PID tuning for popcorn roaster

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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PacMan
Posts: 127
Joined: 13 years ago

#1: Post by PacMan »

Just finished putting together my popcorn roaster with a spare PID being used for the temperature control. I have the TC located where the hot air will be entering the roasting chamber. Just fiddling around with the setup I noticed that the temperature usually overshoots the set temp on the PID. I figure an autotune is in order. My question is, what temperature should I set the PID to for autotuning or does it not matter? Also, with beans in the chamber to simulate an actual roast environment or would an empty chamber work ok? Thanks for the help.

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allon
Posts: 1639
Joined: 13 years ago

#2: Post by allon »

IIRC, I auto tuned mine while roasting around 300 degrees or so.
I wanted the beans to be in a relatively linear phase. Around 1st crack it will be nonlinear and there are various sivetz "bumps" that can throw it off.
I also placed my thermocouple to the side of the air stream, in the bean mass.
What kind of controller do you have? I assume it can ramp/soak with a number of program steps?

(My machine is an iroast2 gutted and PID'd but is essentially the same as a popper for comparison purposes)
LMWDP #331

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PacMan (original poster)
Posts: 127
Joined: 13 years ago

#3: Post by PacMan (original poster) »

Thanks for the response. I'm using a basic auber PID that I had left over from a previous project, no ramp soak. I know this is suboptimal but since it was just sitting in my basement I figured I'd give it a try. I'll try a few roasts with it and then splurge on a ramp/soak PID later if I need to.

I'll follow your suggestions and try the auto tune around 300 and see how it works out. My probe isn't in the bean mass though so maybe I'll try it without beans. No venting setup yet so this way I can do it indoors.