How to duplicate a good roast?

Roasting on the Bullet R1
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Is there any way to replicate a roast by doubling its size? I have roasted 400g and I really liked it. Now I want to roast 800g of the same coffee. Is there any reference or idea on how to adjust this new quantity so that the ROR curve is as similar as possible?

Also, could you provide me with a guide for roasting 800g? I don’t know where to start. Preheat and fire settings?

Thank you very much for your help.

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To not waste beans I will work up a 450g profile for a new coffee, then step it up to 820g for time efficiency when „production“ roasting.

Translating the smaller roast to large is an educated guess followed by some trial and error. The Bullet manual provides some guidelines for batch sizes. These can be good to help interpolate and make a good guess at where to start on the larger batch. Was it a a high or low preheat on the small, transfer this to the lrger batch site range. Same for power application. Same for power application. I’ll usually up the drum speed a step to accommodate the larger batch.

Overlay the smaller profile, apply your interpolations and give it a test roast. I’ve had a lot of success on first attempts, often been able to make tweaks to nail it on a second attempt.

Occasionally I’ve had a bean that just doesn’t make the larger batch transition. Seems like the roaster just maybe doesn’t have enough power to replicate at the larger batch size. In this case I’ve had luck scaling back slightly and doing a 650g batch size.

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  1. Increase the preheat time: Since you’ll be roasting a larger batch, it will take longer for the drum and beans to heat up. Increase the preheat time by 1-2 minutes to ensure that the drum and beans are evenly heated before the roast starts.
  2. Adjust the heat application: With a larger batch, it may be necessary to apply more heat during the roast to maintain the same rate of rise as the smaller batch. Start with a slightly higher heat setting and adjust as necessary to maintain a similar ROR curve.
  3. Extend the roast time: It may take longer to reach the desired roast level with a larger batch, so be prepared to extend the roast time by a few minutes if necessary.
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Hello everyone.

I’m starting to double the size of my roasts (from 400 g to 800 g) and I’m having big problems with underdevelopment.

If you can see my latest roasts from Guatemala and Peru, the weight loss is approximately 12%, which seems ideal and correct to me, but even so, I’m unable to grind these beans (Niche Zero gets stuck) and it’s obvious that I should have roasted them for longer (it’s not as dark as I wanted it to be).

My main problem is that I hear the FC too early, around 7-8 minutes, even below 195ºC, so I get scared and end the roast too early.

My question is as follows: I was starting the preheating at 285ºC, if I increase the preheating to 295ºC, I’m afraid the bean will roast too quickly on the outside. If I lower the preheating to 275ºC, I’m afraid I won’t be able to generate enough heat and the bean will remain underdeveloped.

What basic recommendations should I follow to extend the roast to 10-12 minutes to delay the FC and avoid burning the beans?

Thank you in advance.

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285C for 800g seems reasonable.

What does your power profile look like throughout the roast?

Are you using an R2 Bullet or earlier? 220V or 110V?