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View Thread » BUILDING A ROASTER » Turbo Oven Roasters
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UFO/Turbo Oven Coffee Roaster Project
I started to roast my own coffee about a year ago. I picked up a Toastmaster popper from Target, made no modifications at all, and roasted better coffee than I had ever had at home, and just as good as anything purchased from a local independent coffee shop. Excellent coffee roasted in less than 7 minutes. My online research revealed to me that this roast time is much too fast to develop a 3-dimensional coffee flavor, and the batch size was annoyingly small. I found a Popcorn Pumper and finally the coveted Poppery I on eBay. I was able to split the wiring, add a taller chimney, and add a variac to the mix to achieve a 13 minute roast – this time a 50% larger batch size, but still too small to be practical.

On a trip to our local outlet mall, I discovered, in the Salton Outlet Store, a UFO Popcorn Popper. It seemed to be a clone of the Stir Crazy popper that so many folks are using in concert with a turbo-oven. I have owned a turbo oven for many years, and have baked dozens of chickens with it. In the store, I pulled off the stir-arm cap to see if the shaft was made of metal or plastic. I had read that many people using the Stir Crazy have to painstakingly replace their melted stock plastic shaft with a metal one. The UFO had a metal shaft. The price was reasonable, so I picked it up & thought I would give it a try with my old Turbo Oven’s top.
dmankin attached the following image:
I disabled the heating element in the UFO base. The first challenge in doing this was simply to open the UFO. It is manufactured with unusual triangle-headed screws. I found an ISOMAX Triple-Y #1" bit at the local hardware store which then allowed me to open the UFO’s base.
dmankin attached the following image:
I figured out which wire was supplying power to the heating coil, removed it from the wiring harness & capped it off.
dmankin attached the following image:
Once the heater was disconnected, I dropped some green coffee into the UFO base & flipped the power switch on (yes, the UFO has an on/off switch – the Stir Craze does not). The green coffee was aggressively stirred around. The stir arms spun with enough force and speed to quickly push beans over edge. I clearly had to build some sort of barrier to keep the beans under control.
dmankin attached the following image:
I fashioned a spacer ring from a springform cake pan. I fastened the ring to the UFO base with a homemade harness which I fashioned out of springs (disassembled a plate hanger - from Michael’s Crafts). This spacer was about 3 inches tall.
dmankin attached the following image:
My first roast attempt held a few surprises – some good, some bad. The first discovery was that the turbo oven slid around endlessly, forcing me to hold it still for the duration of the roast. The solution for this was to apply a bead of Permatex High-Temp Red Silicone Gasket Maker. It is rated for 600 degrees F +, and can be used for oven door seals, so I figured it can be in close proximity to food prep safely.
dmankin attached the following image:
Discovery #2 – The agitation of the beans is forceful enough to actually eject some beans out of the chaff-ejection (thank you,WOZ!) slit. I looked around and found a metal strip that is from the back of an old PC case – used to cover an unused slot. I bent it to fit the springform shape & ‘red gooped’ it into place. This fix really works well. I have done a dozen of roasts since this mod, and have not lost a single bean! Beans do tend to collect on the “edge of the pool”, so I wallop the side of the UFO every minute or so with a wooden spoon – very low tech, but very effective!
dmankin attached the following image:
Discovery #3 – The roast times were running long – about 20 minutes, so I drilled a hole in the UFO body to allow a digital thermometer probe to enter the chamber – just above the stir arms. I found that once the beans expanded, the probe actually sat in the bean mass.

Note: There are a few "Euro Strips" on the stir arms - many folks on CoffeeGeek forums use these on their Stir Crazy roasters. I plan to remove them, since others have mentioned that the UFO's stock stirring arms move the beans sufficiently on their own.
dmankin attached the following image:

Edited by dmankin on 12/23/2006 09:28
The temps seemed a tad ‘mild’, so I thought I’d try to fashion a shorter spacer ring, allowing the heat source to rest closer to the beans. A trip to Home Depot led to an aluminum strip purchase. The strip is 1.5 inches, cutting the spacer height in half, and bringing the roast times right into zone. Unfortunately, this aluminum strip is killer thick – so thick, in fact, that I had a bear bending it into the round shape needed. I fought this problem with various kitchen pots & clamps, bending, clamping, and bending more until it matched the UFO’s diameter – not a recommended thing – find thinner metal. Instead of running a red goop bead on this new ring, I bought a length of high-temp silicone tubing from US Plastics (3/16" ID x 5/16" OD). It was 60 cents per foot, available in 10 ft. increments. A slit with scissors made for a quick fit. The turbo oven sits firmly & does not move – nice.
dmankin attached the following image:

Edited by dmankin on 12/23/2006 19:17
My typical roast size is exactly one pound. I tried to push it higher, but the roast time lengthens a bit too much, and the motor tends to reverse more than I like. Roasts seem very even to me, and I can roast to any desired level. The UFO/TO is not noisy, so both first and second crack are quite audible. The turbo oven’s glass dome allows me to see the beans clearly, enabling constant color monitoring.

Until very recently, all roasts were performed with the turbo oven set to its highest temperature setting throughout the entire process. I also preheat the unit for 3 or 4 minutes – just so the beans aren’t dumped into a cold environment. I have just started to experiment with mid-roast temperature tweaks. I let the beans reach 1st crack at full oven throttle, and once 1st begins to settle down, I lower the temp. setting a bit in order to stretch the period between 1st & 2nd crack.

Here’s a very inexpensive way to roast a 1 lb. batch of green coffee, allowing good control over the process. This experiment is a work in progress. I can’t walk into a hardware store or kitchen supply shop without looking at everything and wondering how it can be strapped onto my UFO/TO roaster!

Click (or copy & paste the following url) to see a video of my UFO/TO Coffee Roaster in action!:

And finally - a cup of my homeroasted coffee!
dmankin attached the following image:

Edited by David on 12/24/2006 03:50
Nice Job! s:1s:2s:1s:2s:1s:2s:1

Eddie Dove

The South Coast Coffee Roaster
vita non est vivere sed valere vita est
Home Coffee Roasting Blog and Reference
Here's the turbo oven sitting on top of the UFO (with original springform cake pan spacer)
dmankin attached the following image:
Fine job, Dave. Thanks for taking the time to document this for us.
Great photos and details...s:1s:1


Using your instructions, I will see what i can do to mod my UFO this week-end.

I'm so glad you got around to posting this. What a terrific way to roast!! Your description will help so many people tackle this project.


Using your instructions, I will see what i can do to mod my UFO this week-end.


Good luck on the UFO mods. I'm near my computer for most of the holiday season, so give a shout if you have a problem, or a louder shout if you find great success!


Dave :)
Edited by dmankin on 12/23/2006 19:28
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Orville Redenbacher was a genius - just misguided... COFFEE, Orville, COFFEE!
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Blogging because I think I'm supposed to:
David, Whenever I want to convince someone that getting set up for home-roasting doesn't have to cost an arm & a leg I refer them to this thread.

Keep up the good work!
It's not expensive at all, those first steps out onto the slippery slope.

Thanks, Tex. This roaster is still going strong after 2 years of weekly use! The coffee is consistently terrific. c:1

................................ ...............................
Orville Redenbacher was a genius - just misguided... COFFEE, Orville, COFFEE!
................................ ...............................
Blogging because I think I'm supposed to:
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