Thanks for the clarification Jim, You had me going for a while there.

It seems this baby will extend the magic for you for a good while, and I'm sure you already have many ideas waiting in the experimentation queue, so I'll try to put further suggestions on hold for now. Enjoy!

another_jim wrote:I've been reading a lot of blogs and articles on people using Probats and San Franciscans

If it's not too much trouble, can you share the links?

1
2
3
4

I'm sure there's more if you google beyond page 1.

Boot's profiles are from a sample drum? I always thought his articles were meant for big boy toys; which we shouldn't compare our tiny drums to, methinks.

I'm looking at everything written about solid ventilated drum roasters, regardless of size. So far, I learnt three things, all of which seem to apply to the M3 as well:

1. you can control the roast either with air or heat
2. you need to monitor environmental temperature, because it's very hard to get the heat and air adjustments right otherwise
3. the speed of roast is mostly determined by the drop in temperature.

A friend who runs a modified Gothot has said that it's important not to let the beans suck the heat from the drum down too much after drop by having too low a drum temp. or too large a batch. He was doing back to back roasts and not building the heat back up enough. He now starts restoring the heat while cooling the previous batch. Drum temp. management seems to be the key.

In my case it is the other way around. If I remember right, my temperature reads ~380F after a roast (after cooling). I would need to cool the roaster before the next batch if I were to use a 300F drop temperature. But sometimes I just dump the beans anyway because the new beans suck up a lot of the heat.

Boot's articles have helped me even with the HotTop. For example, his recommendations on bean density and allowing at least three minutes between first crack and ending the roast have improved my roast.

another_jim wrote:3. the speed of roast is mostly determined by the drop in temperature.

Jim,
Is "drop" here a verb or noun, e.g. the change (lowering) in temperature (and if so, what temperatures?), or the temperature at "drop-in" ?
-Ed

The bean temperature sensor at th time the beans are dropped in.

The M3 instructions, as far as I can tell, recommend a 160C to 175C drop-in (320F to 347F). This will give you about 10 to 12 minutes to get to the first crack. I've tried 190C to 200C drop-ins, which got me 8 to 9 minutes to the first crack. These times based on roughly the same heat and air settings after the drop-in.

The info I read on both larger drum and sample roasters seemed to indicate that the drop-in was more important for speed to the first crack than heat settings during the roast. I find this odd, but it seems that competent roasters have the drum at close to its maximum temperature throughout the roast, so the air temperatures at the roast's start may be the one big variable.