luca wrote:So what we want to know is if you can get a roast of less than, say, 5 or 4.5 minutes and have the coffee sort of popping along aggressively as opposed to barely cracking. If it can do that, then the voltage on the US version probably isn't going to be an issue.

Did a roast, results post #9: Kaffelogic for the USA is on Indiegogo

First crack started to roll but the profile has it slow down so it wasn't an overly enthusiastic roaring first crack. Entered first crack around 9.6F/min. Let me know if you think I should push harder/darker. This was 90g batch. 125g would stress the unit more but Kaffelogic is going to release their BOOST package sometime soon and that will up the batch size to 200g I believe and that should make these 100ish batch sizes a breeze even if one wants to take them quite dark.

I thought Sweet Marias or Coffee Shrub had some airflow articles but I can't find them anymore.

luca wrote:Maybe a better example is frying. Let's say you get a really heavy, massive, cast iron skillet and you heat it to, say, 250C. And you also get a piece of aluminium foil and heat that to 250c. Then you cut the heat and put a steak on top of each. Both are at 250C, yet clearly the greater mass of the cast iron skillet is going to cook the steak more than the foil.

Your cast iron skillet sounds like a drum roaster . Not sure if I understand the application of what you're saying. On these small fluid bed home roasters my experience has been that more air needs more heat, and the higher heat causes more momentum. Charging hotter also causes more momentum. But lower fan gives a less uniform roast--beans on the top tend to stay on the top. Beans shedding weight improves airflow, and a fixed fan setting moves the beans more at the end than the start, which is good for me because I don't want uncontrollable momentum at first crack. Still not sure if I understand you correctly.

One thing about the Kaffelogic that I haven't wrapped my head around yet is the cooldown and how it essentially cuts the heater and ups the fan, but the beans are still in the roast chamber, so that first 1 or 2 seconds of cooldown takes all of the residual heat from the heater and blasts the beans when they are at the end of the roast and at their most vulnerable. According to the log file, the bean temp drops precipitously once cooldown starts, but I don't know if I trust the probe, just a theoretical observation at the moment, not sure if it's factual or relevant.

ducats wrote:On these small fluid bed home roasters my experience has been that more air needs more heat, and the higher heat causes more momentum. .

In an oven if you add a fan, making it a convection oven, they tell you to reduce the temp 25 degrees F because the fan delivers the heat better. But this was a big mystery in working on the FreshRoast for me, not knowing it the increased fan just meant my TC was reading more of the hot air and less of the relatively cooler bean. Plus I was reaching max heat or really finding that the fan simply had to be adjusted to keep the bean height correct, instead of adjusted to change the profile. It's all too confusing to me. Which is why I appreciate those of you doing all these experiments and I hope they find their way into good Ikawa profiles for me!

So that's right? Increased air needs increased heat?

MNate wrote:So that's right? Increased air needs increased heat?

If you want the same roast length and you increase fan you will need to increase heat. Though there might be some confounder variables at play. I'm largely talking about roasts where the fan setting is the same all the way through. Minor tweaks may not need a corresponding heat adjustment.

I've never roasted on the FreshRoast or Ikawa but I stumbled across this from Crown
https://royalcoffee.com/roasting-on-ika ... ks-tips-2/
"You'll definitely lose a few beans during roasting while you're at 80% or more fan speed." This isn't a problem with the Kaffelogic, there's no cooling bin/jar. I downloaded the Ikawa app a few days ago to look at the profiles and most seem to slowly decrease fan at a constant rate, maybe to protect against this quirk.

luca wrote: Matt Winton's profiles are around that time (or even shorter) for Roest, I think TW was also lower in roast time. The idea with these roasts is to have something that is very acidic, very sweet, very clean, zero bitterness, zero roast flavour (eg. char or toast/bake) and well-developed acidity. My usual roast defect is underdevelopment.

