Kaldi Wide Mods: Thermocouples and Airflow

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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dominico
Team HB

#1: Post by dominico »

I'll preface this by stating that I'm not a very experienced roaster, and the only other coffee roaster I do have experience with I also built.

Also forgive the lack of fit and finish: I consider myself an above average prototyper but once I get something working reliably I don't always get around to "phase final" of the projects.

So I was relatively happy with my "turbo oven drum roaster" but I ultimately felt it was limiting in its potential for roast profiles so I decided it was time to step up my game a bit.

I ran across a South Korean roaster called a "Kaldi Wide" which is the typical "set it on top of a heat source" small drum roaster. This one comes with a funnel, trier, bean temp probe, and DC motor to rotate the drum.


I've been doing some reading into roast profiling and learning all sorts of neat things that I couldn't do with my trubo oven drum roaster, so I decided my Kaldi Wide would also need to be fitted with BT / ET thermocouples for roast logging in Artisan as well as air flow control.
Taking a hint from the Huky I thought it would be cool if my air flow control could double as a been cooling station when the roast is dropped.

I got a Phidgets 1048 to interface the thermocouples to Artisan.
For the Bean Temp thermocouple I decided I might as well remove the bean temp thermometer and replace it with the thermocouple. The hole sizes don't match so aluminum tape to the rescue.




For the Environment Temp I removed a screw from the backplate: the ET probe is just small enough to fit in there.



The Kaldi Wide has some vent holes above the drum; but in order to have proper control over air flow and properly vent the smoke I needed to cover those up: so I did.



For the fan I decided to go with this 6" duct fan. Part of the reason I chose him is his high CFM rating (for a duct fan) and the fact that he has metal and not plastic fan blades. It also works decently enough with this fan speed controller. I say "decently enough" because the operating range is basically from full blast down to the lowest "high" setting. Any setting lower than that and the fan simply stops spinning. Still, this is good enough to give me rudimentary air flow control inside the roaster and kick it up to full blast when needed.

I also started making fancy tubing with with stainless steel tubing I found on Amazon / Jegs, but got impatient and went with a hole saw and dryer venting instead.



Judging by my anemometer (air flow meter) readings it works just fine; even if it looks just absurd.

After putting it all together, it works! I haven't tasted the coffee yet, but it looks nice and evenly roasted, and actually using the trier was fun. Also, the majority of the smoke vented out through the ducting and the smoke was well under control, which was very nice.




I also got to play with how the air flow affects the roast through the Artisan logging. I have a feeling my roasting competency is going to increase significantly this summer. I'm looking forward to it.
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Il caffè è un piacere, se non è buono che piacere è?

DanoM

#2: Post by DanoM »

I'll be following the Kaldi Wide info. Might have to pick up a drum roaster in the future, and this could be on the selection list.
LMWDP #445

rittem1

#3: Post by rittem1 »

I have been interested in the Kaldi roasters for a while and it's cool that your mods have at least attempted to deal with some of its shortcomings. I notice chaff everywhere. Is that from your cooling process or is it flying all over the place during the roast?

Looks very promising and I will following along as well! good job
LMWDP #517

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dominico (original poster)
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#4: Post by dominico (original poster) »

rittem1 wrote:I notice chaff everywhere. Is that from your cooling process or is it flying all over the place during the roast?

Looks very promising and I will following along as well! good job
The chaff was actually very well contained during the roast. I just simply forgot about the "chaff catcher" and any chaff in my air hose so when I went to drop the charge in my super fumbly manner I threw the chaff all over the place. If I take a bit more care next time the mess should be greatly reduced.
http://bit.ly/29dgjDW
Il caffè è un piacere, se non è buono che piacere è?

hansfranz

#5: Post by hansfranz »

Great mods! I just got a Kaldi Wide and finished up a handful of seasoning roasts over the weekend, first real roast tonight! I'm coming from heat gun roasting so the idea of having any kind of temp gauge is great, but I've already started thinking about adding thermocouples and controlled airflow/chaff collection. I hope you keep posting updates cause I'm looking forward to seeing how everything goes for you!

I imagine the flexible vent hose will be easier to manage in some ways, considering the need to remove the hopper/trier/BT probe assembly when you end a roast.

