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Homeroasters - Home Roasting Coffee Community » ALL ABOUT ROASTERS » Gene Cafe Roaster

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Trouble with consistency - Looking for a little advice!
korebo86	#1 Posted on 01/10/2021 8:15 PM
Newbie Posts: 5 Joined: January 10, 2021	Hey all, first time posting on the site - looking forward to joining the community! I recently got a gene cafe and I can't for the life of me seem to get an even roast. Most of my roasts have followed one of the below profiles: 1. Pre-heat to 450, drop and heat on 482 until FC, reduce to 460 and pull out around 20% dev time (usually around 11 minutes or so) 2. Pre-heat to 350, drop and heat at 420-440F for 3-5 minutes, up to 460F until FC. Raise to 482F for a minute, then drop back down to 460 until the end of the roast. I really love Ethopian beans - being work with these: https://burmancoffee.com/product/filter-by/fruity/ethiopian-washed-yirgacheffe-gr-1-idido/ Almost all of my roasts have been acceptable - one coming out really great actually, but the majority are uneven, or even scorched/tipped. Not sure what I'm doing wrong here! Pic attached to my recent roast. Left is one I'm trying to emulate, the right is mine :(. Although random questions: - How do you all measure bean temperature? Is it possible without heavy mods to the gene? - Are there beans I should start with, are "easier" to work with? Thanks in advance all and appreciate any help you can offer! MG korebo86 attached the following image:


renatoa	#2 Posted on 01/11/2021 1:39 AM
Administrator Posts: 3005 Joined: September 30, 2016	I would try the "magic profile" of Jim Schulman: Quote ...starting temperature of around 325F to 400F (163-204C), and a ramp up to around 450F to 480F(232-250C) in around 6 to 8 minutes, and holding it steady there to the end of the roast, whenever that may occur. Also, uneven roast on gene usually means too much load. Charge 10% less. There is no way to measure BT, the mods to get something realistic are indeed heavy. A much simpler but effective mod would be the external dimmer, to have a constant and reproducible heat input, instead the actual on-off with 50 C temperature swing. Depending on your mains voltage you could have even 350 C input temperature when relay ON, which explain scorching. Having a known and constant input temperature, will be easier to roast using the rule above instead relying on BT.


jkoll42	#3 Posted on 01/11/2021 5:51 AM
1 1/2 Pounder Posts: 860 Joined: February 14, 2011	So scorching/tipping is from too much heat being applied to the bean. This can be from a ton of reasons but the fact you are seeing both scorching AND tipping as well as uneven roast would indicate not enough bean movement for the heat being applied. Like ret said try reducing the bean load. As far as beans, you can get more 'wiggle room' using a dense high grown bean that is fresh and has a proper moisture level. They tend to hold up to less than ideal roasting better. It's not guaranteed but Guats and Kenyan typically hold up better. If you go onto SM site look for beans that give a roast range that is forgiving to FC or are listed as good for espresso. They are more likely to at least partially cover up the roast defects you are seeing until you get things sorted out. -Jon Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3


renatoa	#4 Posted on 01/11/2021 6:28 AM
Administrator Posts: 3005 Joined: September 30, 2016	Exactly, whatever you get, try to be fresh, with guaranteed crop date not older than fall 2019. Learning roasting on cheap beans is one of the worst way to fool yourself about saving... because cheap means old crop usually, the hardest to roast even by pros.


jkoll42	#5 Posted on 01/11/2021 3:34 PM
1 1/2 Pounder Posts: 860 Joined: February 14, 2011	Quote renatoa wrote: Learning roasting on cheap beans is one of the worst way to fool yourself about saving... because cheap means old crop usually, the hardest to roast even by pros. Yup - I think I still get nightmares from a batch of cheap old crop low grown beans from Brazil -Jon Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3


korebo86	#6 Posted on 01/11/2021 6:21 PM
Newbie Posts: 5 Joined: January 10, 2021	Thanks everyone for the replies, to be honest it's pretty awesome to be able to ask questions on the forum. Renatoa - I'll try the magic profile you mentioned on my next go around. What do I charge it at? Do I pre-heat to 325-400F or put them in at room temp? jkoll42 - Took your advice and ordered some Kenyan beans from sweet marias. The beans I was roasting seemed like a good batch from Burmans - how would I be able to tell if they are stale / old? Crop date like you mentioned? I've heard about the dimmer mod. I just bought a killometer to charge voltage on the outlet I use. Was thinking this dimmer mod but i can't for the life of me find the actual instructions. Any ideas? Thanks again!


