Roast runnaway's: Are all Bullets equal?

Hi guys, starting to experiment on my Bullet V1.

I’m trying to reproduce other peoples recipe for small batches (200-400gms) (The Bob Hoss for example) as I’d want to roast once a week and experiment roasting profile.

But i have a problem: when following other peoples recipe, my roast run away and burns.

Following exactly Bob recipe, (also cheated and putted more beans just in case (200g)) I got FC around 2min and a complete burnt roast around 6 min… how could Bob do a 9min roast with the exact same parameters yet extend it to 10-11 mins??

I suspect a couple of things (but i also feel stupid and like I’m missing something obvious):

  • dirty probe could read a lower temperature than real thus leading to higher preheat than expected?
  • different bean origin, size and humidity level… but to a 5min gap extent?
  • California dry air (16%) could lead to less cooling for the same airflow?
  • My Bullet just heats more than others?

In 4 tries, i couldn’t do a single low dose roast that was drinkable even with a good looking profile (see image below). The profile below looked a bit dark to my taste, smelled ok, yet tasted bad, and smelled burnt when ground.

Any help, tips and tricks would be suuuuuper apreciated!

First off welcome .I’m not a pro but you should change the blue line on your graph to IBTS temp. I use IBTS temp more than the bean probe temp. I don’t roast small batches (150 - 200 gm) . From what I’ve read on here it can be tricky. First crack should happen somewhere around 200 c so you should not be hitting it in 2 mins. Hearing first crack on the bullet can be hard. I would use a higher preheat and more power at the beginning as your roast seems to have stalled before the 7 min mark. I start at more power and reduce power through the roast.
Sorry I’ve just noticed you have a v1 and unless it’s been updated I don’t think you have an IBTS

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Thanks for the tips! With more power/higher preheat my beans gets from room temps to 180-190 in about 1min… i was kinda looking for the opposite answer haha.

And yes its a V1, so no IBTS, is it worth it to upgrade?

Are you sure you’re in celsius? I roast 1lb (454 gms) . Preheat to 250-260 c with an approx. 1 min p0 heat soak, then go to p8 or p9, dropping from there, and I get to yellow (approx 165 c ) in 3:45 to 4 mins. Once again I am not a pro but I think you will find most people on here use IBTS so if you’re trying to follow someone else’s roast that should be taken into account . I use IBTS temps for my roasts.


Hi @intelliespresso.bnCV and welcome.

I think @barry_p has good advice for you about Preheat and power settings. Basically the roast stalled at about 200°C. I’ve never roasted on a V1 Bullet but I suspect the IR sensor is of no use for managing the roast. So you will exclusively use Bean Temp & BT-RoR for roast management. In this roast things started out pretty much as expected (BT dipped and then reversed; BT-RoR rose above zero as BT hit the turning point from declining to rising). But there wasn’t enough heat to carry the roast to completion. Were the beans a very light color when you dropped them? I expect they were.

And to clarify, the original V1 Bullet has roasted a lot of very good coffee. You just need to learn the best way to manage your roasts on the V1 model. Most current posts on R.W are from V1.5 & V2 owners. So if you want info from V1 users, you will have to use the Search feature on Roast.World. You’ll be looking for posts from 2019 and earlier (the V1.5 Bullet deliveries started in Jan 2019- all activity was on the V1 Bullet in Jan 2019).

And this applies to searching for roast profiles from other users- you will see roast profiles similar to your own if you search for V1 roast profiles. Newer roast profiles will work fine if you just ignore the IBTS data and focus exclusively on BT/BT-RoR. With small batches there shouldn’t be an issue with differences in power levels at low P# settings caused by a Bullet with a V2 power board.


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Hi Bruce!

The beans were the opposite, full city + into Vienna, tasted burnt… I waited for the BT to get to around 205 but i should’ve pulled them way earlier. What I’m suspecting is that the BT may understate the actual bean temperature, causing my burnt roast and sudden runaways. I still don’t get how Bob Hoss proposed a recipe for 150g and 9 to 11min, and my bean were done at 6min

I didn’t get special beans or anything, the problem with Bob recipe and the rest of my small bactch (all brunt) seems to indicate something.

I’ll go and look if i can find other info in the old posts thank you!

Definitely in celcius!

And no, that would be impossible for me to preheat at 260, with a 200C preheat and P4-5 my beans were at 175C+ around 3min (turning point 184 ish at 4min).

I really don’t know what causes this huge difference in our roasters

If it helps you at all I checked my roasts and when my ibts is at first crack ,(about 199c on the Ethiopian
washed I have been roasting), my bean probe reads about 185c. Also , checking the graph you put on here , at two minutes your beans showed just over 150 degrees so I doubt you hit first crack that early.
The cracks can be very hard to hear on these machines.
Cheers Barry

Your preheat on the V1 is very different from the V1.5 or V2. You are preheating to 200C which is about 300C on the bullets with the IBTS. Your preheat temp is basically for a 800g to 1000g roast, so this is why it is going way too fast.
You will need to lower the preheating temp substantially or better yet, buy the upgrade for the IBTS.


Good lord i love you Jacob :brown_heart: : that was exactly the answer i was looking for!!

I achieved a decent roast with 190 preheat on the old bean probe: with your advice i’ll be good to at least roast for now! I’ll check if my board is compatible (plug and play) and look to upgrade to the IBTS!