unit requires the roast depth to be reduced by .1 or .2 compared to the newer unit.

Hi there!

having a quick glance, a few things spring to mind. The PID, whilst precise and very handy, is also sometimes stupid. It wont account for the fact that the roasting reaction will shift from being endothermic to exothermic around the 175-185 degree mark (meaning the beans will start radiating excess heat. This is also true bean temp, so the probe reading will be dependent on fan speed. Higher the fan speed, the larger the discrepancy between the shown probe temperature and the true bean temperature).

Adding in a corner (in the zones tab) or a negative boost/ power profile around this point might help (there are detailed instructions on how to do this in the kaffelogic companion booklet).

A little more advanced, but if you were comfortable tweaking the profile a little, i find a lot of the core profiles have a very short drying phase. A well planned drying phase sets you up for success later. Generally I aim for 40-50%. This will get the whole bean mass to a more consistent temperature before the browning phase begins (the probe might show a temp of 150 say, but the core of the bean is likely much lower in temp). The D Roast profile in the user contributed section is a great example of a profile with a longer drying phase.

Hope some of this was useful!

Very helpful, thanks for taking the time to reply. I’ll spend some time learning about your suggestions this week.
Thanks again.