First Time Bullet Roasting Issues. Your help appreciated


#1

First time roasting - on a Bullet or otherwise - and have some questions after my first non-seasoning roast today). Greatly appreciate the advice.

  1. FC according to IBTS was at 345 degrees. That seems very low from what I was expecting (I was expecting about 375). It was a Guatemala Patzún Finca Santa Anita. (By the way, I did 8 very dark seasoning roasts before this for a total of about 10 pounds. I add this in case you think I already need to clean probe). This roast was 450 grams in terms of batch size. Any thoughts on the low FC temperature?

  2. Perhaps not related to question 1 above (or perhaps related), I took the Scott Rao beginners course in May. He has a start up procedure that begins with a warm - up of 40 degrees above charge temperature, then gradually lowers the temperature over the course of some 40 minutes to the charge temperature.

Does the Bullet allow this flexibility?

I know how to adjust the pre-heat temperature - but only to the final charge temperature. The only way I know to work around is to set the pre-heat to 40 degrees above charge temperature, and when it gets there for the requisite time to then toggle through charge, roast, cool and shutdown and pick a lower pre-heat temperature, and then repeat till I get to the charge temperature I desire.

Scott recommends his warm up procedure for thermal stability. Any thoughts?

If there is no way to gradually lower the warm up temperature from 40 degrees above charge to charge temperature without the work around described above, , perhaps I should just put in the charge temperature and keep it there for 30-40 minutes?

How are others handling this?

I said above that question 2 might be related to question 1 because I am wondering if the IBTS bean probe is off and my keeping the pre-heat temperature for 20 minutes at charge temperature before beginning roast (I did not go all 40 minutes) resulted in a very hot drum and perhaps therefor the FC was really higher than the 345 degrees shown.

  1. I cannot toggle using button B between RoR and Drum Temperature. It does not do anything when I press it? Any ideas? I htink it is showing RoR only but not sure. It certainly is not showing the Drum Temperature

  2. Perhaps related to this is that one time during a seasoning roast - and not at start up - I got EC 0001. [No communication with induction module). It has not happened since.

Should I do anything since it has not repeated, and is it related to Question 3?

  1. The chaff basked is just about empty after each roast. All the chaff (or more than 95%) is in the compartment behind the chaff basket (which I vacuum out with a shop vac). Is this normal to have almost nothing in chaff basket and essentially all the chaff in the compartment behind?

  2. Is there a way after the roast is done to observe in RoasTime the percentage of DTR at various times instead of just the final DTR?

Many thanks from someone new.

Andy


#2

By the way, I guess in my question 1 above I should have mentioned how I am reading the Bullet Control Panel and the RoasTime software.

I understand (having a V.2) that

  • on the Control Panel the IBTS measurement is shown as Bean Temperature.

Accordingly, when I said above that FC was 344.8, that is because in RoasTime “Bean Temperature” at FC is shown at 344.

However, if the Bean Temperature on the Control Panel is the same value as shown as IBTS Temperature in RoasTime, then what is “Bean Temperature” in RoasTime? Is it Drum Temperature? If so that seems needlessly confusing. Why wouldn’t the RoasTime software call it such.

But if IBTS Temperature in RoasTime does equal Bean Temperature, at least it would explain the value I got for First Crack on my first roast. It would be 404 (probably caught a little late) and not 344.8


#3

Hi Andrew

Welcome to the gang. If you have a browse around previous topics you will see that not all of us are convinced that all of Scott Rao’s suggestions/observations apply in full or part to the Bullet. It’s a different animal to a heavy thermal mass production (gas powered) roaster…so some of his “build up momentum” stuff doesn’t apply. We/I have likened those roasters to oil supertankers needing to think ahead minutes whereas the Bullet is more akin to a speedboat due to the smaller thermal mass and induction heating.

One thing that sometimes seems to come up is the “tail wagging the dog” syndrome - if I have a perfect Rao RoR then I must have perfect tasting coffee right ? Well maybe not. I think the best thing to do is just experiment and then when you find a coffee that tastes primo, look back at the trace and work from there. It’s more fun too ;0


#4

Thanks. I have indeed seen illustrations of your point.

Having said that, do you know if there is flexibility to work one’s way down to the charge temperature, or is it basically set one pre-heat temperature and then charge when hit (or after waiting a little while at that one temperature)?

Many thanks.

