A friend wants to roast at home and I agreed to share the cost of a roaster to enjoy use of it. But we are in the research phase of cooperative roasting. Most likely a drum roaster of some type is on the near horizon, but our first test will be on a friend's Artisan 6 fluid bed. IF we can control that roast to our liking we might use it for larger batches. Plus it will be a pleasure to learn along the Roastroad with him.

So the question is, what charge temp is appropriate for a 3 lb charge, intending to reach end of dry phase around 5:30 close to 25% development before finish at 415F?

Is that a fair question for someone wanting to test a large fluid bed or is there something about the roaster itself which determines heat transfer making the question useless?

charge temp is only relevant to roaster thermal mass and roaster power. No one size fits all answer.

Chert wrote:Our first test will be on a friend's Artisan 6 fluid bed.

On a continuum which runs browning beans -> artisanal, craft roasting, an Artisan 6 locates you a lot closer to browning than to craft.

So the question is, what charge temp is appropriate for a 3 lb charge...

Because the roaster doesn't have any thermal mass where it counts and is completely open when beans are added, the concept of "charge temperature" is meaningless.

In terms of the Artsian 6, what you're really asking is what wattage do you want to use to start. In the interests of completeness, I don't know.

... intending to reach end of dry phase around 5:30 close to 25% development before finish at 415F?

What are you trying to ask? What does "close to 25% development before finish" mean?

Is that a fair question for someone wanting to test a large fluid bed...

Fair question? Don't know. But it presents another opportunity to say the Artisan 6 isn't designed for sophisticated profiling. Not that it's impossible, but it seems to me that using one for the purpose way is like trying to teach a pig to sing.

Is there something about the roaster itself which determines heat transfer making the question useless?

Obviously fluid beds contribute a higher proportion of energy transfer by convection and a lower proportion by conduction than drum roasters do. How much of a difference that makes in terms of the roast master's ability to profile is up for debate.

Rich

What are you trying to ask? What does "close to 25% development before finish" mean

I was trying to succinctly state the intent that 25% of the time of the roast would be between start of first crack to dumping or quenching the roast.

Thanks for the input. It will probably be difficult to translate between two very different forms of roasting, I'll post back something about what degree of insight I gather.

I have had coffee from one Sivetz roaster and I have not found it a match to the pros on Drum roasters. Hint, hint: someone should make a list of roasters who sell their beans from a fluid roaster. I'd like to try them and share with my friend who is using the Artisan 6.

Walla Walla Roastery started about 12 year ago with a 5Kg Sivetz. They might still use it.

Try the following:

Charge temp 230 C or 445 F
ET 260C or 500F

You may need to increase ET in order to get the roast within the 7.5 mins interval

EDIT: just noticed you are aiming for a 415F finish, you should get there within 7.5 mins with above settings

Thanks for the suggestion Gor. But what I want to achieve with the roast session is 5 1/2 minutes to dry phase end, ramp 3-4 minutes and from there to drop at 213C /415F, total roast time 12-13 min.

Chert wrote:But what I want to achieve with the roast session is 5 1/2 minutes to dry phase end, ramp 3-4 minutes and from there to drop at 213C /415F, total roast time 12-13 min.

Assuming 1stCs at ~390F, a Development ratio of 20% will be very tough to get with a 415F (barely C) drop.

You've got very definite and very interesting ideas in terms of both roaster and profile, but they may not be achievable as they stand. You'll learn a lot of valuable lessons, though.

Rich

What are the specs on the Artisan 6? What is the rating on the elements and where are the temp probes located?

I ask this because I was only taking a guess at what you might want to start with in terms of temps. My air roaster and yours are totally different in the way the heat is applied and controlled.

I can vary the ET on mine via PID and the max is set at 380C. It is powered by a 3phase 32amp 415 volt supply. The elements are rated at 18Kw with a 3.5Kw side channel blower to supply the Airstream. It has a large thermal mass and takes 15 min at startup to get to temp. It will roast 12hrs a day 24/7 and to give it some perspective, I was roasting the other day on a 40C day with a number of slight adjustments to settings.

Obviously I can't compare the Artisan to the one I've got, but I am always interested in how other roasting machines behave. This forum on HB is totally informative in that respect and I love reading it!

I have roasted on a drum before, but it was a 120kg unit. A totally different kettle of fish.

Supposedly the heating elements are the same ones that were used in the Sivetz 8# roaster. I believe there are 2 5500 watt elements which can produce over 10K watts...more than enough to roast 6# of coffee. Ken says it can roast 8# in 12 minutes now that the cooling tray can accommodate that much.

Mine just arrived and I will be starting to play with it next week. I'm in the middle of converting my garage to a 4-season shop and just finished hooking up all the electric including a 60A line for the roaster.

There is a PID that controls the ET. and that reading is taken before the air enters the roasting chamber. You adjust it by turning the wattage dial. Ken suggests starting around 5K watts with a 6# charge for a slowish 12 minute roast. So you should be lower for 3#. Unlike the small Sivitz machines, where charge weight was critical since air flow and temp were not readily adjustable, the Artisan 6 has completely adjustable air flow and heat so it can roast anywhere from 150g to 8#. That's pretty cool.

The BT probe is immersed in the bean bed and should yield a very accurate reading of bean temperature. I'm not sure how I will modify mine to be able to use Artisan software to track roasts yet. But another nice feature of a fluid bed machine is the ability to readily view the beans and what is happening. If you're charge is getting through the dry phase too quickly, simply reduce the heat next time until you get it where you want it. That might require tweaking the temp up after the dry to achieve the ROR desired. Unlike a drum roaster, a feature of this machine is that temperature is immediately adjustable at any point of the roast.

It is a manual roaster and constant attendance is "recommended", I'm sure it will be very possible to adjust the wattage at each stage of the roast to create any profile desired. Of course Michael Sivitz would scoff at this claiming profiling was a waste of time. Time of roast and final bean temp were all that mattered to him. The beauty of his machines were that results were very uniform and repeatable since the beans are in constant motion and bean temp is measured so accurately.


Here's mine awaiting install. I built a little platform on wheels s I can move it around as I work on the shop.