Hi I have had this happen a couple times now, when doing multiple roasts. Seems to show up on 2nd and 3rd roasts. I’ve included some screen shots of three consecutive roasts, plus another done on an earlier date showing the graph from a similar roast for the Guatemala. You can see a similar roast profile but the IBTS line is erratic. The last time this occurred I cleaned the sensor inside the roaster (less than a month ago). But it happened again in some very recent roasts.
I’m not sure this is an issue that will completely go away. I just did a deep clean last weekend. If I roast this weekend I’ll post. I know my last roasts prior to the clean does have some wiggly IBTS RoR lines.
Are any of you still experiencing this issue? I’m seeing the same pattern in some (not all) of my recent roasts. For me, the oscillating ROR is more pronounced in the later of sequential roasts.
@jimecunninghamfs5o interesting you bumped this old thread. I did 5 roasts yesterday (after a deep clean a month ago and hadn’t roasted since) and noticed the oscillating pattern as well in the last 3 roasts being quite pronounced esp the last two which were 1lb roasts (the other 3 were 1.1kg roasts), but didn’t pay too much attention to it until I saw this post of yours. I went to look back at many of the past roasts and this “problem” is much more pronounced with my ~1lb roasts.
I’ve been ignoring that in the beginning part of the roast and focus on the latter part. The software tracks every data point and doesn’t smooth out the curve so we’re going to see a lot of this.
My main concern is whether the data is real or not. Do the oscillations indicate a malfunctioning temperature probe or rather realistic temperature conditions that just need to be understood?
No malfunction; normal stuff. I don’t know how much you care about the details, but…
I-RoR is an approximation of the 1st derivative of I-Temp… essentially I-RoR tells you how fast I-Temp is changing value; i.e. not the value of I-Temp but how fast I-Temp is changing. Notice the wavey characteristic of I-Temp early in the roast above: I-RoR is confirming those temperature swings with calculated values for how fast the temperature is changing.
If you find it distracting you have a couple options in Settings:
turn off I-RoR and use just B-Temp and I-Temp to roast; alternatively…
change the scale of I-RoR in settings so that it doesn’t have such an exaggerated swing.
In RT4, click the user icon and choose Edit Settings. Then click Roast Config and choose Chart Defaults at the bottom. The Y2 axis is what controls the scale of I-RoR. Here’s how I have it set-
… which suits my purposes. If I wanted to get I-RoR onto the chart earlier I would change the Y2 setting in Roast Config. A larger number will get I-RoR on-screen sooner while a smaller number will have I-RoR off the chart longer.
Note the move away from a linear decline of both RoR curves starting at about 9 min. That’s not what I want but goes with the summer season: room ambient in the summer makes the heat loss significantly lower in that stage of the roast. The cluster of Power changes at that time was me doing a poor job of trying to compensate. During the winter season that is less exaggerated (roasting coffee in SE Arizona summer is… a challenge).
Also in the screenshot above you see the option to not display I-RoR at all… just set IBTS RoR to the left (grey) to remove that part of the roast display. Possibly not a good plan if you ever ask Aillio for help and that function is missing from the data.
I am new to this issue unfortunately. I understand it may be normal, but if that was the case it should happen consistently. The fact that most of us experience it every few roasts seems to indicate an issue.
Has anyone made any progress on understanding the root cause, resolving it, or just accepting and living with it?
I was about to make my own post about this, but I saw this post and I have the exact same issue as the OP so I guess it’s good to know I’m not alone
I was wondering if it was related to the latest update of RoasTime (which updated for me today) but seeing these posts makes me doubt it. I’ve had this happen when doing really small batches (~150g) but that makes sense because there’s not enough bean mass to accurately measure consistently. Today I had the issue with a 700g batch and it was my first time seeing such wild swings with a batch that size. That should be plenty of bean mass for the temperature to get a consistent reading, right? I’m roasting on a fairly new R2 (~28 roasts including seasoning)
Smoothing might be good, but not smoothing helps with resolution.
