Few burnt beans and how I fixed it

[sareea]

Hello all,
First of all I am really glad to join the community.
Thanks for all the contributors.
I want to share my first experiences with the roaster, please direct me to the right path however you see right.

Day 1: (I just created a good compost, lesson learned = read the roasting manual)
First 3 attempts, got few burnt beans each time no matter how much green beans I put, tried 120,110 and 100 grams (K-Logic Classic profile, Colombia).
I couldn't understand why until I lift the lid and saw that the initial fan settings are not moving the beans at all in the first minute.

Day 2: As a starter, read the roasting companion. The tips are gold
Tried in timer mode to check which fan speed moved the beans sufficiently and it was 170.
So I boosted the fan curve of the K-Logic classic to start with 1700 rpm, then decline to 1320 (the same as the classic).
Roast is now even, no burnt beans.

I guess I am in my steep learning curve at this moment,
Trying to tackle why my beans are exothermic and always a bit above the curve,
will play with the corner/zones/initial preheat and try.


Did you ever need to boost the fan up to 1700 ? Most of the curves I saw in the forum are 1450-1550 initially.

[Wayne]

Good day Sareea

I hope you are well - Wayne here from Kaffelogic .

Thank you so much for sharing your first experiences with regards to Kaffelogic .

I am happy that you are experimenting and figuring the Kaffelogic out . Before I comment , Id like to see a log or 2 that you have for those roasts . Just so I can have a little look and see if there is anything a miss with the coffee roasting . If you dont have any logs at this stage , NO stress . We might need to check a few things with you .

Please find my email address - [email protected] . I would need to possibly do a zoom meeting with you and assist you with better understanding how the Kaffelogic works. The aim is to check on one or two settings on the roaster.

Let me know if this is convenient for you ..

[sareea]

That sounds great
I Really appreciate tour help !
Just sent you the email with the logs

Attached them too

[Beanz]

This is a puzzle, Sareea and thanks for raising it here. It will be interesting to hear what the issue was.
While you are waiting for Wayne's reply, I just wonder two things:
1) I see you have updated to the latest firmware. It is possible the file or install was corrupted, maybe? Is it worth reinstalling that firmware or the previous version?
2) As it is a consistent issue, could there be a problem with that plug having too low voltage? eg other devices ( like coffee machines, toasters etc drawing on the same line?
These units, I've read elsewhere, are also not impervious to rough freight and something might have gone awry in transit?

Hope you hear back soon and it is easily resolved

[sareea]

Thanks beanz for the insight !

I dont think it is a voltage issue because the unit is able to draw 1200~ watts without stalling.
I am using an adapter converter (Aus to EU). It may be problematic, I will replace it anyway.

I am roasting at 1000m altitude, does that change anything?

Regarding the firmware, I will wait for Waynes assistance and will update with whatever we find.

[Geronimo]

Roast is now even, no burnt beans.

I guess I am in my steep learning curve at this moment,
Trying to tackle why my beans are exothermic and always a bit above the curve,
will play with the corner/zones/initial preheat and try.


Did you ever need to boost the fan up to 1700 ? Most of the curves I saw in the forum are 1450-1550 initially.

Hi

Was there an issue with your roaster, and what was the fix. I’ve always got burnt beans of varying degrees, and what I would call minor tipping always, no matter what profile used.

There is some movement of the beans be it minimal initially, but thought that maybe by design but doesn’t make sense, as when trying Damian’s D-Roast profile with a modified fan profile to get under the very frustrating power limitations that hamstring the roaster somewhat, I do get better movement, but have to say the beans go around more in circular movement and not so much vertical movement initially. It’s like the fan vents should be pointing more upwards to give the beans a bit more loft and fluidisation so to speak.

Anyway I’m interested to know what your solution was other than ramping up the fan profile.

Any chance of posting a video of your bean circulation initially for say a minute using the default K-logic profile, unmodified fan profile. If you can’t, no worries. No harm in asking.

Cheers

[Steve]

Agreed with your observations.

When using the lower rpm fan profiles, depending on bean size / density, as you lower the batch size say in 5g increments one hits a weight where there will be too much or mostly centrifugal spinning movement which will give uneven roasting.