Found these With the profile for the washed coffee he went something like 1 degree C in DEV according to the Bean Temp and 7C according to the air temp. I'm not sure how to interpret those. Seems very, very light. Wish he mentioned percent loss. My 9.8% loss has me strongly suspecting it will be underdeveloped and my stomach does not appreciate those. I did a second 5 min roast, same beans, and got 10.48% loss, but I went 10F. ROEST might have more thermal punch, plus with the Kaffelogic unable to do a charge temp higher than ambient, I'm not sure what comparisons can be made.


TW's profiles seemed to be more for just farm samples and cupping than for filter. He says ROEST makes their own probes because even sourced from the same company there was too much variability in the readings. The Kaffelogic probe is noisy. Manual says to set smoothing to 30 seconds. It needs it. What's the ROEST set to? I haven't researched the ROEST much because I saw its price.

Cools, thanks for doing that. That profile looks like the power wasn't flatlining and the target temp and actuals were tracking well, so the machine wasn't lacking for power. You were able to get there sort of at least with a 90g roast, so it sort of suggests that the 110V machine probably isn't underpowered, which would be the main concern for a 110V buyer, I'd have thought. I have no idea what this boost ... sorry, "BOOST", thing is going to be, beyond the glass roasting chamber, but one would think that, for the 110v KL, at least, there might be power limits that need to be addressed for a 200g roast. Maybe they have some firmware update to remove some internal limit to the power allowed through the element? Or maybe the 200g roasts simply take quite a long time?

TW's profiles seemed to be more for just farm samples and cupping than for filter. He says ROEST makes their own probes because even sourced from the same company there was too much variability in the readings. The Kaffelogic probe is noisy. Manual says to set smoothing to 30 seconds. It needs it. What's the ROEST set to? I haven't researched the ROEST much because I saw its price.

I'm not quite sure what this question is, but the Roest calculates ROR over a 30 second span. I don't know about software smoothing for the individual readings. Yeah, the roest is pretty over the top. I won't post photos of the probes that they sent me, but they had gone to the lengths of not only building the probes, but building electrical interference insulator housing for them. I'm kind of trying not to veer off topic, though - this is about the new KL, not the roest; the relevance of the roest is that it also uses hot air and I can use it to illustrate some of the concepts relevant to the KL to raise questions for people who are interested in the roest to look into and fix. FWIW, I got a very lucky deal on the roest. I've seen all of the stuff that you're linking, have experimented with all of their roast profiles and have been in touch with TW and Matt Winton on it, as well as Ben Symes, who is the head roaster at TW. If you want to discuss more of that stuff, perhaps we should start a separate thread, but I'm not pretending that I know how to get great roasts out of anything. I don't really know what distinction people think there is between cupping roasts and filter roasts. I mean, the true distinction between the two is really that with cupping samples, you usually don't get lots of goes at it, so cupping roasts are often a little bad. But if you asked a roaster what they were aiming for in a cupping roast, I think many of them would probably say they'd take a filter roast if they could get it.

Anyway, back on topic. Here are a few graphs from the roest. The first one is a graph of a roast of 100g of Kenyan coffee. Worth noting here is the difference between the "air temperature" probe (yellow) and the "exhaust temperature" probe (light red). These probes are positioned in the roast chamber, on the exit side, partially on the other side of the green coffee. You can see that the small difference in positioning results in very different readings. The bottom one is a graph of what happened when I lowered the target temperatures, based on "air temperature" by 10c and loaded double the load into the machine; 200g instead of 100g. You can see that even though the "air temperature" was supposed to be far lower, it's measured on the other side of the green, and there was tonnes more green there, so the inlet temp (top reading in both) went off the charts and I even ended up manually taking over. Also, there's this bizzare phase in the middle where the bean and air temps all drop! The 200g roast rocketed along and ended up being really roasty.

I'm posting these graphs because people seem to just assume that temperature readings are meaningful and comparable. But in actual fact, particularly with these high airflow hot air roasters with small weights of beans in them, there is tremendous variation depending on probe positioning, bean load, probe sheaths, etc, etc, etc. You can do a pretty easy thought experiment in the KL, or even an actual experiment (Steve and I did this) - imagine you took the KL probe and just bent the sheath down to position the probe lower in the bean mass, or even positioned it in one of the hot air vents. The probe would be positioned in the bean mass, but the readings would be a lot hotter. In fact, from memory I think Steve even had a go at moving the probe to an inlet to try to get inlet temp control, but the problem was a software/firmware limit on temperature for safety wouldn't allow him to set high enough temperatures (since the high temp ceiling is set assuming the higher probe position).

