Recently replaced the "P" panel with a "B" panel and added environment and bean mass temperature probes.
Pictures and write-up at the blog link below.
Very cool! I have the P, and sometimes wonder whether a B would not be better. I have asked Michael at HotTop to set up a forum on their site so HT users can share their profiles for different beans. The bean mass thermo seems to be very valuable, but why did you install another environmental thermo? Is the installed thermo not accurate enough, or do you want the USB from your datalogger?
The standard thermocouple is coupled too closely to the rear wall temperature, so it varies with outside air temperature and whether the roaster is cold or hot. It tracks well with the profile, so it serves its purpose for the stock model, but it is not an accurate measure of the environmental temperature driving the beans.
I had a little trouble this morning--was getting some goofy things with the environmental probe--its temperature went lower than the bean temp with the heater on (and bean temperature rising after 1st crack was concluded). I knew it was off. Pulled the TC wire out from the tube a bit on both probes, and the next three roasts tracked perfectly.
Here's what makes having temperature and full control great:
First two roasts were intended to be FC/FC+ with a Triple-pick Sumatra. Both went between 4-5 minutes from first crack start to end of roast, with end bean temp around 440. Last roast was an Ethiopian Natural Sidamo, which I pulled at 420, but with the control and temperature monitoring, I still had over 4 minutes from start of first to end of roast, without stalling.
"Vincent! We happy?"
"Yeah, we happy."
I'll have a few profiles posted later today.