# Help me get rid of scorched beans / uneven roast



## MediumRoastSteam

So, I've been using a modded Gene Cafe now for a few months, and recently put two kilos through.

Every single batch came out with scorched beans. I've tried lowering the amount of beans in the chamber, I've tried a gentle rise, I've tried not so gentle rise. I've tried 250g, 230g, 220g, all to no avail.

One thing I've noticed though: I noticed some chaff accumulation on the chamber's exit grille (I always clean before and after each roast) and I am starting to think all of this may be due to a poor air flow on the Gene.

I've checked the air filter gauze, and it's so clean you can actually peep through the holes and see the inside of the Gene.

Could I have a duff fan? Is there a way to test if my fan is blowing enough air?

Thanks in advance!


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## Simon_S

I've been on the brink of starting this self same thread for the last few weeks, after trying all the above fixes to no avail....

So frustrating!


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## Rob1

You're going to have to provide more information. What is a gentle rise etc? What temp does the Gene reach? When do you notice the scorching? Some beans can take a lot of heat and some can't so bean size and density is relevant. In run the gene at full power until 230c and then switch in the dimmer at 1150w (at 245-250v) and I don't get scorching. If you run a batch and your air flow isn't good the element will switch off before reaching temp.


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## MediumRoastSteam

Rob1 said:


> You're going to have to provide more information. What is a gentle rise etc? What temp does the Gene reach? When do you notice the scorching? Some beans can take a lot of heat and some can't so bean size and density is relevant. In run the gene at full power until 230c and then switch in the dimmer at 1150w (at 245-250v) and I don't get scorching. If you run a batch and your air flow isn't good the element will switch off before reaching temp.


Thanks Rob.

Gentle raise: I've tried full power to 220C, then hold there for 1m (I found that 1100W holds the temp nicely), then full power to 230C, hold for 1m, and then full power again to 235-238 until F.C. , back to 1100W, stay there until desired colour and cool down.

I've also tried 220 -> 230 -> 238 without the mod.

I've also tried gradually ramping up: from 7min into roast, gradually increase the wattage from 1100 to 2000W. That was rubbish: hard beans, baked, awful. Yet, scorched and uneven.

I roasted last Brazil's naturally processed and Peruvian washed.

The element never switches off during ramp up or at all. I only noticed switching off once at the end of the roast, very briefly, snd that's when I noticed the chaff blocking the exit of the chamber. I've subsequently roasted after that and never noticed the element turning off.

Scorching: I noticed that, after they turn yellow and becoming brown, some are more brown (roasted) than others. When the roast is finished, I notice that they all have some kind of scorch marks.

What intrigues me is that, when I see some posts on the "today roast" thread and the beans are so even, and those guys are using the Gene - I think I've seen a few from you too - the roast looks great, and mine don't even look anything like it. I think Iroko just uses a stock Gene Cafe, just leave the Gene to do its job and what I see are very even beans. I tried that myself, and the result was very different.

Ps: I'm happy for a suggestion of beans and a profile to try it out


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## Rob1

It's been a while since I roasted Brazils and I think I've only ever had 1kg of Peruvian. From what I remember Brazilian beans tend to burn easily and require a more gentle approach to roasting but it will vary depending on altitude. They should be rated as hard or soft beans or have the altitude detailed on the packaging/description. Some beans roast unevenly with a wrinkled looking surface. I've had plenty like that and they look uneven but then suddenly even out in the drum. To eliminate scorching I don't know what to suggest other than limit your maximum temperature and control your wattage. Make sure it isn't skipping up as you watch the beans. What's your voltage?

I'm not sure why you're holding at 220c or 230c etc for 1 minute. I used to do permutations like switching the dimmer in and out, using different wattages at the different stages, but it didn't help. My roasts have improved with just running either with declining profile like 1150w until 165c (BT) 1130w until first rolling 1100w until first end 1080w-1050w until end of roast. Or with running at full power and switching the dimmer in to run at a target ET with a target wattage depending on the roast depth and first crack length I want. I struggled with scorching on a Panaman bean a while ago and I had to use something similar to the above profile as the scorching as the beans yellowed -- they couldn't take the heat at full power. I always struggled to get anywhere close to second crack with them without burning/scorching. It's frustrating but fighting against your roaster is impossible.

Have you recorded the times for your roast?

You let the temp hit 220c then switched in the dimmer at 1100w and held it for 1 minute. Then full power to 230c and held it there how? 1100w again? Then full power again until FC at what time?

Give the following a spin:

Full power until paling (approx 4:30-5:00 minutes).

1150w until Browning.

1130w until FC rolling.

1100w until FC end.

1080w declining after 30 seconds to 1050w until roast end.

That should take you through to a finish BT temp of about 230c so Full City+. You're going to have to adjust depending on whether you get scorching again (start from 1130w) or if it takes ages to reach first crack and it progresses slowly (1150w until start of FC (you smell it before you hear it)). If you want to hit second crack you might not lower to 1130w on rolling you might just let it run through and drop to 1100w as the pops slow down. The gene readout 'ET' (it isn't the ET) will also determine when you switch wattage if you have found you get scorching when going above a certain temp. I get very slight scorching on El Salvador Red Bourbon at 235c so I limit it to 230c and alter my power to stop it from rising above that. I never let the element switch off (it's set as high as it can go to keep it out of the way).


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## MediumRoastSteam

Thanks @Rob1.

