Help Please: Getting Tipping on 1kg Mill City Roaster

Dronizm5

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May 1, 2021
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Hello everyone,

looking for some advice on a mill city 1kg. I keep getting tipping with my roasts. I am a novice and looking for some advice on what to do. I charge based on my PID. Should I be charging based on my ET or BT probes? They both read higher than the PID on this roaster. I have tried charging between 380 and 400 but can’t seem to figure this out. I am roasting a Brazil natural process from genuine origin. If there is any advice you could offer it would be greatly appreciated.
 

PinkRose

Super Moderator
Staff member
Feb 28, 2008
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Near Philadelphia, PA
I had no clue what tipping was, and I had to "Google it." You learn something new every day.

Tipping happens when the beans experience any temperature too high for the bean's heat-transfer coefficient. When there is so much energy (heat) around a specific part of the bean that the bean cannot absorb/conduct/disperse the energy fast enough. The only choice left is to burn in that particular area.
 
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Dronizm5

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May 1, 2021
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Airflow low in beginning during soak then I turn it up at turning point and before first crack. I have tried having a good amount of airflow during soak and I still was getting tipping. Thought my drum speed was too fast so I slowed it down. It seems to have gotten a bit better and I am noticing it on less beans. I charge with my PID temp not my BT or ET. I may start charging based on that because they read 30-40 degrees hotter than PID.
 

Musicphan

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May 11, 2014
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Kansas City
What temp are you dropping? What is the PID/ET/BT temps when you drop? It sounds like you have most of the fundamentals down... while you figure this out try and limit the number of changes.
 
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Dronizm5

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What temp are you dropping? What is the PID/ET/BT temps when you drop? It sounds like you have most of the fundamentals down... while you figure this out try and limit the number of changes.

420-430 drop temps. PID charge is at 380-400F BT/ET probes reading any where from +30-40F
 

Musicphan

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May 11, 2014
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Kansas City
420-430 drop temps. PID charge is at 380-400F BT/ET probes reading any where from +30-40F

I'm sorry but this doesn't make sense to me. What is the PID charge measuring? Is it a 3rd thermocouple? If I understand, you are charging via the
380-400 PID charge measurement. If it's at 400F - what are the BT & ET thermocouple readings? Are they reading 430-440? If you are charging your roaster at too hot. Drop the BT temp down to around 400F and give that a shot. I run a 12K USRC and I typically start my first loads around 400... keep in mind the Brazil naturals are pretty soft beans - especially since your roasting a natural. You have a lot of sugars on those coffees and need to roast them less aggressively.
 
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Dronizm5

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The PID probe is reading drum temperate. It is to the left of my drum if you were looking at it from the front. The BT is on my door and ET is top right of drum. My temps vary 30-40 degrees. I will try using the ET/BT for charging and see how it goes
 
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