Newbie ROR Curve Question

Hello Aillio World… I have been home roasting on various machines from the teeny tiny i-Roast back in the day to an 800g DIY Fluidbed Roaster (which gave me some incredible roasts over the years). I recently upgraded to a Bullet to increase back-to-back roasting opportunities and have been getting varied results. Some cups are great others give me glimpses of greatness while still others are ok but flat. I typically roast dry process Ethiopians for my house because that’s what I love but picked up this fascinating Sumatra Dry Process Kerinci Pendekar.

I roasted up a couple of 750g batches today and thought it would be the perfect time to finally post this question as I have about 40 roasts on the Bullet under my belt and get a fairly consistent ROR curve to the one pictured here despite playing with charge temps, drum speeds, power and/or fan temps. When roasting on my FB I went primarily by sight and sound with a temp probe just to ensure that my heating element didn’t burn out on me :rofl: :joy: :sweat_smile: so ROR curves are fairly new to me and I’m having trouble determining if these are ok, terrible, good, bad or otherwise so any feedback would be dope.

Cheers! :coffee:

If the coffee is good the curves are exactly what they need to be. It’s always about the coffee. Trust your taste buds. So if it’s good, your only job is to keep doing it the same way. The graphs help with that.

I use IBTS (I-Temp) to manage my roast. On my roasts I expect a steadily curving I-Temp line toward the target. Near the end of the roast, bean temp (B-Temp) rises to a similar level as I-Temp so B-Temp & I-Temp kind of coincide at the end. That “convergence” starts happening a little before 1C. Any differences between I-Temp & B-Temp at the end of the roast probably have to do with calibration of the IR & temp probe sensors but that’s way beyond my pay grade.

I hate this part cuz talking about RoR always ends up sounding like a giant snow job. So maybe the best thing to say is that as long as RoR is above the zero-line, the related temp is rising. How smoothly the I-Temp/B-Temp rises toward the target is confirmed by I-RoR/B-RoR.

Trying to manage RoR directly is difficult at best but there are changes you can make to power, fan and drum which can be confirmed by changes in RoR. @bradm donated a lot of beans to the coffee gods when he first got his Bullet and has a better handle on Bullet operation than most around here. I tried directly managing RoR a few times but concluded I was making a difficult job harder. With a good combination of preheat & power settings, things work out in the end. That’s what you did and it sounds like you got some good coffee.



What Bruce said :slight_smile:

I don’t try to manage/chase the RoR curve actively either. The “F&F” I roast for likes it so it’s all that matters.

If you really want to get a bit more formal about it you can consider taking the eLearning course from Morten Munchow of CoffeeMind (search these forums for more info) or pick up Rob Hoos ebook on roasting. Some folks had taken Morten’s course and had good things to say - I didn’t do the course but I read Hoos’ book.

Happy roasting!

I appreciate both of your responses so thank you.

My entire roasting journey has always been about the coffee and what I like – I just feel like I’ve sort of started over now after moving from 10+ years on fluidbed roasters to trying to get my head/hands around dialing in a drum roaster to produce some of the same results in roasting deliciousness I achieved previously.

Honestly, I just wanted to make sure I wasn’t missing some huge element to getting accustomed to the bullet from more experienced drum roasters here on the forum so thanks for the feedback. My YT algorithm has flashed Morten’s class before and I have Hoos’ book in my Amazon cart. If I keep feeling like I’m struggling I’ll check those out.

Happy roasting!

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Yeah, the Bullet has it’s own set of learning hurdles not the least of which is the issue of hearing 1C & especially 2C as distinguished from the normal movement of beans inside the drum. If you have roasted with a system that includes software, e.g. something like the HotTop + Artisan s/w combo, the transition to the Bullet + RoasTime s/w is going to be relatively easy. The sounds (to the extent you can hear them OK!), the smells and the colors are all going to be the same. After that it’s a case of correlating those sensory inputs with the data displayed in the graph.

I see that you have roasted over a charcoal fire. Got a flashback to when I was on news group over 15 years ago. One of the roasters there swore by roasting in an iron skillet over an applewood fire. Kinda doubt he had any software to help him! :slight_smile:


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Thanks for the reply Bruce – interestingly enough I have a relatively easy time hearing FC on the bullet as compared to some other machines I’ve roasted on in the past. Before I moved from TN back to CA I was in process of installing an Arduino/TC4 w/ Artisan to monitor roast progress but ran out of time. I don’t have the same power available here as I did back East which is why I went with the Bullet. All that to say, I have no experience roasting with any kind of supplemental software.

Yeah, started on a charcoal fired, hand cranked, 1kg peanut roaster hahaha. It was a phenomenal introduction to rudimentary roasting but I prefer other methods nowadays. :nerd_face: