Gary, I don't know if this latest experiment challenges your previous generalization because you're testing very distinct and different coffees from different places, one natural and one washed

In Rob's case, I don't think so. He is concerned with inlet temperature not being excessive and manages that with high airflow to distribute heat through the roasting chamber. In my fluid bed roaster, I don't do a maximum load so that the air will freely circulate through the bean mass. With my 1 Kg...

You might also set the air flow at maximum so that roasting temperature is spread through the roasting chamber. That's what I've done with a North TJ-067 1 Kg propane roaster. I start with the highest power setting when the beans are most able to absorb heat and bring it back throughout the roast. I...

Rob Hoos sets airflow at 100% from the outset on his 3Kg USRC roaster. At least that's how I understood that point in his paper on tipping. I do that now on my 1Kg propane drum roaster and get very good results, applying consistent heat without tipping. It helped to get used to a fluid bed sample ro...

It's hard to tell whether that's rust or brass showing through where the chrome was removed by intensive descaling. With the siphon tube, you could try seeing whether Evaporust removes that coating. If not, it's copper. But it looks rough rather than shiny. I think someone mentioned earlier in the t...

Agreed. I've never had a siphon tube look roughly red like that. They're either black with oxidation or pink, smooth copper

I can take a photo and measurements for 3D modeling, but we should also compare my trier to Eddie's. A spare part of a North or Mill City roaster could be hard to obtain without a special order from the manufacturer. An alternative is to find a pipe that fits the insert. BTW it really helps to have ...

Do you have a rusted siphon tube? Also, BTW, if you do lots of descaling, that doesn't necessarily clean coffee oils in tight and remote places

Me too, if you'd like. I'm across the river from you and have a TJ-067

Since no one has asked this yet, how do your roasts taste? Are you happy with your results? As far as BT ROR goes at the very start of the roast, that's when the beans are full of moisture and there are few chemical reactions happening. You're essentially building pressure inside the bean and heatin...