I've also followed your decreasing temp profile from Today's Roast, and, the results didn't look any encouraging, at least with the beans I'm using. I've bought 1kg of Colombian Suarez from Rave so will give that a go next.

I'll give it a go again to the decreasing profile and will report back.

My voltage on the last roast was 239 / 240, but it is usually 237 / 236.

I did monitor the temp raise, minute by minute too. Seems fine.


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## Rob1

If you've already done what I've described above there's no point trying it again as your results will be the same. Voltage is low if you're on a 240v element so I'd think you'd struggle to increase temp rather than have to deal with it getting too hot too fast. The key to stopping scorching is to not roast too hot and/or fast. If you aren't getting scorching early in the roast logically you're getting it when you increase the temp above 230c. The uneven colour as the roast progresses could be due in part to your permutations and just the way the beans roast.


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## MediumRoastSteam

@Rob1.

Could it be that the "Full Power" can be scorching the beans? I could try as you suggest keeping steady at 1150W and then lower as I get to first crack as an experiment.

My worry is that I might have baked coffee instead of roasted coffee at the end.

And indeed, I do have a 240V element.

Anyway, I'll try that and see what happens.

Question: do you get chaff accumulating on the exit grille of the chamber? How much do you load it with? 250g?

Thanks again.


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## Rob1

250g I don't really. If you've got a natural you'll get more chaff and should lower the batch size. Full power won't scorch until the drying stage has ended (as the beans pale just before turning yellow). You won't get baked so long as the temp of the bean continues to rise.


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## iroko

MediumRoastSteam said:


> So, I've been using a modded Gene Cafe now for a few months, and recently put two kilos through.
> 
> Every single batch came out with scorched beans. I've tried lowering the amount of beans in the chamber, I've tried a gentle rise, I've tried not so gentle rise. I've tried 250g, 230g, 220g, all to no avail.
> 
> One thing I've noticed though: I noticed some chaff accumulation on the chamber's exit grille (I always clean before and after each roast) and I am starting to think all of this may be due to a poor air flow on the Gene.
> 
> I've checked the air filter gauze, and it's so clean you can actually peep through the holes and see the inside of the Gene.
> 
> Could I have a duff fan? Is there a way to test if my fan is blowing enough air?
> 
> Thanks in advance!


My gene is standard, I get chaff build up at exit grill but It always gets blown through. Does the chaff in yours not get blown through ?

I do get a few scorched beans but nothing bad.


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## MediumRoastSteam

iroko said:


> My gene is standard, I get chaff build up at exit grill but It always gets blown through. Does the chaff in yours not get blown through ?
> 
> I do get a few scorched beans but nothing bad.


They do, but at the end of the roast I still have chaff sticking there.


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## iroko

I have no chaff left at the end of roast, is there enough chaff to block the air flow at the end of your roast.


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## MediumRoastSteam

iroko said:


> I have no chaff left at the end of roast, is there enough chaff to block the air flow at the end of your roast.


That's what I'm suspecting Iroko. It's getting too hot in the chamber, without a good airflow, and the beans are getting scorched.


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## johnealey

Check the flappy thing (technical term







) is correctly cleaning the chaff away from the vents. The only time have had this was when I had somehow managed to stretch the round spring wires whilst cleaning the chamber separator. Quick call to BB and Claudette sent me some little spring things to replace the stretched ones. PITA to fit (needle nose fine pliers a must) but once done problem solved. You could also replace the chamber separator here then would allow you have one clean ready to go and one in use (cafiza works a treat on these)

Whilst this may not be the answer assuming you unscrewed the chaff collector to clean behind the screen and vacuumed the underside of the gene where the dust screen is on the air inlet, it might get you some of the way to dealing with the chaff issues if nothing else.

John


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## MediumRoastSteam

johnealey said:


> Check the flappy thing (technical term
> 
> 
> 
> 
> 
> 
> 
> ) is correctly cleaning the chaff away from the vents. The only time have had this was when I had somehow managed to stretch the round spring wires whilst cleaning the chamber separator. Quick call to BB and Claudette sent me some little spring things
> 
> John


These?










Just checking, they don't have any spring effect do they? They are just rings to hold the flap in place?


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## johnealey

Yes, hard to tell from the picture but are these solid rings or coiled wire similar to a key ring holder?

John


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## MediumRoastSteam

johnealey said:


> Yes, hard to tell from the picture but are these solid rings or coiled wire similar to a key ring holder?
> 
> John


They are coiled like a key ring holder.


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## johnealey

Then they may be stretched enough to interfere with the way this paddle affair works getting caught and then on the down swing coming in too high to break the chaff up, (if you watch it when there is chaff there you will see what I mean) and it does sound like it is not making contact enough.

The only way you will know if it is this or not is to try either replacing the rings or the chamber separator.

John


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## MediumRoastSteam

@johnhealey, @DavecUK, @Rob1

So today I noticed chaff accumulating on the exit grille of the roast chamber. The flap was swinging happily, but not doing much.

So, I removed the chaff collector all together and.... Voila. The chaff started to clear away from the exit hole in the chamber quite rapidly.

I then did another two batches to confirm my theory, and yes, I can visibly see the grille pretty much clean thru the roast and also there doesn't seem to be much chaff left on the beans themselves compared to before, a considerable improvement for sure.

I hoover the chaff collector after each roast, and also brush it. As far as I can see, there are no blockages.

What do you guys think this could be? I've mentioned you in this post as you guys have a lot of experience with this roaster and roasting in general.


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## Rob1

The bean you are roasting has a lot of chaff to shed (to be expected really with a natural process) and you need to reduce your batch size.


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## MediumRoastSteam

Rob1 said:


> The bean you are roasting has a lot of chaff to shed (to be expected really with a natural process) and you need to reduce your batch size.


But why removing the chaff collector solves the problem?

Also I tried with a "fully washed" process bean. Same thing.


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## Rob1

You've previously confirmed that you've dismantled the chaff collector and completely brushed it out (from behind the metal grate), or am I mistaken? I thought somebody already mentioned doing this?...if you have then by removing the chaff collector you remove all resistance so the fan can clear the chaff more easily. That's assuming you've already followed the advice given to you of cleaning the chaff collector.


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## MediumRoastSteam

Rob1 said:


> You've previously confirmed that you've dismantled the chaff collector and completely brushed it out (from behind the metal grate), or am I mistaken? I thought somebody already mentioned doing this?...if you have then by removing the chaff collector you remove all resistance so the fan can clear the chaff more easily. That's assuming you've already followed the advice given to you of cleaning the chaff collector.


Chaff collector is completely clean throughout.


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## Rob1

You've dismantled it by unscrewing the metal screen inside it? If so then the answer is in removing the chaff collector you've removed the small amount of resistance it was giving the fan, effectively making it that bit more powerful to clear the chaff. The solution (assuming you don't want to collect the chaff by some other method) is to reduce batch size.


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## MediumRoastSteam

Rob1 said:


> You've dismantled it by unscrewing the metal screen inside it? If so then the answer is in removing the chaff collector you've removed the small amount of resistance it was giving the fan, effectively making it that bit more powerful to clear the chaff. The solution (assuming you don't want to collect the chaff by some other method) is to reduce batch size.


I did not remove the screws. I just hoovered from the bottom and from the top, by taking the upper part of the collector out.


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## Rob1

So you haven't cleaned behind this metal screen then...


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## MediumRoastSteam

Rob1 said:


> So you haven't cleaned behind this metal screen then...


Maybe I'm getting confused on which screen you are referring to. As far as I can see, it's all clean inside. If I put it against the sun or light, I can see from one side to the other. Anyway, I'll dismantle the hole thing, clean it and I'll try again next week.

But more importantly, in your experience, could it be that the fan is faulty and not pushing enough air through?


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## Rob1

I think its much more likely that you haven't cleaned the chaff collector. Without removing the metal grille vacuuming won't do much.


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## Batian

I find a bullet shaped bottle brush that is a size big enough to need a firm push into the chaff collector via the lidded hole works very well especially under a running tap.

My brush was about £1 from Aldi on 'specials'.


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## MediumRoastSteam

Rob1 said:


> I think its much more likely that you haven't cleaned the chaff collector. Without removing the metal grille vacuuming won't do much.


Any tips in removing this metal grate to I can take the panels apart?


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## Rob1

They're press fit. So not really no. They're a pain but you cab just pull them out obviously with a grip close to the hole they press into. When you remove the screws you might find it easier to pull the metal away from the little ridges one bit at a time while trying to slide the halves away.


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## MediumRoastSteam

Rob1 said:


> They're press fit. So not really no. They're a pain but you cab just pull them out obviously with a grip close to the hole they press into. When you remove the screws you might find it easier to pull the metal away from the little ridges one bit at a time while trying to slide the halves away.


Done!









The filter seems very clean, but behind there's some very fine chaff dust. Let's hope this is it! And thanks!


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## johnealey

^was what I was trying to explain much earlier about behind the screen and although it may not seem like a lot it does seem to affect the airflow over time. You may also want to vacuum the underside of below the controls as there is a fine mesh filter behind here that can also get gummed up with dust / fluff.

If all works well once above done then ignore the more recent advice re centre flappy thing rings, if not go ahead and spend the £12 plus postage on a spare one.

John


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## Rob1

I'd open the gene up and clean the fan and mesh screen from the inside too, if you continue experiencing problems.


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## RA5040

I may have missed something in this thread (in which case please forgive me!) but if not, it does seem to me that the problem is with your beans rather than the Gene. I think some Brazilian beans are pretty rubbish and come from all over the place, low altitude, high altitude etc., so it wouldn't be surprising if these give an uneven roast and even scorching. Have you tried a bean like the Colombia Supremo?

Also, you should be able to feel the airflow out of the Gene with and without the chaff collector and see if they are similar. It really doesn't sound to me like a chaff collector problem.

I've just roasted 4 batches of a washed Brazilian and they all came out fine ... but that could just be the luck of the draw!

Cheers

Robert


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## MediumRoastSteam

RA5040 said:


> I may have missed something in this thread (in which case please forgive me!) but if not, it does seem to me that the problem is with your beans rather than the Gene. I think some Brazilian beans are pretty rubbish and come from all over the place, low altitude, high altitude etc., so it wouldn't be surprising if these give an uneven roast and even scorching. Have you tried a bean like the Colombia Supremo?
> 
> Also, you should be able to feel the airflow out of the Gene with and without the chaff collector and see if they are similar. It really doesn't sound to me like a chaff collector problem.
> 
> I've just roasted 4 batches of a washed Brazilian and they all came out fine ... but that could just be the luck of the draw!
> 
> Cheers
> 
> Robert


Those are from Bella Barista, so I'm assuming it's good. Tried with some Colombian, Sumatran, Nicaraguan.... you name it... all from the good roasters we love in this forum.

I just tried the beans I roasted yesterday and they were on a different league from what I had before. I'm just wondering whether this could be due to the fact of me roasting with a smoke duct attached to the chaff collector in the winter, potentially reducing air flow and letting chaff accumulate BEHIND the filters of the chaff collectors and thus, only now, experiencing the issues reported on this thread.

Again, massive thanks for @johnhealey and @Rob1 for all the knowledge and help thus far.


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## MediumRoastSteam

@RA5040, btw, I'm Brazilian by birth. There's no "high altitude" in Brazil where coffee grows around in the São Paulo - Rio - Minas Gerais region. Most of them go through the super port of Santos. We are talking in Brazil 900m - 1500m max, hence the name of the coffee usually. More recently, single origin estates are exporting and also the hole coffee scene in Brazil is changing, for the better. It used to be rubbish where all the good stuff were exported, but not anymore. I might be biased, but I really rate Brazilian beans. Brazilian coffee beans are good!


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## RA5040

Out of interest (not trying to diagnose your issue) ... how long are your roasts, typically? And do you preheat or not?


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## MediumRoastSteam

RA5040 said:


> Out of interest (not trying to diagnose your issue) ... how long are your roasts, typically? And do you preheat or not?


I do not preheat, as advised here and confirmed by those who have been using the Gene for a while. Roasts usually last 15m, give and extra 45s for the first roast.


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## RA5040

MediumRoastSteam said:


> @RA5040, btw, I'm Brazilian by birth. There's no "high altitude" in Brazil where coffee grows around in the São Paulo - Rio - Minas Gerais region. Most of them go through the super port of Santos. We are talking in Brazil 900m - 1500m max, hence the name of the coffee usually. More recently, single origin estates are exporting and also the hole coffee scene in Brazil is changing, for the better. It used to be rubbish where all the good stuff were exported, but not anymore. I might be biased, but I really rate Brazilian beans. Brazilian coffee beans are good!


Oh, I'm sorry I made you cry!! I'm just an ignorant Irish/French/Mauritian!! Of course there are wonderful coffees from Brazil! I think mainly in past there was a lot of mass produced coffees from Brazil, so Brazil got a bit of a bad reputation ...but I have some great washed Brazilian from Minas Gerais so I can attest to the fact that Brazil does have great coffees!!

My apologies!


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## MediumRoastSteam

RA5040 said:


> Oh, I'm sorry I made you cry!! I'm just an ignorant Irish/French/Mauritian!! Of course there are wonderful coffees from Brazil! I think mainly in past there was a lot of mass produced coffees from Brazil, so Brazil got a bit of a bad reputation ...but I have some great washed Brazilian from Minas Gerais so I can attest to the fact that Brazil does have great coffees!!
> 
> My apologies!


(Sarcastic mode on)

I'm reduced to tears, I can't bear it ! 

(Sarcastic mode off)

No need to apologise! It was just a comment, nothing else. We are good! 

I grew up in southern Brazil. No coffee production there. I remember the majority of the coffee there was rubbish, and, to some extent it still is. I have gone back last year and I noticed that there are more "non staple" coffee shops popping up and, whilst the quality of the coffee has increased dramatically in my experience, I find that the majority of places still struggle to make / prepare a good cup of coffee, despite having good quality beans, great grinders and great coffee machines. Oh well, they will get there.


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## RA5040

MediumRoastSteam said:


> I do not preheat, as advised here and confirmed by those who have been using the Gene for a while. Roasts usually last 15m, give and extra 45s for the first roast.


OK ... I haven't seen a recommendation here. I both preheat and don't and I don't have much of an idea if it makes any difference. As far as I can see, preheating to 200C does reduce the roast time by about a minute, typically from around 15 minutes (for a light medium roast) to around 14 minutes. I take it that you don't preheat because you see no advantage? On the other hand, preheating does establish a starting point so 1st, 2nd etc., roasts will all start from the same point. Also (based on cooking, not roasting) it's probably a good idea to get the bean temperature up well above boiling point as quickly as possible to avoid the skin drying while the inside is still cold.

It may be worth doing a roast with a 200C preheat to see if that improves things with your Brazilian









Robert


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## Batian

You will find that the rubber bumper wears up/breaks quite quickly if you pre heat an empty drum.

I used to preheat until this was pointed out. In my first year or so I had to replace the bumpers 4 times. The next year or so, to date, after having been advised re preheating, I have not had to replace the bumper at all.

This was subsequently confirmed by an American user who contacted the Gene makers in Korea about the problem---and that was also their advice.


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## RA5040

Batian said:


> You will find that the rubber bumper wears up/breaks quite quickly if you pre heat an empty drum.
> 
> I used to preheat until this was pointed out. In my first year or so I had to replace the bumpers 4 times. The next year or so, to date, after having been advised re preheating, I have not had to replace the bumper at all.
> 
> This was subsequently confirmed by an American user who contacted the Gene makers in Korea about the problem---and that was also their advice.


OK ... so it's just a machine issue rather than a roasting one. Actually the bumper on my Gene broke after 4 roasts, I think! I drilled a small hole through the two pieces and pushed a toothpick in, making sure that the wood was well inside the rubber ... and months later my little modded bumper is running fine! But I did complain to Bella Barista and they very kindly sent me a pack free.

To be honest ... I really don't think it's acceptable that a part like that should break because of pre-heating ... it's just too small and weak: design flaw!


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## MediumRoastSteam

RA5040 said:


> OK ... so it's just a machine issue rather than a roasting one. Actually the bumper on my Gene broke after 4 roasts, I think! I drilled a small hole through the two pieces and pushed a toothpick in, making sure that the wood was well inside the rubber ... and months later my little modded bumper is running fine! But I did complain to Bella Barista and they very kindly sent me a pack free.
> 
> To be honest ... I really don't think it's acceptable that a part like that should break because of pre-heating ... it's just too small and weak: design flaw!


I had mine for almost one year. Bumper is looking good! I never pre-heat or do an emergency stop.

Also, if you DO an emergency stop, your heating element won't last as long either, and parts of your gene will deteriorate quicker.


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## RA5040

MediumRoastSteam said:


> I had mine for almost one year. Bumper is looking good! I never pre-heat or do an emergency stop.
> 
> Also, if you DO an emergency stop, your heating element won't last as long either, and parts of your gene will deteriorate quicker.


OK ... well I ALWAYS do an emergency stop because I think it's super important to cool the beans down quickly (I use a colander and fan so I get the beans cooled in 30 seconds). What I do though is to put the drum back in, get it going again and then hit the Cool cycle, so that should be just as good.

I don't really see why the heating element lifetime should be affected by an emergency stop though ... the other parts maybe, so cooling down the machine is probably a good idea. There is a lot of plastic in there.

The toothpick is the solution! We should patent it and sell it to the Koreans. But seriously, they could easily have had a little bit of reinforcement inside the bumper, and made it a bit bigger and tougher ... it's not rocket science!


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## Batian

RA5040 said:


> OK ... so it's just a machine issue rather than a roasting one. Actually the bumper on my Gene broke after 4 roasts, I think! I drilled a small hole through the two pieces and pushed a toothpick in, making sure that the wood was well inside the rubber ... and months later my little modded bumper is running fine! But I did complain to Bella Barista and they very kindly sent me a pack free.
> 
> To be honest ... I really don't think it's acceptable that a part like that should break because of pre-heating ... it's just too small and weak: design flaw!


What does the user guide say on the matter of pre heating and starting a roast after an emergency stop??


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## Rob1

The roaster isn't designed to be pre heated. You will notice the plastic warping at some point. There's no real difference between a cold start and 60c (about 30 seconds) and you can easily adjust for that with back to back roasts. The gene cooling cycle cools the beans rapidly down to below 150c within 5 minutes. The e stop affects heating element life because it's sitting there scorching hot without a fan blowing air past it.


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## johnealey

When you deviate from how a manufacturer designs something to be used you always run the risk that it will not perform in the manner intended this having been covered on a number of previous threads as well.

Of course, you can decide to use what you purchased in any manner you see fit, just don't be surprised if you have premature failure of components that cannot fairly be blamed on the manufacturer of what is really a home roaster.

Simply put,if you want commercial levels of reliability / bullet proof construction, buy a commercial type roaster but will cost you 8-10 times the amount you pay for a gene.

Have done well over 200 roasts in the little gene with only 1 failure, that was a crack in the glass drum, replaced under warranty no quibble from BB (sent a photo, next day new drum, now that's service). Have never felt the need to emergency stop it or pre heat the roaster on the first roast, I just hit cooling 20 secs before I would by look, smell etc using it more as a sample roaster these days.

John


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## RA5040

I've just read through the instructions and I could see nothing about not using the emergency stop or making sure that the roaster is cooled down using the cooling cycle. in fact, on the last page it says that if you turn off the machine by mistake 'Please turn it on again. You can take the chamber out or keep going with the roast'. So this is clearly saying that if you do turn off the roaster that you can just take the drum out. It doesn't say to make sure to finish the roast and go through the cooling cycle and it doesn't say that you must cool down the machine if you do an emergency stop, for any reason. All it says about cooling is that if you do several roasts and the machine is getting very hot to take a break and let it cool down a bit.

There is also nothing about not doing a preheat, or not running the machine with no beans in the drum. The instructions give a maximum amount of beans, but no minimum (so zero should be OK).

So if the plastic starts to melt because of a 5 minute pre-heat then there's something seriously wrong with the machine. The drum will get hotter with beans in it so if a pre-heat melts the plastic then a roast is even more likely to do so.

I do accept that it's probably a good idea to cool down the machine after a roast using the cooling cycle (and I do do that), but I cannot see why doing an emergency stop followed by a restart and cool would damage the machine. That doesn't make any sense.

I do think that a preheat is important: for instance if you were roasting nuts in an oven you would never put the nuts into a cold oven - you would end up with very badly roasted nuts. Having said that, the Gene does heat up quite quickly, so it's not quite the same thing. But a preheat to 200C will give an exhaust temperature of 150-160C after putting in the beans, and the temperature in the chamber should be higher. So we would be starting off at well above boiling point, which should be a good thing.

As for cooling: 5 minutes cooling is way too long ... which is why commercial machines dump the beans and cool them quickly. The Gene simply does not cool fast enough using the cooling cycle, so the beans will keep on cooking.

So I'm happy enough to keep on pre-heating and emergency stopping for fast cooling (followed by a cool-down if I am not doing another roast). Hopefully the machine won't break down too quickly or the plastic melt









Cheers

Robert


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## Batian

You can lead a horse to water........

Try the manufacturers user manual, Page 8.

You are roasting coffee not nuts.

Your analogy is not like for like.

