Thanks @da_kevin! Appreciate the feedback. I cleaned the IBTS just prior to roasting, so I agree, that doesn’t seem to be the issue. I did three roasts back to back (to back) and interestingly, the first two crossed right at FC, however, the third roast crossed at ~180 C. For what it’s worth, the third batch was an Ethiopian and the first two were Columbia and Brazil.
I received the 1/4 inch ceramic beads and did the experimental roast this morning.
I do not recommend that anyone try this. There were some not happy noises coming out of the Bullet. I don’t think that anything got damaged, but YMMV.
Here is a link to the roast:
Interesting results.
I did a 482 pre-heat and added the ceramic beans when prompted to charge.
The roast curve looked pretty normal in the beginning stages. I turned down the Drum rotation from D9 to D6 to make sure that the ceramic beans were not being held against the wall of the drum by centrifugal force.
The beans weighed 3 pounds but were about the same volume as 550g of Ethiopian beans.
At about the 14 minute mark the the IBTS and the BT were within 2 F.
The BT followed the IBTS very closely up until they crossed at 15 minutes and 450F.
The results followed what one would suspect where the BT probe slowly measures almost identical readings.
There was no stalling of the IBTS in relation to BT.
BT slowly increased above IBTS but only about 3 degrees in 3 minutes.
I think that this shows that the IBTS is measuring the surface of the beans when they are emitting steam and therefore the surface of the beans are cooler than the interior.
I think that this validates @deaddrift’s ChatGPT explanation of what is happening.
I think that this also validates @Blacklabs using the BT for the dropping temp.
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In that case, you might want to take a look at the Chaff Filter. If the IBTS Lens gets dirty too quickly, the Chaff Filter is possibly clogged and causing the smoke to come out of the Front (you’ll see excess smoke when you take out the Tryer during roasting). The Control Housing will be filled with heat, moisture, and chaff, causing the electronics to get dirty, overheat, or shorted.
You can take a look at the R2 cleaning video, which also applies to R1:
Best regards,
Kevin