IBTS Problems

Taking Care of the Bullet R1 Bullet R1 Troubleshooting
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When I got my Bullet, roasting using the IBTS was a revelation. I was very impressed with the repeatability it brought to the game. Per Morten Munchow, I’d do an establishing roast for new varieties of beans and find out at what (IBTS) temps FC and SC happen and then engineer my subsequent roasts from there. Irrespective of my charge size, FC was very nearly the same temp every time.

This continued for dozens of roasts and, with occasional cleanings, I was a happy camper.

However, over the last few months, the IBTS has been apparently getting dirty very quickly. Now, I can do a thorough cleaning and the IBTS vs bean temp behaves as it always has. By the second near back-to-back roast (I move directly to Preheat as soon as the last batch of beans is cool), the difference between the IBTS and bean probe is getting smaller. By the third or fourth roast the bean temp crosses the IBTS temp and by the fifth, the IBTS is completely useless and I have to clean it again.

I know it is the IBTS underreporting the temp because, if I let the roast go to the desired IBTS temp, it is badly overroasted.

IBTS fan is showing in the high 15K’s.

Have taken apart the front panel several times and the IBTS fan is clean, the assembly well seated and nothing appears to be amiss.

I am good about otherwise cleaning the machine. Impeller is reasonably clean and freely spinning. The small fan at the back of the drum is freely spinning.

When I take off the front plate to clean the IBTS (yet again!), the front plate is not particularly dirty, though it is kind of dusty. Maybe the IBTS porthole is kind of dusty, too.

As usual, the cotton buds that i clean the sensor with rarely show much of anything.

It is my impression that the area under the drum accumulates more chaff and other schmutz than it did in the past. I blow it out after every roast.

My typical roast is -
500g
PH - 250°C
P8, F2, D9 to 2:30
P5, F2, D9 to 200°C
P3, F2, D9 to dump, usually somewhere near 215°C.

I am ready to replace the IBTS assembly, though I can’t really come up with a fault that might explain this behavior (and the engineer in me demands one!).

Thoughts, anyone?

Thanks!

-Gray

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Hi Gray,

If your IBTS gets dirty really quick, there are two things you’d wanna check:

  1. Make sure the IBTS Module is aligned correctly with the IBTS Eye.
  2. Clean the Chaff Filter.

You should soak the Chaff Filter in some hot water with baking soda or cafiza, and then scrub with a metal brush. If the Chaff Filter appears to be black, then the mesh is covered with oil, and the airflow is blocked. Poor airflow causes the chaff to blow back to IBTS.

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On top of that you can try the beta version of the firmware (610) which helps with this problems.

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Other than cleaning the chaff filter , my personal experience that the minimum fan speed I would use is F3. The reason being that is in my case with a fan speed at F2 there will noticable smoke coming out of the trier when at higher temp during the roast.Another good old way is to use a lighter at the trier openning and watch the flame direction. So you can have an idea how strong the pressure is creating by the fan. With enough pressure to blow the hot air (smoke) out is important to me. As to me, that will influence how IBTS is telling me what temp is.
Also, if the fan speed changed, your roast profile may also be affected thus creating a stronger delta between IBTS and BT reading.
But again, that is my personal experience with Bullet for 3 years.

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Thanks, all, for your replies!

I am careful with cleaning and the chaff filter is near spotless.

I have avoided upgrading firmware until I stop hearing about problems on the forums. The current version has worked quite admirably for over a year and does all that my limited needs require.

I’m aware that one feature of the newer firmware is slow fan during preheat to reduce schmutz buildup on the IBTS, but this is a problem of fairly recent development (and getting progressively worse). I went for months and dozens of roasts without requiring but occasional cleaning of the IBTS. At this juncture, the IBTS is basically only useful for one or two roasts before it needs cleaning again.

Almost all the roasts I’ve done have been at F2 (and I DO see a small drift of smoke out of the tryer hole later in the roast) with only occasional forays into F3 or F4, if I need to slow down a roast.

Not sure why things are different now.

I will try rejiggering my roast profile to see if I can reliably meet my milestones at higher fan speeds.

Thanks, again!

-Gray