Hi everyone,
I’m using a Bullet R2 Pro with RoasTime v4 and I’ve noticed that on some 1200g batches the IBTS curve starts reading lower than the bean probe well before first crack , not just near the end of the roast.
In this example, the roast is a 1200g washed Colombia batch:
- Roaster: Bullet R2 Pro
- Batch size: 1200g
- Coffee: Colombia washed
- Preheat: 300°C
- Drum: D9
- Starting power/fan: P11 / F2
- First crack: 9:12 at 198.6°C IBTS
- Drop: 10:45 at 209.3°C IBTS
- Development: 1:33, 14.4%
At around 7:58, the readings were:
- IBTS: 187.7°C
- Bean probe / BT: 194.7°C
- Difference: BT was about 7°C higher than IBTS
The part that concerns me is that the curves crossed well before first crack , not only during development or right before drop. First crack still happened at 198.6°C IBTS, which seems within a normal range, but I’m not sure if BT being higher than IBTS this early is expected on larger R2 Pro batches.
A few questions:
- Is it normal on the R2 Pro for BT to overtake IBTS well before first crack on 1000g to 1200g batches?
- At what point would you consider this a sign that the IBTS lens needs cleaning or that there could be an offset/calibration issue?
- Should I continue using IBTS as my main reference for FC and drop if FC is still around 198 to 200°C IBTS?
- For larger batches, do experienced R2 Pro users rely more on BT near the end of the roast, or still mainly on IBTS?
- Could fan changes, batch size, airflow, or bean expansion explain this kind of crossing?
I’ll clean the IBTS lens before the next roast and check firmware as well, but I’d like to understand whether this curve behaviour is considered normal for the R2 Pro or something I should investigate further.
Thanks.
