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11/26/2020 6:37 AM
Everyone have a super Thanksgiving and may all your roasts turn out stellar woohoo

11/25/2020 4:20 PM
Howdy 1st CH and welcome to HR forum! Be sure to read in the forums to see if anything covers the topic and please post away in drum roaster forums Welcome

11/25/2020 3:35 PM
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Idea for halogen roaster
Danyboy
Hi guys,
New to the forums here, but been reading as many threads as possible. I wanted some input as to whether the following idea would be workable based on your collective experiences, prior to embarking on a potentially dead end journey. I would like to roast 300-500g of coffee.

What I'd like to build is a halogen roaster that would resemble a Behmor. I would use an old toaster oven as the casing (would gut the electronics), and put in a mesh drum (the $10 ones on ebay) attached to a 30ish rpm worm drive motor.

As a heat source, I was thinking of attaching 2-3 halogen bulbs between 700-1000 watts each (2 x 1000 or 3 x 700) to the inner walls of the oven, at an appropriate distance from the drum, maybe ~3cm. The advantage of having multiple bulbs would be to have some degree of control over temperature. They are also very cheap ($3 on ebay for 1000W lamp)

What I was more worried about were the following:
1. Air flow - would there be any advantage to having a fan to circulate air within the oven? I was thinking about having a closed air circulation circuit (using ducting) with the possibility of a vortex for chaff collection. The advantages of the closed circuit would be less heat loss and possibly additional heat delivered to the beans for drying/roasting. My main concern would be finding a fan that can function when subjected to the temperatures of a roasting chamber.

2. Cooling - There would be no easy bean dump due to the form factor. Instead I was thinking of the above concept of air circuilation with the option of having the air intake from outside the oven instead of recircuilating (either by having a mobile port to switch the air intake from inside to outside). OBviously would need to be a powerful enough fan - eyeing fans with a cfm > 500

3. Heating - the alternative to 2-3 halogens would be to have something like a ceramic heater for IR + a halogen lamp.

Would anyone care to give me some feedback as to whether they see any obvious problems, or whether similar projects in the past have failed/succeeded? I've read through some of the threads describing halogen ovens that people have built, but unsure how that would relate to my design idea...
renatoa
Used for some 6 months a similar approach, i.e. drum in an enclosure, and abandoned due to the hassle of loading and dumping beans = handling of a hot potato... er. drum :)
Also, measurements inside a drum aren't that simple.
Other notices:
- power is over-estimated, 1kW is enough for 500 grams. I am roasting atm up to 650 grams using 1400 W, that are fully used only 2-3 minutes in the dry phase, then power is reduced to less than 1kW, even less than 500W in development phase.
- airflow is a must ! using a turbo oven lid, that includes a turbo fan, is the simplest and cheapest solution. Else chaff will stay in the drum and burn => smoked coffee.
- cooling is indeed difficult for drum approach, but much easier when using a flat pot with rotating agitator, like stir crazy. You simply remove the halogen lid and place a fan of same size above the beans, no more need for dump until beans cold.

A solid drum approach with halogen inside, that broke my jaw, not so difficult to replicate, can be found here:
http://www.dbr.co.nz/radiant.html
The build has a thread somewhere here, with some additional explanations that were asked by users.

Or, if still loving the behmor style of roasting, evaluate using a George Foreman ove, seems the most appropriate for such task, with some success stories around.
Still many issues to solve even for GF approach: faster drum turn, chaff management, airflow...
DIY: TO based IR 750g
Moded commercial: Dieckmann RoestMeister, Nesco, popper(s).
TC4ESP, MS6514, USB/Artisan/Apps, PID controllers
Grinder: MBK Feldgrind, mod'ed Porlex to 47 conical burrs, vintage PeDe Dienes, Kinu M38
Gaggia Mini, Aeropress, drip
renatoa
A second read notice, 3 cm from the drum is too close, could heat the metal more than 300C => beans scorching/tipping.
Several sources points that the shortest safe distance for direct to bean heating is 3"/8 cm.
Danyboy
Hmm thanks
Good to know
8cm - will need to get a large enough toaster oven and figure out how much volume the bean mass occupies to get the dimensions right
Will definitely try for a solution with air flow. Wondering if there are any fans that can handle the heat...
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