A domestic oven may (or may not) be fan assisted, but it is not forcing very hot air into a small rotating chamber like the Gene. Your oven roasted nuts are taking a totally different type of heat---radiated and contact. The Gene is delivering mainly forced hot air, partial radiant heat, partial contact heat. Two totally different scenarios.

The instructions do not say not to pre heat... correct. They do tell you how to use the machine successfully, and there is no mention of pre heating. I suggest that therefore it is not required to acheive good, no fuss results?

In the days when I experimented with preheating, after seeing loads of www waffle (and finding it wrong) not only did I repeatedly damage the rubber buffer, I found that if I put ambient temp beans into a pre heated drum I often got scorching on some beans. I assumed this was caused when the beans hit the very hot metal parts and the time involved in replacing the drum and pushing start. Certainly, when doing the same batch beans using the same profile, and not preheating, scorching did not occur.

It is not the first pre heat that is going to melt the plastic, it is the cumulative effect of doing several roasts one after the other so that areas with in the machine do not get to cool down.

I do not know if it is still on YouTube, but in the early days of the Gene, (in USA) one melted and the owner posted the images. Reading between the lines, the owner was attempting to get a refund by shouting about poor kit etc. Whether he was successful or not I do not know, but if the Gene was that poorly made, we would have had more incidents?

There is a lot to be said for following the makers instructions.

I am sure if Dave C thought that preheating was an advantage , it would be in his manual. Remember, he was involved in the development of this machine for the EU market.


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## RA5040

Batian said:


> You can lead a horse to water........
> 
> Try the manufacturers user manual, Page 8.
> 
> You are roasting coffee not nuts.
> 
> Your analogy is not like for like.
> 
> A domestic oven may (or may not) be fan assisted, but it is not forcing very hot air into a small rotating chamber like the Gene. Your oven roasted nuts are taking a totally different type of heat---radiated and contact. The Gene is delivering mainly forced hot air, partial radiant heat, partial contact heat. Two totally different scenarios.
> 
> The instructions do not say not to pre heat... correct. They do tell you how to use the machine successfully, and there is no mention of pre heating. I suggest that therefore it is not required to acheive good, no fuss results?
> 
> In the days when I experimented with preheating, after seeing loads of www waffle (and finding it wrong) not only did I repeatedly damage the rubber buffer, I found that if I put ambient temp beans into a pre heated drum I often got scorching on some beans. I assumed this was caused when the beans hit the very hot metal parts and the time involved in replacing the drum and pushing start. Certainly, when doing the same batch beans using the same profile, and not preheating, scorching did not occur.
> 
> It is not the first pre heat that is going to melt the plastic, it is the cumulative effect of doing several roasts one after the other so that areas with in the machine do not get to cool down.
> 
> I do not know if it is still on YouTube, but in the early days of the Gene, (in USA) one melted and the owner posted the images. Reading between the lines, the owner was attempting to get a refund by shouting about poor kit etc. Whether he was successful or not I do not know, but if the Gene was that poorly made, we would have had more incidents?
> 
> There is a lot to be said for following the makers instructions.
> 
> I am sure if Dave C thought that preheating was an advantage , it would be in his manual. Remember, he was involved in the development of this machine for the EU market.


Now, now, I'm not exactly a horse ... more like a donkey!

The Gene manual has a LOT of warnings and do's and dont's and if preheating was a problem I'm quite sure that it would be mentioned. If a manufacturer doesn't warn you against doing something that might damage the machine (like ignoring the oil pressure warning light on your brand new Maserati) then it should be safe to do so. What the manual does say is to let the machine cool down when it starts to get too hot ... and that makes sense: so keep an eye on it, put it in a location that has ventilation (as the manual suggests), let it cool down after a few roasts.

As to whether it's a good or bad idea to preheat ... I have nothing to go by except my short experience roasting coffee, and my very long experience cooking and baking. And I have to say that I do disagree with you regarding coffee versus almonds or cashew nuts etc. They are all nuts ... or stone fruit ... and coffee can be roasted in an oven or on a hob. Just think of roasting coffee in an oven or hob ... would you put it in a cold oven or cold hob? Surely not ... it would almost be guaranteed to give a bad result. And it isn't just the speed of the Gene versus the speed of a hob or oven: a hob could heat up faster than the Gene, and certainly my oven is pretty much on a par with the Gene speed-wise.

It is true that the Gene would heat up the beans more by convection than conduction, but much less so that most other air roasters. The air-flow is very low and there are a lot of hot surfaces inside the drum (which is presumably why you get scorching when you dump the beans into a hot chamber).

But, as you say ... you can lead a horse to water, BUT ...









Cheers

Robert


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## ashcroc

RA5040 said:


> Now, now, I'm not exactly a horse ... more like a donkey!
> 
> The Gene manual has a LOT of warnings and do's and dont's and if preheating was a problem I'm quite sure that it would be mentioned. If a manufacturer doesn't warn you against doing something that might damage the machine (like ignoring the oil pressure warning light on your brand new Maserati) then it should be safe to do so. What the manual does say is to let the machine cool down when it starts to get too hot ... and that makes sense: so keep an eye on it, put it in a location that has ventilation (as the manual suggests), let it cool down after a few roasts.
> 
> As to whether it's a good or bad idea to preheat ... I have nothing to go by except my short experience roasting coffee, and my very long experience cooking and baking. And I have to say that I do disagree with you regarding coffee versus almonds or cashew nuts etc. They are all nuts ... or stone fruit ... and coffee can be roasted in an oven or on a hob. Just think of roasting coffee in an oven or hob ... would you put it in a cold oven or cold hob? Surely not ... it would almost be guaranteed to give a bad result. And it isn't just the speed of the Gene versus the speed of a hob or oven: a hob could heat up faster than the Gene, and certainly my oven is pretty much on a par with the Gene speed-wise.
> 
> It is true that the Gene would heat up the beans more by convection than conduction, but much less so that most other air roasters. The air-flow is very low and there are a lot of hot surfaces inside the drum (which is presumably why you get scorching when you dump the beans into a hot chamber).
> 
> But, as you say ... you can lead a horse to water, BUT ...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Cheers
> 
> Robert


Coffee beans are not, nor have they ever been nuts.


