When to properly manipulate the use of Drum speed

Roasting on the Bullet R1
1

I bought my Bullet on August 2023, and had been roasting on it ever since. I understand the mechanism behind the power and fan speed but not quite understand the proper usage of drum speed. I started with 200c for preheating 454g, D7 at the beginning for the recommended setting, P7 and P2. Then after a while, I begin experimenting with various preheat depending on the various batch sizes. For 600g batch size, I found preheat 250C works best for me. I also start with P8, F2, D9. During yellowing, I lower to P6, F3, D9, when it’s near FC around 180c to 195c, I will raise to P7, F2, D9, to get to FC as soon as possible. Sometimes FC happened around 200C or 211C depending whether it is natural or washed. I found washed beans to reach FC much earlier around 195-200c whereas Natural would be around 211C… By the time, I’m ready to drop the beans, I will turn my heat down all the way to P3 or P2, and Fan all the way to F9 to have the development time. I would soak it for 1-2 minutes before dropping it to the cooling tray.
Anyway I never once change the drum speed throughout the roasting process. So when should I change the setting?
Lastly, I have not once roasted an awful batch of coffee, they all tasted great. But perhaps I could up my game a lot if I could fully understand when to change the drum speed wisely. All I know the drum speed change is needed if you want to have the bean to have contact with heat, so the the lower the drum speed, the more contact with the drum but would lead to scorching or facing. So I always crank up the drum speed to its maximum to avoid scorching. But I still see scorching on the beans especially they are natural processed despite with the drum speed set to D9 throughout.

Thanks!

2

I believe the drum speed is primarily useful for helping to prevent scorching. I generally set the drum speed to maximum and do not change it throughout a roast. You could change the drum speed to increase or decrease conductive heating of the beans. Slower speeds will generally result in more contact time with the beans, thus increasing conductive heating (and the chance of scorching). It may be more useful to play around with fan and power settings, rather than drum speed, to change the heat application.

3

Depends on what you’re trying to do. Most never reduce drum speed below D7-D9. I start at D4 and increase thru the first half to D8 as part of a ‘heat soak’ process I use…

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If you’re interested do a search here for ‘heat soak’ or for the guy who introduced it here, @quartzglen . Works for my purposes but is at odds with what nearly everyone here does.

Bruce