@AndreG, did you use that copper tube to introduce the air further in the drum? Did you notice a difference?

Yes, my objective was to force the air to heat up and come out at 4 inches in the chamber.

On the first test, MET set at 275C after a 20 minutes warm up, I mesured the air temperature at 250F in the tube with zero fan. The tube air temperature drops to 100F with the fan set at full. I did a tear down to cleaned the roaster and the fan circuit shorted on restart. I am still waiting for the original parts.

The other tests will be to mesure ET, BT, Alt BT and MET and then, take the tube out and compare. Do the same with the Fire Blanket. I will post the results when the roaster is working again.

OldMatefromOZ has been very generous to explain to me a different technique with the drum cut-off modification (I ordered coffee from him to compare notes since he roasted more than 1500 batches on the Quest...). He uses a Fire Blanket (1 m. x 1m. folded in 3) over the roaster; a secondary effect seems to warm up the incoming air. I will certainly compare the temperatures readings.

REFERENCE:
Quest M3 model 2012-12 120V
Cut ½ inch thick drum + Painted Mat Black 1200F
Drum brought forward with less than 1mm between front wall and drum
Eric's thermocouples

I kept asking myself if it would be preferable to divert the cold air intake to the middle bottom of the roaster and warm it up by using a thick copper tube; somewhat replicate commercial roasters.

I can state that the copper tube does heat up the air proportionally to the amperage.
1. air intake 78F in the center of the end of the tube (middle of the roaster lying on the bottom) it's 123.6F at 4 amps
2. air intake 78F in the center of the end of the tube (middle of the roaster lying on the bottom) it's 187F at 10 amps

On the first roast, it accelerated by 30%. On my first try, ROR 19 in the drying phase, dropped at 211C, the roast lasted 9 minutes, dev 25,5%
That's quite fast for me and I am not sure I will pursue this.

Does anyone know the CFM min and max of the Quest fan?

Here they are Stephen:

Thanks Andre!!

That is a pretty wimpy air flow at a max of 21 CFM.

With the lag inherent in the small elements, I wouldn't want a stronger fan. I'd (already have) optimize the airflow's characteristics.

With holes in the drum around the back of the drum?

Primarily yeah. At least that way the air is being drawn thru properly.

I made the recommendation to Quest back when I made the mod and sent them pictures. Apparently they listened and are going to offer them that way from the factory now. I should get a royalty.

Did you put photos of that Mod in this Thread?