New roaster - what am I doing wrong? [roast pictures]

For my first several years roasting, I was using the FreshRoast SR 800. I got reasonably good at it, and was able to deliver a consistent roast. Since moving to the Bullet, I am really struggling. I have read and watched everything I can find, but still cannot get the same roast quality, which I realize is a me problem. Recently, I roasted some Bali Blue Moon beans and they came out looking like this.

Here is the roast. What did I do wrong?

First and foremost, welcome to the forums!

With these beans and this roast profile specifically, a couple things jump out at me. While I can give some suggestions, you’ll need to experiment more to find the true root cause.

But that being said, here are my thoughts:

  1. The Indonesian roasts I’ve run (Sumatra, Sulawesi, and Bali) have all thrived at your darker roast levels. You dropped out your beans at about 209C – I would personally try running these beans darker.

  2. It could be the image quality, but the center of your beans appear fairly light – am I seeing this correctly? If so, I’m thinking you may have roasted a bit too hot, causing the outsides to get dark but the inside to be a little too under-roasted. Beans like these are okay to take some more intense heat off-the-rip, but you’ll want to allow for a more controlled (and more prolonged) duration inside your caramelization and development phases.

  3. Don’t be afraid to experiment with your drum and fan speeds to achieve better control of RoR inside different phases!

I hope this helps without overloading you with suggestions!

When I roast 500G my preheat is much higher, 455F to 482F which will propel your roast into a robust first crack.

I agree with @larryaknigge, I normally pre-heat even higher to 265 - 270 C for 500 grams and usually stick to 265 C for 1# (454 grams). Something to look at. I go up to 285 C pre-heat with my 700 gram batches. I usually have the fan set at 3 from the start.

How do they taste? Your profile looks pretty good otherwise.

Yep, try dropping around 220C for those beans and see how you like it. As someone mentioned, your roast curve looks pretty good. Also agree that a preheat of 270 +/- may be ideal

^^^ this

I would first get the preheat higher (205C is just too low for a 500g batch).

Then work on dialing in the degree of roast.

Start with inexpensive beans, and change one variable at a time until you’re getting results that you like. Keep the roast plan simple and focus on cup flavor and not appearance or pretty curves.

Have a look at How to Begin Roasting Great Coffee on the Bullet R1 V2 | by Aillio | Medium to get some good rules of thumb for the Bullet.