I have a roasting problem with ground weight in basket after distribution, when leveled to the rim:

while using modified poppers as roasters, for a couple of years, I was happy using with my Bezzera Magica (HX E61) the most convenient - for me - method of distribution:
leaving the grounds as fluffy as possible, NSEW leveling to the rim (with kind of a silicone straight knife), and with my usual beans I had quite consistently, around 16.2g, maybe 16.5g; for a double basket of a nominal 14g...

since end July, I am using a DIY roaster, based on a heat gun with 'continuous' temp control, and an external air pump, also voltage controlled, all monitored in Artisan;
well, the grounded beans roasted with the new heat gun/air pump roaster, weights - in apparent similar conditions and in the same basket - much more: over 17.5g, to 18g!
and this, with the same green beans (Yirga, Malawi, Salvador etc.), as the ones roasted on the poppers,
roasted in about the same time, 9 min, to City plus, with the same visual characteristics,
with the same grinder, at about the same setting, fluffy as possible into the basket leveled to the rim;

I was tempted to consider the grinder, a rather modest one, Bezzera BB005 (48mm conical), but recently I tested it by grinding (not brewing:) with ancient roasted coffee bought from supermarket (some Costa RIca Tarrazu, or the remains of...);
but, the levelled to the rim basket, hold 15.5 - 16 g! like those with the old popper!

I am not considering the final result in cup (good or excellent in both cases), nor the difficulties of distributing a "downdosed" grind (as 16-16.2 g of grind are now below the rim);
my concern is about the possible errors in the way I'm manipulating the roasting process now;
what would be some possible causes for getting such a different roast bean (more dense?) on different roasters, otherwise in rather similar roasts?
where should I look for them in the rosting process?

it's hard for me to believe that working with a larger batch (250-300g vs. 65-75g) only, would get such a result;

well, there is one thing I've noticed as a difference: first crack starts at a moment when the beans seems to be too roasted and clean (not that 'shedding' look) for the phase - they've reached almost the final color of City - City+

with the popper, I used to 'charge' at about 80C (175F) and soon after, at 149-150C (300F) I dried for 2:30-3 min; then ramp and in 3-4 min at 200-203C (394F) entering first crack;
now I charge at 150C (~300F), the recovery from TP to 150C (~300F) again (end drying) is rather slow;
is this drum roaster' profile appropiate for fluid bed method?

thank you for any hint!

another_jim wrote:Have you changed grind settings, shot timing, etc?

Typically drum roasts produce more fines at a given grind setting than air roasts....

How come this is the first time I've ever heard this?
I wonder where in the typical roast curves this phenomenon occurs.

another_jim wrote:Have you changed grind settings, shot timing, etc?.

yes, in order to get the same flow; but of a very few significance I would say, as the main difference and my qustion is about the grind resulted from the old popper roaster, and the one from the new heat gun / air pump one;

another_jim wrote:Typically drum roasts produce more fines at a given grind setting than air roasts. ...
But if on yor set up, you needed to grind finer, the mystery would be explained.

thank you, Jim;
so these would hold to be true:
when using the same grinder at the same setting, the new heat-gun/air-pump roaster (with its larger batches and different temp distributions) produce more fines than the old tiny mod popper; the roasts being dropped at approximately the same stage;

endlesscycles wrote:...I wonder where in the typical roast curves this phenomenon occurs.

better put, that would be also my question