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dominico (original poster)
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#6: Post by dominico (original poster) »

I am planning to post some of my artisan profiles, i just haven't gotten around to it.

The "drop" is certainly a little clumsy, especially because the aluminum hose I am using that I have to remove is hot AF when I take it off, and I have noticed you have to tip the Kaldi back slightly when you remove the hopper trier or the beans start to fall out.

Other than that I am loving the setup and I don't know if I could ever go back to roasting without thermocouples and temp profiling software!
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Il caffè è un piacere, se non è buono che piacere è?

hansfranz

#7: Post by hansfranz »

Artisan and profiling will be a whole other learning curve for me once I get the basics of the Kaldi worked out!

Yeah the beans falling out thing is annoying, but with a low profile enough cooling tray (I use a stainless 10" flour sifter) I can get the tray close enough to the front of the roaster that any escapees land in there. Long term I'm thinking about building a base for the Kaldi that encloses my heat source and holds the roaster a few inches higher than my cooling tray, then I can put the whole roaster in hinges so it's easier to empty (like a Probat/Jabez sample roaster).

Maybe you can wrap part of the aluminum hose in silicone insulation or something like that? At least to give you something to grab onto.

pcivic

#8: Post by pcivic »

Hy,

I am also very interested in this roaster. I have a few questions

How do you like taste of espresso comparing to your previous roaster (I also have DIY roaster and I am considering kaldi wide)?

What would you say is max recomended batch size to still get good results for this roaster? Probably 300g is to much? How many grams batch do you usually do?

Could you provide maybe some pictures of roasts with kaldi wide?

And maybe experience after few weeks still happy with performance?

Thank you a lot for help! :)

Felice
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#9: Post by Felice »

Is the wide different than the kaldi that's been around for a bit (a year or so?) Also, I am very curious as to the difference with forced air vs not forced air.

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dominico (original poster)
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#10: Post by dominico (original poster) »

pcivic wrote: How do you like taste of espresso comparing to your previous roaster (I also have DIY roaster and I am considering kaldi wide)?
I'm certainly still getting into the swing of things with the Kaldi Wide, but I have had some of the tastiest espresso ever in the last month.
That could simply be because I have read a lot more about roasting and with Artisan I can actually see the profiles as they unfold before my eyes, not necessarily because I'm now roasting on a Kaldi. That said the gas and airflow controls allow me the ability to actually follow a desired profile where before with my turbo oven top I was pretty much at the whim of "turn it on and let it go".
pcivic wrote: What would you say is max recomended batch size to still get good results for this roaster? Probably 300g is to much? How many grams batch do you usually do?
Actually I have done only 300g batches with it and no more and no less. That's what it's billed as as that's what I charge with :-). I was hoping to get a roaster that would do a good amount at a time. I like roasting, but as someone who goes through at least 600g of coffee myself in a week I don't want to be spending 2 hours every week roasting coffee.
pcivic wrote: Could you provide maybe some pictures of roasts with kaldi wide?
I last roasted Monday night, but here are a few pics of a couple of my roasts: Mexico Altura, PNG and Brazil Sweet Blue

pcivic wrote: And maybe experience after few weeks still happy with performance?

Thank you a lot for help! :)
I would say I am satisfied with my purchase although I am going to continue to tinker with it. As stated before the drop is a bit clumsy as you actually have to pick up the roaster to drop the beans. Due to poor planning on my part I accidentally melted the power cord of the motor by draping it across the flames once doing this. Luckily I have plenty of spare adaptors, and I now have it situated where that can't happen. Also, I need to make my thermocouple mounts more permanent, the bean temp one is floating a little bit. None of these problems are actually issues with the roaster but of my usage and modifications of it.
Felice wrote:Is the wide different than the kaldi that's been around for a bit (a year or so?) Also, I am very curious as to the difference with forced air vs not forced air.
The Kaldi and Kaldi Wide are slightly different. The Kaldi Wide has a better integrated trier / thermometer / charge funnel in my opinion. That's why I went with it. I'm not sure what the advertised capacity of the original Kaldi is.

As far as the forced air I'll admit I never once tried a roast in the Kaldi's "natural" state. I had the fan and fan controller before the roaster arrived so I modded it up before ever even turning it on.
http://bit.ly/29dgjDW
Il caffè è un piacere, se non è buono che piacere è?