The KL was designed with the idea that the bed will exist in a semi fluid state (bubbling phase) with occasional slugging where the bed jumps briefly. The lower rpm fan profiles at 100 to 120g do not reach this state until a few mins into the roast, there is some movement (minimum fluidisation) early on.

Problem is that contrary to wide spread beliefs, rushing room temp hard green seeds up past 100C in a matter of seconds just because you can does not mean its great for the overall development. Combine this with poor agitation and very high heat start can do a lot of damage and its not just the things you can clearly see.

The difference with Droast fan profile is that for 110g - 120g batch, the agitation at the very beginning is in "bubbling phase". As the coffee goes from yellow to brown with the static higher flow of air, the mass moves into a fully fluid state "turbulent fluidisation", like that of a commercial fluid bed roaster, which is perfect as the seeds enter the fragile phase approaching and through first crack.

Just to illustrate that I have observed a lot (right or wrongly) and nothing else. As of my last roast I have clocked up 127 heater hours. Which if you take say 10min as the average roast length = around 760 roasts.

My current thinking is that the only way to achieve the higher states of fluidisation within the power constraints of most peoples 230 - 235V is to use higher speed fan profiles with 120g but roast longer / gentle application of heat with a gentle ever increasing power profile. I had been chasing faster roasts / high speed fan using 85 - 90g batch size but keep running into the problem of the mass spinning. So it seems that larger batch sizes actually encourage better fluidisation as long as the fan speed is high enough.

So I might try some 120g batch size and 12 to 13 min med - light to med roast = + 10 to 15C past the temp of FCS. I gather this will be a bit flat as a filter coffee but has the potential to be delicious as espresso if done right (not baked).

All coffee roasting is just applying the right amount of heat in a way that brings out the best of the seed no matter what type of machine is doing the heating. The coffee roasters goal is to work out how best to do that withing the constraints of what ever machine they are using.

[Geronimo]

Agreed with your observations.

When using the lower rpm fan profiles, depending on bean size / density, as you lower the batch size say in 5g increments one hits a weight where there will be too much or mostly centrifugal spinning movement which will give uneven roasting.

Hi Steve

Fantastic explanation, and very much appreciated, as is all your comments and work that you have input to the group.

Interesting enough, you touched on 120g charge. I have also noticed that the weight reduces the spinning effect.

The D-Roast fan profiles modified for my voltage is definitely giving a cleaner finish. You made a positive comment to Damian relating to Scott Raos defect kit, and if you thought it was a good profile then that’s good enough for me to give it a go based on all the fan speed reasoning.

Not sure if you get mild tipping on beans or it’s just me (pre D-Roast)? I’ll post a typical photo at some point. I’m on an iPad and haven’t worked out how to include a photo. Im sure it’s easy?

I’m post blending the beans, and roasting typically just before second crack, and the left overs are used for long blacks. Up until D-Roast I have been getting all the not so nice tastes/flavours Damian talked about in one of his posts relating to his development of his D-Roast profile.

Thanks again

[sareea]

Thank you Steve

Hi Geronimo,
I am still working it out with Wayne,
He suggested to add 3 notchs to the fan caliberation.
I guess my roaster is fine, it is a little bit caliberation issue or a really dense bean. Or is it just me not knowing how beans should move, I was getting really burnt beans at the very start, even after 1 minute I saw the burnt bean moving between green beans, there wasn't any movement in the first seconds.

Regarding the video, it is a great idea to record the first minute, and I guess there should be a standard of which all of us point to regarding bean movement. I will post few videos soon.

I also get tipping , I currently don't know how to get around this issue, I read few comments that it is possibly bean related issue more than roaster related. And final taste should tel you whether something is wrong or not.

[Geronimo]

Regarding the video, it is a great idea to record the first minute, and I guess there should be a standard of which all of us point to regarding bean movement. I will post few videos soon.

I also get tipping , I currently don't know how to get around this issue, I read few comments that it is possibly bean related issue more than roaster related. And final taste should tel you whether something is wrong or not.

Hi

Thanks for quick reply and subsequent info. Yeah Steve’s a wealth of knowledge. Amazing how many hours he has done his roaster. And also impressed with Damian’s findings.

Cheers