Andy


#5

I’ll give your list a shot…

Using IBTS (that’s clean), I’d expect 1C at around 400°F

On the first roast of the day, leave the Bullet on Preheat for 45-60 min. You’ll go nuts listening to “Charge!” for 40+ min, but that’s what it takes to not make the first roast an outlier.

re: IBTS… early in the roast IBTS will be 35-45F° higher than Bean Temp

Won’t happen till the roast starts. During Preheat it stays on IBTS/Drum Temp. Keep in mind that Preheat uses IBTS to hit the set point. The only thing Bean Temp has to do during Preheat is stay stable.

I’d suggest contacting Aillio Support to start a Trouble Ticket (aillio.com -> support). Yours is a new roaster and there might be a loose connection or… ?? They’ll guide you thru it.

What you called the chaff basket is the chaff filter. It blocks chaff from being sucked out of the chaff collector (the left half of the rear of the Bullet) and getting blown out of the Bullet. You can vacuum the chaff out of the collector thru the trap but you’ll also need to periodically remove the filter/basket to clean it with a citric acid cleaner & brush (you should use rubber gloves). Also, after a roast session you should think about doing a thorough job vacuuming the collector.

I’ll have to leave this for someone that understands it.

Bruce


#6

Hi Andy -

Welcome! Starting by taking Rao’s class was a good move.

The names for temperatures are confusing (to me anyway). I wish we’d just always refer to them by sensor, for example “IBTS” and “probe” (or “thermocouple”, or “TC”,…). I always roast with RT connected, and just pay attention to the upper blue IBTS curve. Sounds like you may be looking at the temperature display on the Bullet more than I do, which might add confusion.

Re: #1, my last Guatemalan reached FC at 200C (392F) IBTS, 176C (345F) probe. So looks like you were reading probe temperature. I’ve found that 200C IBTS is a surprisingly reliable FC temperature for many different beans.

Re: #5, I’ve been cleaning the chaff screen filter after each roast by removing it from the housing and scrubbing it gently with a toothbrush under running water. This takes literally 30 seconds and after ~25 roasts my filter still looks new. Caveat that I haven’t been roasting beyond the first snaps of 2C.

Re: #6, I think I know what you’re getting at. Some of Rao’s milestones are based on DTR percentages, and it would be nice to review a roast and interactively query DTR. AFAIK this can’t be done in RT. DTR is displayed in the little box at the top of the screen while roasting, but it isn’t available afterward. If you find a way please shout it out.

Hope this is helpful.

Cheers,

  • Brad

#7

Thanks for your thoughtful reply.

Several questions/comments:

  1. I get the idea of using the IBTS probe as the bean temp, but when you go back and look at your roast using the analyzer function, or just lookIng at the software generated roast profile, it does list the bean temperature at FC as the thermocouple sensor value. Not the IBTS value. Very strange. I agree with the terminology preference of bradm below.
  2. It seems “early” - based on the grams of beans I have collectively roasted so far - to have to clean the IBTS probe?
    But of course I am willing to do it for the sake of accuracy.
  3. My problem with toggling occurs even during roast, so I guess I will need to contact Aillio about that as well.

Thanks again for the prompt reply.

Andy


#8

Thanks for the great feedback!

Andy


#9

re: IBTS for tracking roast progress… yes, Analyzer uses the t/c probe but it does include IBTS in the array of data. The t/c probe should be very consistent and as close to bullet proof as an electrical measurement can get. IBTS can get dirty and some roasters are more susceptible than others. Mine seems to be prone to contamination which causes a gradual shift in data (in effect it’s an offset error). I did have a bad IR sensor fan motor (the fan runs at 16,xxx rpm and blows air out the IR view port to keep contaminants from getting in) and had hoped the issue would go away when I replaced it but no joy.

In terms of reliability of measurement, I hate to say it but the t/c is probably the most repeatable. I happen to have some data collected from a t/c in an old Probat that almost exactly replicates (a recently cleaned!) IBTS data. I got hooked on that as it gave me a reference that I felt I could trust. So it’s just a personal preference that requires some mental arithmetic on occasion and more frequent fussing with maintenance.

re: when to clean the IBTS… yeah it’s probably too soon to have to clean the IR sensor, but if you watch the IR & t/c curves when they’re running parallel at say about 3:xx min into the roast and keep track of that difference (pick it off the charts after the roast), that should tell you when to clean the IBTS. The change is gradual, not sudden. Keep in mind that Preheat uses IBTS exclusively for setting the target temp. If you accumulate a sizeable offset error in the IBTS, then there’s a gradual drift upward in final Preheat temp over a period of time.

re: toggling the IR & t/c data… I doubt there’s an issue but rather me misinterpreting what you see plus not properly recalling the display. I use RT almost exclusively so I have very little interaction with the control panel except to silence the dead-man alarm (A-02), plus start or stop Cool mode, and to restart Preheat for back-to-back roasts.

Bruce