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## Batian

Hummmm My fire place does not have a notice saying...

And do read Page 8...

Almonds and cashews are all larger than coffee beans and have considerably more oil weight for weight?

Would I roast coffee in a domestic oven starting from cold? No, of course I wouldn't. The domestic oven is not designed like the Gene and cannot heat up a large space sufficiently quickly....unlike the Gene. It can and hundreds of users have found this to be the case!

If you think the Gene airflow is low and therefore insignificant, hover the palm of your hand over the chaff collector exhaust and see how long you can keep it there. Have due regard to the warning notice on the chaff collector!

And from your baked thread, a link I placed:

https://genecafeusa.com/blogs/news/84044678-how-to-optimize-performance-and-preserve-the-life-of-your-cbr-101-roaster

This was for the American market of the Gene. Say no more!


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## RA5040

ashcroc said:


> Coffee beans are not, nor have they ever been nuts.


Well I think I may be correct in saying that both coffee beans and almonds are 'drupes', technically. Neither are 'nuts', and they are definitely not 'beans' (I think a nut would be something like a wallnut, with a hard outer shell). At any rate, coffee and almonds are not so different ... you could probably make a drinkable coffee from almonds (I think I'll give it a try ... I might start a new craze







).

Robert


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## ashcroc

RA5040 said:


> Well I think I may be correct in saying that both coffee beans and almonds are 'drupes', technically. Neither are 'nuts', and they are definitely not 'beans' (I think a nut would be something like a wallnut, with a hard outer shell). At any rate, coffee and almonds are not so different ... you could probably make a drinkable coffee from almonds (I think I'll give it a try ... I might start a new craze
> 
> 
> 
> 
> 
> 
> 
> ).
> 
> Robert


Apart from the fact walnuts are drupaceous & therfore not botanically a nut either, I'd agree with that.


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## RA5040

Batian said:


> Hummmm My fire place does not have a notice saying...
> 
> And do read Page 8...
> 
> Almonds and cashews are all larger than coffee beans and have considerably more oil weight for weight?
> 
> Would I roast coffee in a domestic oven starting from cold? No, of course I wouldn't. The domestic oven is not designed like the Gene and cannot heat up a large space sufficiently quickly....unlike the Gene. It can and hundreds of users have found this to be the case!
> 
> If you think the Gene airflow is low and therefore insignificant, hover the palm of your hand over the chaff collector exhaust and see how long you can keep it there. Have due regard to the warning notice on the chaff collector!
> 
> And from your baked thread, a link I placed:
> 
> https://genecafeusa.com/blogs/news/84044678-how-to-optimize-performance-and-preserve-the-life-of-your-cbr-101-roaster
> 
> This was for the American market of the Gene. Say no more!


I shouldn't really have mentioned cashews because they are a different category of being. But almonds are the same type of fruit as coffee ... but yes, they are much oiler (about 50% compared to around 10-15% for coffee, I think).

Regarding your link: Of course I don't preheat the Gene without the chamber in place. The whole idea is to heat up the chamber (and the heater parts too). But what you say is "NEVER preheat the roaster without the chamber in place". You don't say "Never preheat the roaster WITH the chamber in place".

You also say: "Your roaster and heating element will last longer if you allow the beans to go through the full cool cycle". Fair enough. But what's the difference (to the machine) between cooling with the beans in the chamber and removing the beans and starting a cooling cycle with the beans out of the chamber a few seconds later? Surely there is no significant difference?

I'm not saying this to be picky. I think it's very important to cool the beans down quickly, otherwise they will keep on cooking ... and with the Gene the only way of doing this is to take the drum out and dump the beans. If there was no way of restarting the cooling cycle I, personally, would put up with a possibly shortened heater life. But there is a very straightforward way of restarting the cooling cycle, so why not do it that way?

Of course, if you prefer to cool your beans with the cooling cycle that's fine ... it's still more or less a free country (I'm talking about the UK not Ireland







).

Cheers

Robert


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## RA5040

ashcroc said:


> Apart from the fact walnuts are drupaceous & therfore not botanically a nut either, I'd agree with that.


That's the problem with nuts ... they only exist in human form


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## Batian

I must correct myself, it is Section 8 on page 15. of the user manual referred to in earlier posts.

In the link above, I was referring to item 4 as well as the whole website to be of the general interest to a Gene user.

Judging the stop point of the roast is all part of the art to allow for the 'cooking on'. There is a rule of thumb.....

however, I now bow to your greater knowledge and experience in using the Gene and feel that steering you towards a better understanding by directing you to the experience of others and using my own more limited knowledge, a total waste of my time.


