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Roast Level Help Wanted
I've roasted about 12 batches of coffee in my Bread Machine / Heat Gun roaster I just built. Pretty standard mods (gun through the lid / vent in the back). Anyway, I got 5 lbs of Ethiopia Yurgacheffe beans and have been shooting for City to City+ roast. I've been trying to go just beyond 1st crack which occurred from (189 C - 209 C) according to my probe which is just below (3/4") the top of the bean mass when moving).

I realize it's hard to tell with a photo the level of the roast, but wanted to get some feedback. What do people think, is the City or beyond City?
TheHorse attached the following image:
Koffee Kosmo
Different beans from different continents will roast differently and display different colours
To my knowledge all roast level stages are judged after first crack.

You should judge your preferred roast level after it reaches first crack and the time in-between to the time the roast reaches second crack

Coffee beans roasted to any specific depth should also match ones preferred brew style as one may not be suited to another

I home roast and I like it. Designer of the KKTO
Roaster Build information
Blog -

Bezzera Strega, Mazzer Robur Grinder, Pullman Tamper Convex,
(KKTO) Turbo Oven Home Roaster.


TheHorse wrote:I realize it's hard to tell with a photo the level of the roast, but wanted to get some feedback. What do people think, is the City or beyond City?

Hello and Welcome,

Gotta love that HG/BM roasting!
I'm of the open top BM school of roasting and I'd like to recommend a few things you to speed you along your way. It's been many years ago that I did this, but it made a lasting impression.
Holding the heat gun in my hand, I started a pound of beans roasting.
I watched the temperature rise while noticing the change in the color. I scooped out about a half-ounce of beans when they first started to yellow, which was at about 270F on my probe. I put them onto a heat-proof table top and labelled them 270F and the time into the roast.
I continued to take out more beans at each 20 degree interval thereafter, placing them by the label for that temperature and time. Additionally, I pulled some beans at the usual landmarks: beginning of 1C, end of 1c, beginning of 2C and end of 2C.

That gave me a good starting calibration of time, temperature and color.
I felt proud and even took a picture of the array to refer to later on.
I did it other times at teaching demos. Attached is a cropped photo of one. So, I recommend that you open the top of your BM and give it a try, even once will be worthwhile, IMO. Take a picture and share it with us.

What I also noticed and still remember was the change in the aroma of the roast at each interval during the roast. There were several distinct changes. Surprisingly, it turned out that one of the most valuable landmarks was the change that occurred about 30 seconds or so before 2C. I was enjoying the nice roasty aroma when it quickly changed to a sharp, somewhat pungent smell that was quite harsh. I thought of how a nice campfire can change smell when someone drops some newspaper onto it.

I found this landmark to be a very reliable indicator that 2C was on its way. Now I could prepare to stop the roast right at the verge of 2C without having to wait for the first snaps, if that was what I was aiming for.
This indicator and the others still work for me with my RK Drum where I have no visual clues at all of how the roast is developing.

So, when I saw your picture I first remembered how my Yirgacheffe beans had typically looked before. But I immediately thought, I wonder how the roast smelled at that point? If I knew that, I believe I could tell you the answer.
Without that, they just look pretty dark and fairly evenly roasted (hurray BM). Closer to 2C than 1C, I'd guess.


David attached the following image:
Never tried the heat gun roasting with anything. I started with the Poppery II, and kept modifying that. Progressed from that to the Hearthware roasters, Gourmet, Precision, and iRoast2 and kept modifying those. Now, all three of those are still with me and the iRoast2, I what I use. At least the roast chamber, blower/heat chamber and body is. The rest of the internals have long been gone. Now it's PID and computer controlled but there is one thing I learned early using that old Poppery II, before this new PID and computer stuff came along. How to smell, see, and listen to a roast.

Every roast, you need to be smelling that smoke from start to finish while looking at the bean color because during different phases the smell is going to change, and you need to learn the color of that bean during those changes. I mean, close your eyes for a few and concentrate on just what you are smelling, then look at the beans I keep a 50W Halogen spot light near me so I can see the actual color and not some shadowed color. Then you pay attention to just how the beans are changing during the whole process. When you learn this, then you will be able to learn how to roast beans. As mentioned, I have the PID and computer I can set up any roast profile I want and repeat it every time, but the only way that computer is going to know how to roast those beans is by what I put into it on how I want to roast them, and there are far too many variables for someone to be able to tell you how to do that.

Now the technical side I'm still learning big time, like if you want to change the roast to accent a certain part of the flavor profile, just where and how to do that, I'm a green horn at that part and that's where all the fancy electronics help me.

I look at roasting like shooting. I'm also a very good shot with a rifle and have some very accurate rifles, and reload my own bullets for the most accuracy. One of the questions that gets asked the most is someone ask what's the best load they can shoot in their rifle. All I can say is, don't know. I know what shoots best in mine, but no two barrels are the same, so no load is going to shoot the same in different rifles. Trying to use someone else's roast data in a different roaster would have about the same affect, no way is it likely going to come out the same.
The kind of info I'm always looking at is, if they speed it up here, or slow it down there, will cause a certain change. That's useful information.

Dang, I got long winded, just to say, learn now to use your senses early and the rest will come.
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