I'm wondering if anyone with an IKAWA Pro has experience with the Kaffelogic.

I'm considering purchasing the Kaffelogic vs the Ikawa Pro for experimenting. I already have a bullet but I can't afford to experiment and learn with larger batch sizes. I want to test roasting theories and experiment for myself.

In terms of the Ikawa, the home version seems to provide too little control and feedback for any serious learning. However, I wonder how the Kaffelogic stacks up against the Pro.
What is the smallest/largest batch size that the Kaffelogic can do?
How much data and control does it have vs. the Ikawa Pro?
I do not plan to transport the Ikawa Pro so the pelican case is not valuable for my use.

Is there any other considerations I should think about before deciding whether or not to back the indiegogo campaign?

Here's one more thing to illustrate the lack of reliability of temp readings. Two roasts of the same coffee, same profile (based on "air temp"), but one was at 30% fan, one at 75% fan. Pretty much the same BT and air temp readings. Inlet temp ~15-20C hotter for the 30% fan roast. Lower fan hit first crack a little later; ended roasts at the same time and BT reading; lower airflow coffee looked and tasted darker. And, yet, if you were blindly relying on ET or BT readings, you would think these roasts were identical. So this is where it's easy to get lost in tail chasing based on assumptions about what the temp readings mean.

hairyco wrote:I'm wondering if anyone with an IKAWA Pro has experience with the Kaffelogic.

I don't, but the obvious difference is that the Pro has two probes instead of one; see my posts above for how this might be helpful.

I went from a Home to a Pro. I don't think that the pro is conceptually a superior roaster, but having the second probe and being able to define a profile on either the inlet or outlet makes working on profiles ever so much clearer. Once that's done, I'm guessing I could easily set a Home up to duplicate a Pro profile. It was a lot of money to make that upgrade, the Pro is over triple the cost of the Home, but I'm certainly much less frustrated with the Pro and while I've no idea how optimal my current profile is, I'm drinking better coffee than most of what I've purchased over the past couple of years.

hairyco wrote:I'm wondering if anyone with an IKAWA Pro has experience with the Kaffelogic.

I'm considering purchasing the Kaffelogic vs the Ikawa Pro for experimenting. I already have a bullet but I can't afford to experiment and learn with larger batch sizes. I want to test roasting theories and experiment for myself.

Im Steve who had the KL and went down rabbit holes with using different probes and positions / tearing the machine apart.
Hard to disagree with any of what Luca has written and people should manage their expectations.

I have some experience with the Bullet. Buying any small air roaster will not help inform your bullet roasts in any shape or form. Rob Hoos recently wrote a great article for roastworld about 150g sample roasts on the bullet. Assuming you have newer model with IBTS, this makes the 150g sample roasts even better at informing on what decisions you will make on larger batch sizes.

For reference my roast preferences align reasonably closely with Luca. TW light roast, Manhattan filter, Passenger and hit and miss with SEY over 1 year subscription with regards to being a bit under for my preference. But I also roast a lot of longer darker roasts for other people and have done so / tested many 1000s of this style, so I can set aside my "filter" style preferences. From memory the KL could do a pretty decent job on darker espresso roasts and there is a lot of happy people using it for this purpose, a major upgrade from stale supermarket roasts.

I also agree that this idea of a "sample" roast quality does not matter, its just to inform green buying etc is not great. Rob touches on this in the roastworld article. When you start making small "profile" adjustments to a sample roast so that its not defective and delivers a light, aromatic and sweet filter brew whats the difference?

This in essence was what I was trying to do with the KL and would happily pay to buy some roasted coffee that would stand up in a blind cupping. I have no problems with being proven wrong and turn out I just didn't know enough about how to use the roaster.