Once a small bean got stuck between the drum and the door, and I saw the change in temps very quickly. Another time the bean chute plug was dislodged a little and I noticed the temp changes very quickly.
If there is an over zealous smoothing feature added to the roast curve it may prevent detecting other anomalies.
I think the issue is the IBTS is not accurately reflecting the gradual increase in bean temp. There is no way a constant application of heat to the beans would cause IBT to rise in a stepped fashion resulting in the ROR swings. Not sure if this is algorithmic or what.
Having scanned my whole roast log, the issue only started to happen 3 months after I started using the Bullet (unless I was roasting smaller samples, where it was always the case) and currently it is significantly most pronounced in the first roast of the day, smoothing out from the 2nd onward. So I’m not sure if it’s an issue with the sensor.
I don’t know if our issue is the same, but we had our mainboard changed a couple of months ago from one that we have been using since 2020. The previous board was a workhorse and was easily handling 1.05KGs with enough oomph for us to play around with Power, Fan and Drum for roast profiling.
The new powerboard has a CE certification sticker on the side, a new cover but is comparatively less powerful than our old one. Preheating to 310C took about 14 mins for the IBTS to show 310 and beyond. The same happens about 3/4 minutes later at about 18mins. Compounding the issue is the IBTS that fluctuates wildly, so much so that the readings reach a certain temperature, say 160C and then it goes back sometimes by about 5C or so and then back up to the previous level, a few times in each roast.
Had a long exchange of emails with Matt from Aillio, sent profiles suggested and at the end, was told that either the Bullet be sent to Taiwan for calibration or I had to reduce my load to 850gms or so. I am doing that but the wild fluctuation has not gone away. In fact, I am now using my Bullet, which I used to talk so highly about like a Gene Cafe at P9 throughout. Any decrease in power and the roast targets are not met. It has basically been a tragic fall from grace from one of the most capable and intelligent roaster to a dumb one with no use for all the controls.
Unfortunately for the R1, changing the power board will cause it to not be calibrated, as the calibration requires the specific coil, board and drum to be present.
In production, every Bullet is running on a calibrated power supply which we use to tweak the power, so each Bullet match. The R2 is different as it can auto calibrate itself without the use of external hardware.
We are developing a piece of software which will allow you to calibrate new induction boards at home, but it requires you to get hold of a power meter.
I will have Matt reach out to you about this option.
About the IBTS fluctuations, can you try running D9 and check if this helps?
I’ll chime in, but it will mostly be ramblings of a mad man out of which someone smarter than me could come to some sort of conclusion. This did start happening towards the end of 2023 on my machine. My only conclusion so far is that the Bullet does not preheat properly and has an unstable temperature before the second roast. Now, I also think that this is happening to many owners of the Bullet, but it’s very close to a non-issue, as bab says above, so nobody reports it. I’ll put myself in that category. I can’t see the history of changes in various firmwares, maybe because it is not a click away and I’m too lazy to dig for it, but it seems to me that this started happening after the introduction of F1 during preheat, which was somewhere between 601-605. That small change has also impacted my approach to roasting the first batch because the machine started behaving differently. I did ask about that and got a very good reply explaining what exactly happens. Here’s the link.
What I also noticed is that soaking exacerbates this behaviour. If you hit it with P9 right out of the gate, it should be a lot less, which might not be true, but it is what I think after analyzing all my roasts. As noted by magneticfede the smaller the batch, the bigger the fluctuation on first roast. But, as it turns out, people who roast 1kg batches have this too, so I’d go to previous heat instability due to the different preheat routine. Also supporting this theory is the fact that it smooths out towards the end when everything gets hot enough, as pointed out above by bab, who also explains how the I-RoR is calculated and reflects the swings of the I-Temp curve. I don’t know if there’s a solution for this, but I’m pretty certain that there are no failed parts in your machine that need changing.
Well, that’s my 2, or maybe more, cents. I don’t know if it makes any sense, but now that I’ve typed everything, I’ll just click on the blue button.
