Bruce: I believe a cold roaster drum always needs pre-roast tempering. When I turn on my cold bullet, it takes about 15 min. to get to “charge,” at approx 330f. Not enough for me. I extend my preheat cycle with a partial roast cycle using approx. 12 oz. of discard green coffee (easy to buy at most local roasters for about $1-1.50 per lb.) that I take just past first crack/385 degrees.
After that partial roast, my bullet will automatically reach a preheat bean temp reading near 370f and a drum temp reading at approx 400 before it gives a “charge” notification. That’s what I consider the perfect drum pre-heat tempering for the bullet. At this point, I’m ready for my first production roast.
My bullet will then automatically announce a “charge” at 370 degrees, which will be consistent for all subsequent production roasts.
SO: At “charge,” I add cold beans (450-600 grams). I reduce my heat to power 1 and, after 15 seconds, reduce drum speed to 3. For approx. 30 seconds, the bean temperature reading drops steadily, as beans “soak-in” the ambient internal drum heat, evening out at approx. 230f between 50-to-60 seconds. At that even-out point, I manually “charge” my roast by turning temp up to 8-9.
SOAKING has always been a bit controversial. I’ve sat through many roasters’ forums at SCA conventions where roasters have debated the value of soaking. I believe the point where soaked beans and external drum are the same temperature is the ideal starting point point for adding a full-roast charge.
Take this for what it’s worth. I’m not out to prove anything. If you try a soak, let your post-roast cupping session be your guide.
P.S. As I wrote earlier, I’ve never done a full-capacity roast. I’m happy sticking with roasts between 450-600 grams. I have no data for you re: full capacity bullet roasts.