Roasting with rotisserie oven

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
tedlegrand

#1: Post by tedlegrand »

I wanted to find a less expensive option than the behmor 1600+ to roast larger batches than the popcorn hopper. I have great control with my modified popcorn hopper including variable heat and k-type probe, but the 50g capacity means I have to roast 8batches per week. On a budget, the sr500 doesn't roast much more than 100g, it's an improvement but there's also wait time in between roasting where as with the popcorn hopper, I roast 4 batches back to back.



Generally, roatisserie oven don't have high enough temperature to properly roast. I came across gourmia geo3000 oven https://www.amazon.com/Gourmia-GEO3000- ... 01M73QZUT/ that has some positive reviews about roasting coffee. For 80$, it already come with a roasting basket, so I decided to try it out.

The first batch took 20+ min at max temperature. It came out baked without going through first crack.

Since at max temperature, the elements was cycling through on/off, the machine probably can heat higher.

So I opened it up and found that just by twisting out the max heating stop, I can easily make this thing reach higher temperatures.



So second try with heating elements always on , I reached first crack in 4 mins, temperature wise, good enough, but the beans finished with very uneven roasting. Way past second crack on one side of the drum and city on the other side.

Next step was to see if the rotation speed can be increased. Easy enough, it has a swappable synchronous motor. I switch the 2.5rpm motor for a 15rpm motor https://www.amazon.com/Turntable-Synchr ... 01ICNZNQM/
result: uniform easy roasting.






Next step would probably add some finns inside to move around the beans even more

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espressme

#2: Post by espressme »

A good idea and better implementation of it! Thank you! When I started, I tried many of the differing possibilities of pop corn roasters, Finally bought a Behmor. Your idea here is great and I can see many great possibilities for it.

~Richard
richard penney LMWDP #090,

renatoa

#3: Post by renatoa »

Try to adjust your thermostat to open at maximum somewhere below between 245-260C, 4 minutes is too fast, and also you don't have any safety against a fire.
Ideally the temperature should reach 175-200C between 3-4 minutes from charge/start, and 230-245C at about 6 minutes mark, with FC in the 8-10 minutes interval.
Easiest this can be done with a $20 PID, thermocouple mounted in the thermostat location and SSR replacing thermostat.

tedlegrand (original poster)

#4: Post by tedlegrand (original poster) » replying to renatoa »

Thanks for the tips, i'll fine tune for the next roasts by monitoring the temperature with k-probe. With the beans rotating faster, the first crack appeared around 8min vs 4min with the slow drum speed.

There's a safety cutoff thermistor in the main power in.

tedlegrand (original poster)

#5: Post by tedlegrand (original poster) »

A little update on the oven.
I've roasted about a dozen of times now 150g-400g batches. I think I get very tasty results when leaving the element ON 12-14min just until the first crack appears, then I bring down the thermostat to 475 for another 2-4min.
Gives nice evenly roasted batches of city city+

cliftonlawson

#6: Post by cliftonlawson »

Very creative. Sure beats a cast iron skillet.