Talked with a machinist today, and have yet to send drawings of what I want, but to manufacture the drum, he was thinking that I am in the thousands of dollars… might be why there are no drums built the way I am envisioning… Not quite back to square one, and I’m not going to completely rule out having this done, but I think that there are cheaper ways to prototype this before spending “thousands”…
Archive for the 'roaster' Category
Been doing quite a bit of research and evaluation around the application of stainless steel as the contact surface.
The Pros
It doesn’t react with food. so the oils from the coffee can be wiped off the surface, leaving you with a drum that will not impart any flavor to the batch. It would be somewhat insulating to the roast environment… which would, in theory, make the roast environment more stable… It would be durable – not that the beans are that hard on the surface, but I think it may keep the drum from warping over time – a condition that seems to be a bit of a problem with older roasters—at least ones that are not well taken care of.
The Cons
I’m a bit worried that there needs to be an easy way to clean the surface of the drum, probably when it is still warm to remove all the oils from the surface of the drum. It makes sense to me that if they are not being absorbed into the metal (as they are when you have/season a steel drum) that they will turn rancid, and impart off flavors to the roast.—this may really just need to happen after each roast session though.
It’s a lot more expensive to use SS than mild steel.
It is a bit harder to work with, though not that bad, really.
It’s got such a low coefficient of thermal conductivity. It could easily have a tendency to get hot spots if not very very evenly heated.
—Not sure if this is a + or -, but it should be a good insulator of the heat inside the drum, making the process (slightly) more efficient.
Poor thermal characteristics would probably make the roasting environment less responsive to changes made at the flame.
Thoughts
Would likely be best if it were a very thin layer of SS – likely 1/64″. (looks like it’ll be about 1/16th thick).
In the end – what I am after is a drum that will have an high balance between responsiveness, even heat distribution thoughout the roast chamber, and with the added benefit of a non-reactive / durable surface… That leads to stainless, for the interior of the drum—as thin as I can manage—and a thicker outer layer of a good heat conductor to create even heat distribution. Wow, I just re-invented the All-Clad cookware. (!). Intuitively, I think that the pros outweigh the cons, with the caveat that the SS needs to be as thin as possible to minimize it’s thermal drawbacks.
I know that there are people who have toyed with this before, <link to rg post>. The thing is, that it is not readily available, and as far as I can tell, maybe only Smart Roasters (Kestrel, etc) have been the only ones to work out the specifics of this. I have heard of one SS sample roaster, but can’t find any information on it.
So, this leaves the outer material…
from what I can tell, I have two real choices: Copper or Aluminum. Copper being the obvious better choice – it is a better conductor of heat than aluminum, and undergoes less expansion than aluminum, by about 50%. Which makes it closer to steel (I don’t think that I will be able to get a clad piece long enough to make the drum—though I am considering piecing it together from several clad pots). However, I would rather go to something that could conceivably be manufactured, and that would pretty much exclude using a clad sauce pan… (but never say never).
But you can’t weld it—not that this is really a deterrent though, but I haven’t located copper tubing large enough yet—and I’m a little afraid of what the cost is going to be… We’ll see.
This is gonna be personal.First, the explanation. Deft. It is skill with the hands… It is only and nothing more than manual labor. For sure, everyone that touches and somehow affects the quality of coffee is engaged with it in a personal way. That’s it. My part in this is that I am a roaster of coffee—the next to last step in its preparation before consumption. I find coffee to be everything and more than what helps me wake up in the am… it is food. And like every other food, it can be bland and nothing more than sustenance, or it can transcend the ordinary, the merely not-dead and become an integral part of the complexity and richness of life. A symbol… no. More than a symbol. An actual push towards being able to wake up each day and, with bleary eyes and mind, make determined steps toward declaring this is a day I will live the way I intend. Go always toward our dreams.
If our lives have ever come to a point where all we are looking to do is wake up in the morning and get on with our day, all we are doing is being a single tooth in one of an uncountable number of cogs, twittering and twirling through our lives on some other body’s path. But what fun is that? None. I say it is not about treating ourselves to a treat. It is about living every day with the intention that it is a day worth doing something. And if quality is not an integral part of that, then what is the joy of life? Give it your best… Good beer. Good friends. Good whiskey. Good work. Good food. Coffee. Love. Sex. Freedom. Coffee. (Did I actually say coffee twice?)
So anyway. First things first: the roaster.
Simply stated, I want a small device that will allow me to articulate, experiment, and otherwise roast coffee to what I hope will eventually be a very fine degree of precision. One that will evenly distribute the heat through the drum, one that will be also be highly responsive to the application of heat (competing agendas, really). But more than trying to achieve the “perfect” machine (can that exist?) I intend to build one that will allow me to alter it in order to experiment—change drum dimensions, change drum materials, change drum design and know how each shift in materials, in dimensions, in design, affects how the roast progresses.
I have no illusions that this roaster will be what make good coffee. I named this experiment Deft, afterall. I wrapped it’s name around skilled fingers, around the notion of manual labor. What moves the fingers? The soul. Passion drives the soul. And without someone, someone with vision seeing where to take the coffee, then it is simply lost.
So anyway, back to the device itself. Here is my checklist:
Roast 0.25 – 1.25 lb (green) coffee, continuously
Roast so evenly. Very evenly.
Infinitely adjustable flame, such that the roast can extend between absurd extremes (4min roast to 25+min roast times- this is about being able to stretch or compress sections of the roast, not getting a 30 min roast.)
Able to replace drum with other composition, other dimensions
Able to adjust drum rotation speeds
Able to easily (relatively) change out flame design (design of the flame delivery)
THE DRUM SHOULD:
Distribute the heat. Evenly.
Allow the roast environment to be highly responsive
Be non-reactive to the coffee (wrt to the flavor) – traditionally, drums have been made of mild carbon steel, but Stainless Steel is intriguing to me…
1) Steel (mild, carbon)
2) 317 Stainless Steel/Copper
3) 317 SS/Aluminum
4) 317 SS/Copper/Aluminum
5) 317 SS/Mild Steel
