Perforated Drum Vs Solid Drum

[edtbjon]

Hi and welcome!
On the solid vs. perf. drum debate... As long as you are learning to operate the roaster, it really doesn't matter. It takes a long time to learn the roaster in one configuration and whatever you change (J-pipe to T-pipe, Exhaust bowl to cyclone, drums etc.) you have to adapt and tune in to that particular config. With all the collected knowledge that you find in this forum, the path to getting decent roasts from your roaster in any configuration is way shorter than what it was a couple of years ago, when the forum started up.
The basic coffee roasting principes apply to any setup, but the way you handle the controls on the two setups differ, mostly due to different airflow and different drum mass. The results from solid and perf. drum respectively are comparable with subtle differences (i.e. there is probably nothing that can not be compensated for). Please do note that a roast profile from a solid drum setup doesn't neccessarily (sp?) directly translate into a good roast profile for a perf. drum machine. It could be a good starting point from which you compensate and tweak though.
The best advice is probably to stick with one setup and stay with it until you feel really confident with it. You cannot fix any roasting problems with changing drums. The only way to fix a roasting problem is to change the control profile (i.e. how you handle the gas and airflow respectively), resulting in a roast profile.

[Brent]

Thank you so edtbjon. I appreciate your input

[Brent]

 I've been doing some reading on the subject of perforated drums vs solid.  Not surprisingly,  perforated drums allow for more convective heating than solid drums.

 I have to wonder, because there is more heating of the beans with hot air, how much that affects the taste profile. Fluid bed roasting, as opposed to drum roasting seems to give a slightly different flavor profile with the same bean.  What I remember from my air roasting days is, fluid bed seems to highlight acidity more as well as floral fragrance and those higher notes and aromas (for lack of a better term) more than drum roasting. How much of that is actually down to the different method and how much is due to shorter roasting time and different profile, I'm not 100% sure.  Though some fluid bed roasters have enough profile control so that you could get a roast time similar to what you get with a drum roaster and vis versa with smaller drum roasters. I did stretch out some air roasts to around 9 mins to see how much that changed flavors and I recall that Istill noticed the attributes I mentioned above.

So I'm curious if a perforated drum, due to more convection, might produce roasts that lie somewhere in between a solid drum and fluid bed as far as what flavors end up in the cup.
I suppose one would have to roast the same coffee, with similar profiles, in the two different drums to really do a true comparison? That would probably be a pita to do.

I'd be curious to hear opinions and would be interested to know if anyone has used the different drums to roast the same beans with similar profiles

[edtbjon]

The subtle differences you describe in comparing fluid bed vs. drum roasting is what others have reported too when comparing Huky setups. I.e. a slightly more highlighted acidity etc with the perforated drum.
As noone really have had two machines setup parallell long enough to really learn them both to be able to give them a valid comparison, it's really hard to say how much they differ. But nothing of this really matters before you are in full control of the roaster, being able to both replicate roast profiles, hitting the milestones well within say 10 seconds, as well as adjusting a profile in small or larger steps too. Now, don't forget to really enjoy all the good coffee that you've roasted during that trip.

[hankua]

Is the perforated drum Huky better for light/Nortic profiles?

For me the debate between perforated and solid Huky drums boils down to which one is better for what? In theory the perforated drum should be better for shorter Nortic style roasting while the solid drum should be better for development type roasting.

Why is that? The perforated drum's convection/heat transfer should able to penetrate the inner bean faster than solid drum. Underdevelopment is the enemy of Nortic style profiles; incomplete heat transfer.

Solid drum by design has more surface area for conduction, and operator can limit convection by reducing fan speed. Is the solid drum better for development/full city roasts? That's my question....

We can never replicate a Probat or other commercial machine's abilities because they can store an enormous quantities of heat compared to the lightweight thin Huky. That's why you hear people comment my "xyz" roasts better than the old Huky; it's better cause it's bigger. When you load up a big roaster with heat, room temperature greens have way more heat exposure from the drum.

With a Huky one has to approach the end game differently, using the tools/levers available; even if they contradict Rao, Hoos, etc.