Looks like my roaster is shipping tomorrow morning out of Brazil.. I am bouncing off the walls in anticipation.
Tag Archive for 'sample roaster'
I can hardly stand the slowness that designing and building this roaster is. I know that it is my doing, but that doesn’t make it any easier not being able to really control my roasts. And it’s becoming increasingly painful as I become ever more eager to sink deep into cupping coffee and reaching balance with a roast. I’m not currently exploring as I know I am able… and truly return to my craft.
Well, In fact I couldn’t let this go any longer, and so purchased a sample roaster from Pinhalense.. I just got word at the end of last week that it is essentially ready in the factory as of tomorrow, so all it needs is some crating, an airplane, one long flight from Sao Paulo to Portland. Some gentle customs agents, and a van to get it home. If all goes well, by next weekend, I should be tearing through some junky green that I’ve been stashing away over the past couple months to get it nice and seasoned.
Okay, three last images. They simple show the difference in air flow for low and high air flow. Noticeably more chaff gets around the corner with high air flow.Here they are:
Low air flow:
High air flow:
Comparison of high and low air flow - the magenta overlay shows the difference when the high airflow was done (second):
I think that I have a bit more figured out and will post when I have a chance to scan a couple drawings… But I think that what I’ve landed on is a relatively simple air path that draws air via two different paths—one entering through the bean chute, through the drum and out the back toward the chaff collection box; the other entering through the bean tray (cooler) and hooking up with the chaff collection box, where both paths meet and out the door…
What is nice about this is I can essentially seal off the chamber where the heat source is located and around the exterior of the drum so that I can make this temperature stable and so controllable and responsive.
I am figuring out the design of the air flow—mostly to allow for control of the air flow, but will need to catch the chaff as well. I based what I am doing on what I know of older Gothot sample roaster —why reinvent this? I don’t have one to play with, so am reverse engineering based on my memory and images I have found on the internet.This video is of the easy portion—where the air exits the roaster and enters / moves through a wind tunnel of sorts, separating the chaff from the airflow. you can see where the chaff is caught in the dead zone below the hole it enters through. Still a couple refinements to figure out, but it is working.The Cheesecloth was there cause it is a normal fan and not a n impeller, and I wasn’t sure it would work (well, it didn’t at first, which is why it is version 1.3 -)
I’ve been making on the fly tweaks to the form of the air box, and have almost nailed down the general design. It is based on older Gothot sample roaster designs that I have seen. I am basically re-creating this from memory and what images I could cull from the interweb. I don’t feel that I need to re-invent this part of the roaster, but am toying with how to build some efficiency into the heating, similiar to how the Kestrel roasters work. That may be phase two though.I need to run through the tests again, but feel that I am fairly close.
Learnings:
Having the air/chaff enter from an overhang (rather than flush with the back wall) creates a nice little dead zone that traps chaff quite well
That if the gap leading to the exist hallway is too large, the fan/impeller will simply pull all the chaff around the corner and out the venting—with lower airflows. The final design will have a slit of a gap.
I may add a fine mesh screen in front of the impeller entrance just to catch any errant flakes, but they could also be caught with t-shaped venting after the impeller (which I should do anyway). A tiny bit of chaff isn’t going to hurt the impeller, after all.
Next I want to repeat this with a larger amount of chaff, and with dry ice (to see what it looks like). and then begin dimensioning this out. I like that it’s really simple and works.After that, I need to add on the air as it comes from the cooling try, which sits on top of the airbox. It’s a bit more tricky, as it will feed both the airbox and the drum—toggling between the two…
Thanksgiving day, Christy drove the girls over to our friends home for dinner while I walked. I was getting a bit squirrelly and the fresh cold air was exactly what I needed. Almost immediately, my mind was engaged with this experimental roaster. I’d been stagnant with any progress since the soapbox derby, and i was really wanting to get back with it. But I was hesitating for some reason.
One of the things that has been nagging at me has been airflow… I had convinced myself that the airflow for roasting 1/2 to 1 pound of coffee wasn’t as important as the drum and bean mass dynamics. Minimal in fact and so I didn’t need to put too much consideration into it… as long as I drew air through the back and out of the front of the drum (the front end was going to be open, like Gothot / Probat and Pinhalenze sample roasters) I believed that I would be able to achieve good control over the roast. But the venting and control that the Gothot has was just sitting there in my mind, picking at my certainty, pointing out that even in small batches, air flow is important.
So I was walking through the neighborhood and re-worked almost everything. Not so much in detail, but mentally re-sketched the entire plan for the roaster. and so now it is more like a grown up roaster, with control over the air flow so that I can control it subtly.
Which brings me to today. I am not trying to re-invent anything, and so built a prototype of the air box based on what I know about the Gothot sample roasters.. an so far just have the chaff collection part built. I should be able to test it in the next couple days and will post images and video of it shortly…