jammin wrote:While being able to nimbly guide a roast is a positive quality, knee jerk reactions nearly always lead to negative results.

A smooth application of heat is without question important.

Agreed and understood, however, some people like to drive boats and others like to drive sports cars. I'll always prefer the sports car and respect it enough to get the best out of it.

EddyQ wrote:Less thermal mass does not reduce lag.

When I refer to lag I'm referring to how long it takes for a given change in drum temperature.
Here's the science and math: Q = C x deltaT, where Q is heat, C is thermal mass, and deltaT is change in temperature.
The thermal mass, C =mc, where m is mass and c is specific heat. The specific heat is the same since both drums are steel and to make it simple let the 3mm thickness drum have a mass of 3 and the 4mm thin drumm have a mass of 4.
Now solve the heat equation for the change in temperature and you have deltaT = Q/C = Q/mc. So simply solving for the 2 cases:

3mm drum: deltaT = Q/3c
4mm drum: deltaT = Q/4c

Since 1/3 is greater than 1/4, it should be clear that the change in temperature for the 3mm drum is greater (faster) than the 4mm drum and therefore, the 4mm drum would lag the 3mm drum for a desired temperature change given the same heat rate to both drums.

Tonefish wrote:Agreed and understood, however, some people like to drive boats and others like to drive sports cars. I'll always prefer the sports car and respect it enough to get the best out of it.

Why don't you get a perforated drum then?

I understand the math and you are correct. For a given amount of heat, a thicker drum will take longer to get up to temperature.
However, when comparing a gas vs electric source of heat. The electric heat value (Q) may take 2 minutes longer to arrive at the drum relative to a gas. So different meaning of lag.

jammin wrote:Why don't you get a perforated drum then?

I think I like having a nice conductor between the flame and the bean. I don't know enough yet about what ratios of conduction/convection/radiation I'd prefer (or what the beans like). I gotta go one roaster at a time. The BC will be a big step up and learning curve from the Behmor and Fresh Roast I'm using now.

Did you get the perforated drum too?

No, but I had great results with one on my old Hottop

Is that a pressure gauge I see on the North roaster in the hopper chute/drum exhaust, or is that an ET gauge?

On My North tJ-67 1 Kg roaster .The dial on the Charge chutee is an Exhaust Temp Thermometer.
Steve