renatoa	#7 Posted on 01/12/2021 2:52 AM
Administrator Posts: 3005 Joined: September 30, 2016	surely you preheat, else the first 5 minutes the gene glass will absorb all the heat. This is one of the most complete page about dimmer mod, especially the explanations why you need to do this: http://coffeetime...od-stage-1 Instead that knob dimmer I would use a more precise digital model, like this: https://www.amazo...82-1002562 It can be done even simpler than the article above, without opening gene. You simply connect the box above between the mains and gene plug. You get a sacrifice power strip, cut the cord, connect the input power terminals to mains, and gene to output terminals, and this is all, you have a controlled variable voltage power source at home.


korebo86	#8 Posted on 01/12/2021 7:05 PM
Newbie Posts: 5 Joined: January 10, 2021	got it - just making sure! Yea this dimmer mod looks a little more technical then I thought. I'm worried I'd break it. I'll try your magic profile and see how it goes. I'll try charging it at a lower temperature and hope that avoids scorching.


jkoll42	#9 Posted on 01/12/2021 7:45 PM
1 1/2 Pounder Posts: 860 Joined: February 14, 2011	A (reputable) bean supplier with arrival date details is really the only way to get a gauge on how fresh the beans are. If they don't list dates then you sort of have to play a guessing game based on when harvest season is for the origin and hope it's from the current season and not a prior season. Over time you can get a nose for how strong and specific the smell of a recent harvest green bean that has been stored and processed correctly but I don't trust my nose that much! The reason I direct people to SM is Tom has a very long track record of extremely high standards and transparency for bean sourcing and sale. -Jon Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3


renatoa	#10 Posted on 01/13/2021 3:02 AM
Administrator Posts: 3005 Joined: September 30, 2016	Quote korebo86 wrote: got it - just making sure! Yea this dimmer mod looks a little more technical then I thought. I'm worried I'd break it. I'll try your magic profile and see how it goes. I'll try charging it at a lower temperature and hope that avoids scorching. You can charge as low as you want, that inbound hot air is always much more than outbound, shown on display... The graph from the article shows you that the inbound hot air temperature at top is more than the maximum advisable of 270 C. Actually, it depends A LOT on your mains voltage. The lower the better. I have a friend whose mains is well under the standards, in the 190-199 V range, his gene is not able to achieve 245 C degrees even in one hour, but his roasts are fabulous, exactly for this reason ! My home mains is 237 V atm of posting, and I measured even 350 C inbound hot air top temperature ! If not a dimmer do yourself a favor and get a long AND THIN extension cord, 20 meters of awg20 should drop about 10 volts, about 30-40 C degrees lower temperature, making the beans a lot happier.


korebo86	#11 Posted on 01/24/2021 10:25 AM
Newbie Posts: 5 Joined: January 10, 2021	Hey all just wanted to give an update. I tried the magic profile using a 250g batch and the beans came out very nicely!! Still a tad darker then what I?d like but going to work with this profile. It?s interesting, I did 3 batches. The 1st was uniform, but the second had a bit of scorching. So for the third I put the gene in cool down, and when it was done, preheated to 350 and the beans were as uniform as the 1st batch. My guess is the air temp went down between 1&2 but the drum was still retaining a lot of heat. So thanks again for the awesome advice!!!


korebo86	#12 Posted on 01/24/2021 10:26 AM
Newbie Posts: 5 Joined: January 10, 2021	Oh and I also used a meter to check voltage. It was steady at 120. Went down to 199 and up to 122 a few items (like twice).

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