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Cymen wrote:

I joined recently after searching for some information online about building a roaster. For now, I opted to buy a Fresh Roast SR800 and did my first 5 roasts with that 5 days ago (170g each). I tried to wait a full 7 days to let the beans rest before trying them for espresso but I couldn't make it. So far, everything is drinkable. I did 4 roasts of an espresso blend (I bought 10 pounds of this to learn on) and another roast of a Peruvian decaf (SWP, bought 5 pounds to learn on). I didn't realize that decaf would roast different from regular and I took it farther and probably hotter than intended as it ended up with spots of oil after resting for a couple of days. However, the taste of this decaf is amazing in milk drinks. So far, I like the flavor of the regular espresso blend but curious to see how it changes after 7-14 days (if I can make it that long before using it up).

I live in a cold climate (5F/-15C this evening) and our kitchen fan does not vent outside so rigged up a ventilation system to blow out a window with some foam board in the window going to a 4" vent hose connected to a bilge blower pulling from a box with a steamer insert taped into one side sitting on top of a larger box. This contraption lets me ventilate the roaster and then I can take the smaller box with the steaming insert off of the top and turn it over and use it to cool the beans at the end of the roast. This is working great so far.

I'm here though because at some point I'd probably like to build a roaster. I'm still thinking all that through however I observed many builds using the Corning Bake-A-Round pyrex tube and I purchased one of those so I could hold it in my hands to get a sense of the size. I'm still thinking that through and enjoying reading the build threads.

Cymen wrote:

I need to roast some more with my Fresh Roast SR800 before I'm certain but I think I'd like a batch size range of 250-550g. It would be nice to go bigger however I want to keep the total size fairly portable. I also don't know yet if I'll have enough electricity for a fluid bed roaster so it might be better to go for a drum roaster. I found an inexpensive older used Kaldi for sale and I'm going to try to get that so I can see what it's like. Part of the reason I'd build is I want to go to remote locations where I might not be able to easily get a roaster mailed back and forth for repair. Being able to fix it myself and/or it being robustly built would a be a good thing. The FreshRoast is nice but it definitely does not feel robust and requires some care to avoid damaging it (glass roast chamber loosely attaches to base, plastic top chaff collector that can easily crack if dropped, etc).

allenb wrote:

Hey KK , what is your current method for heat control in your roaster? Are you able to set a power level that works for an entire roast or are you stepping the power up in a couple of steps and having to back it off at first crack?

renatoa wrote:

He means something as in the attached image.
A round cut to reveal completely the turbine, for full unobstructed airflow, and no chaff clogging, and leave only one inch ring for lamp protection.

A single level power roast, other than maximum power, I am afraid would be far from ideal.
You have attached a typical roast of mine, with power control steps generated by TC4ESP, based on some algorithm.
Somewhat unattended until approaching development.
The start power is 32%, used for preheat somewhere in the 180C ballpark, the maximum power (around DE) is about 66%, then lowered to 58% in the FC-development phase.
Probably a two steps approach could work. I mean start with 32%, TP around 1 minute, soak 1 minute, set to 48% at minute 2, then 64% at minute 3, and keep there to the end.
But a single level start to end...

I went back and reconsidered the mode of heat transfer with a turbo being to a large degree, radiant, which if left at full throttle will cause a much higher rate of rise when beans darken and would have the potential for 1st crack to wiz by.

jwmelvin wrote:



I just want to thank you for pointing this out.

I roast in a modified Behmor (Artisan controlling heat and fan), and this understanding of how radiant heat transfer changes when beans darken seems important to understanding why one has to cut the power so much towards the end of the roast. It may be a big part of why the Behmor can be difficult to make predictable, but I think that with emissivity in mind, I may get better results going forward.

Koffee Kosmo wrote:






That is exactly “as in the photo” of how I have cut away the defuser plate

KK

allenb wrote:

So all directly downward radiant energy is unimpeded so most IR is making it to the coffee ?