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## RA5040

Batian said:


> I must correct myself, it is Section 8 on page 15. of the user manual referred to in earlier posts.
> 
> In the link above, I was referring to item 4 as well as the whole website to be of the general interest to a Gene user.
> 
> Judging the stop point of the roast is all part of the art to allow for the 'cooking on'. There is a rule of thumb.....
> 
> however, I now bow to your greater knowledge and experience in using the Gene and feel that steering you towards a better understanding by directing you to the experience of others and using my own more limited knowledge, a total waste of my time.


I don't see anywhere on page 15 where it says not to stop the cooling ... perhaps I'm looking at a different version of the manual?

I am sorry to have upset you. The fact is that I know almost nothing about roasting coffee and I am absolutely sure that you know a million times more than me. But that doesn't prevent me from having some ideas about roasting (which I would be happy to acknowledge are wrong ... as they will most likely turn out to be). As it happens though, I am an engineer (mechanical, electronics and computer, particularly in process control and automation) so I do know a bit about machines ... which is why I'm questioning what is being said about interrupting the cooling cycle. But I don't mean to come across as arrogant.

Anyway this is not really helping to resolve the issue of scorched beans and uneven roast ...


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## ashcroc

RA5040 said:


> I don't see anywhere on page 15 where it says not to stop the cooling ... perhaps I'm looking at a different version of the manual?
> 
> I am sorry to have upset you. The fact is that I know almost nothing about roasting coffee and I am absolutely sure that you know a million times more than me. But that doesn't prevent me from having some ideas about roasting (which I would be happy to acknowledge are wrong ... as they will most likely turn out to be). As it happens though, I am an engineer (mechanical, electronics and computer, particularly in process control and automation) so I do know a bit about machines ... which is why I'm questioning what is being said about interrupting the cooling cycle. But I don't mean to come across as arrogant.
> 
> Anyway this is not really helping to resolve the issue of scorched beans and uneven roast ...


Back when I repaired white goods, I had countless callous to washer dryers that had popped the thermal fuse on the dryer heater due to it's cooling cycle being interrupted.

Just because the power has stopped going to the element doesn't mean it's immediately cooled down. It needs the fans running to help stop it overheating.


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## RA5040

ashcroc said:


> Back when I repaired white goods, I had countless callous to washer dryers that had popped the thermal fuse on the dryer heater due to it's cooling cycle being interrupted.
> 
> Just because the power has stopped going to the element doesn't mean it's immediately cooled down. It needs the fans running to help stop it overheating.


That's fair enough ... it probably is better to cool down the element with the fan running.

What I do is to run the Cool cycle for about 30 seconds (which should be way longer than necessary to cool down the element) and I then emergency stop. I dump the beans, put the drum back in and restart the cooling cycle.

Can you see anything in this procedure that would be damaging to the machine?

Cheers

Robert


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## MediumRoastSteam

johnealey said:


> ^was what I was trying to explain much earlier about behind the screen and although it may not seem like a lot it does seem to affect the airflow over time. You may also want to vacuum the underside of below the controls as there is a fine mesh filter behind here that can also get gummed up with dust / fluff.
> 
> If all works well once above done then ignore the more recent advice re centre flappy thing rings, if not go ahead and spend the £12 plus postage on a spare one.
> 
> John


Just a quick update:

Today I was roasting with the chaff collector in place. I can't still hear first crack in time (by the time I hear it, I think it's already rolling). Anyhow, as I was roasting, towards FC and during I noticed accumulation of chaff in the chamber exit. So I thought gravity may help, and I tilted the Gene slightly and the flappy thingy then wiped the chaff out. I actually thought that the Gene might be unlevelled, but a quick check with the spirit level proved me wrong... So you may be right: I need a new chamber divider from BB. I don't know how it could've got damaged though, but £12 won't hurt. My Gene is also still under warranty.


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## MediumRoastSteam

Another update: I just roasted some beans after a while. Indoors, chaff collector in place and a duct to take smoke out through the window. And no chaff accumulating inside the chamber. And this proves they I found what was going wrong inside the chamber and chaff was accumulating around the chaff cutter thingy.

Basically, when washing the chamber, I must have pressed a little hard around the exit grate, effectively flattening it around the middle, to the point that the cutter was not actually touching the grate to wipe the chaff away, hence the accumulation. I have since applied some pressure on that grate - effectively bending it just slightly so the whole thing is now slightly angled and curved, and no chaff is getting trapped.

Progress at last!


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## filthynines

@MediumRoastSteam Time to resurrect an old thread! What progress did you experience with your roasts when you removed the chaff-trap problem?


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## MediumRoastSteam

filthynines said:


> @MediumRoastSteam Time to resurrect an old thread! What progress did you experience with your roasts when you removed the chaff-trap problem?


Hi - I've sold the Gene a while ago. The biggest improvement was that I could hear first crack very clearly.


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## filthynines

Thanks MRS - did solve your scorching problem? And could you hear first crack without stethoscope?


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## MediumRoastSteam

filthynines said:


> Thanks MRS - did solve your scorching problem? And could you hear first crack without stethoscope?


I never really managed to hear first crack with a kitchen roll tube, stethoscope (medical or mechanical). The only time I could hear it was when I took the chaff collector off. One of the reasons I sold in the end as it proved hard for me to roast indoors.

I think the scorching was more related to the post above where the "thingy" was stuck and not freely moving. I think removing the chaff collector also helped with that, but I'm not sure.

Sorry I can't be of much help.


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## filthynines

No, that's very helpful, thanks very much


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