Roasting with a Turbo Crazy

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Roasting with a Turbo Crazy

Postby bronc » Tue Mar 19, 2013 8:04 pm

So I finally assembled my Turbo Crazy and tried roasting today. Here are the results - http://imgur.com/a/gcYN6 I don't like the results very much, to be honest. The first crack started after around 10mins so I decreased the temperature to ~180*C and I think that this stopped the crack from continuing because I just didn't hear it any more. I stopped the beans at the 17th minute.

Starting weight - ~180g
Ending weight - ~150g
Change - ~16-17%

I ordered a digital thermometer today and it should be here by Thursday. I'm guessing that the thermostat of the convection oven is way off and this is causing my troubles. I'm a bit worried about not hearing a strong first crack and also that there is quite a lot of chaff still attached to the beans. What do you think?

Can you recommend me something like a roast profile? Not really a roast profile but more like what temperature to aim for at what time. For example, 220C until I hit first crack, then decrease it to 180C during the crack to stretch it out, then up it to 240C until I hear 2nd crack. Something like that, just a guideline.. :) Thanks!!
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Postby simonp » Tue Mar 19, 2013 11:59 pm

It sounds and looks like the roast stalled which would mean you dropped the heat too low. Looking around it looks like 10 minutes to 1st is about normal with that roast method so it can't be far off. At this stage it is all about experimenting, so try a roast without dropping the heat and see how soon after 1st crack you get to second, this will give you some idea as to how much you need to drop the heat.
You say you dropped the heat to 180C during 1st crack but don't mention turning it up again. Bearing in mind that 2nd crack needs the beans to be at 212C once the exothermic bit in 1st crack is done you need the environment temperature to be higher than 180C to get the beans to 212C. Back the heat off a bit during 1st but wind it up again after to finish the roast or get to 2nd crack.

To make things easier use your digital thermometer to get into the bean mass as this is the best indicator of what is going on. You never want the bean temp to drop (disregarding short glitches) or to stall for long.
In general you don't want around 4 or so minutes between 1st and 2nd crack (if you go that far). 10 minutes to 1st and a 13-14 minute total roast time is reasonable with an air roast.

Have you tried the beans? You may find that they taste fine, you obviously went into first crack so they shouldn't be too bad.

Look at the example log of a roast I did, red line is the chamber temperature, blue line is the bean mass temp. The mean mass temp reads a little high, but close enough to give you an idea.
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Postby bronc » Wed Mar 20, 2013 6:42 am

Thanks for the post! It is really helpful. I'm just trying the beans in a French press.. They just taste a bit bitter and nothing more :o I think they just taste a bit grassy.

I really didn't think about having to up the temperature after the 1C but that's the first time I've actually had any control on my roast (and I messed it up). My thermometer should be here tomorrow and I'll try it out again. I think most of the beans didn't even go through 1C because when I grind them the inside of my Hario becomes full of a chaff-like material.

Thanks for the graph, I'll check it out. Any chance you could upload a bigger version because this one is a bit hard to read :roll:
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Postby CakeBoy » Wed Mar 20, 2013 8:28 am

GB and Simon are better qualified to advise you but grassy generally equates to under-roasted, suggesting it did indeed stall when you reduced the temperature around first crack, never reached second effectively ending the roast and the beans then just baked on for the remaining seven minutes.
Last edited by CakeBoy on Wed Mar 20, 2013 10:02 am, edited 1 time in total.
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Postby GreenBean » Wed Mar 20, 2013 9:59 am

Further to what Simon and Cakey have already said I would suggest that you do not get too hung up on the actual temperatures you are reading. The readings will depend on many factors and in particular where and how you are taking the readings. Provided the readings you are getting are consistent from roast to roast the important thing is to experiment and note the temperature you read when first crack and second crack occur. As Simon has suggested a bean mass temperature reading would be best.

You should then experiment at reducing the heat before you reach the indicated first crack temperature (say one minute before) by just enough to slow the roast to between 3.5 and 4 minutes from first crack start to end of the roast. If you reduce the heat by more than this you will be in danger of stalling the roast.

You should be aiming for a bean mass temperature profile of something like that in the chart Simon has provided above. In my Hottops I use a profile such as the following:

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Postby bronc » Wed Mar 20, 2013 10:04 am

Yes, that sounds very plausible. Just received my thermometer so if I have the time today I'll try to roast a batch of Brazil Daterra Bourbon.

Wow, thanks, GB!
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Postby simonp » Wed Mar 20, 2013 10:16 am

bronc wrote:that's the first time I've actually had any control on my roast (and I messed it up)


As did we all early on :)

GB's graph is better as his measurment points are much better optimised than mine so use that as a guide.
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Postby bronc » Wed Mar 20, 2013 11:47 am

Well, here goes nothing.

In: 160
Out: 133
Change: 17%

Start of 1C: 10:30min
Temperature 1C: 240*C (according to the thermometer which was just above the beans, slight touching them from time to time :roll:)
End of 1C time: ????min
Start of 2C: ????min
End time: 16:30min

Here are some photos of the beans:
http://imgur.com/a/Xjr7x

Looks like a Vienna roast? :( I was aiming for FC.

There are dents and small holes on a number of beans which as far as I know is a sign of 2nd crack. I think I should have stopped earlier. Next time I think I'm just going to but the temperature to 220* during for the first 9-10mins, then decrease it to 200~ to stretch the crack until let's say the 12-13th minute and then up it to 220-240*.

I have a hard time hearing the cracks I guess. Which one should be louder? First or second?
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Postby simonp » Wed Mar 20, 2013 12:40 pm

Unless the photo colour is fooling me, they don't look massively dark. Yes holes will mean 2nd crack and also going into it quite fast. 1st crack it the loudest, like breaking a pencil, 2nd is more a crackle like Rice Crispies in milk! Some beans have much louder cracks than others. It will take time to tune your ears in and is harder using loud roasters.

At least you know what happens whne you blast it now and you know that the setup will roast to 2nd crack. It is a little like firing stradling shots accross a ship to judge distance I guess.

Your plan sounds good to me, from your previous experiences I would say that will get you somewhere close.
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Postby bronc » Thu Mar 21, 2013 12:20 pm

Tried them today but couldn't dial them in. :? 9 clicks on my Tiamo - 20-25ml in about 35-40sec.. too slow. 10 clicks - 40-50ml in 15-20sec :lol: Anyways, I'll let them rest a bit more and try them again tomorrow because I try to limit myself to two espresso a day.
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Postby bronc » Sun Mar 24, 2013 9:28 am

Is it possible to reach 2C without passing through 1C? :o Those Brazilian beans are awful for home roasting :(
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Postby bruceb » Sun Mar 24, 2013 9:56 am

bronc wrote:IThose Brazilian beans are awful for home roasting :(

I think there are a lot of home roasters that would consider those to be fighting words. 8)
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Postby bronc » Sun Mar 24, 2013 10:19 am

Haha :lol: But really, there is almost no distinction and time between first and second crack with those beans..
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Postby CakeBoy » Sun Mar 24, 2013 11:23 am

Real men eat them green and wrestle with Robusta producers ;) :)

No, you defiately have to reach first crack before second. Either you are reaching both and not hearing one, possibly they are very close together, or you are only reachng first.

Have you heard the different cracking at all, first like Rice Krispies and second like snapping twigs?
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Postby bronc » Sun Mar 24, 2013 12:59 pm

I'm pretty sure I heard a few 1C but just a few then nothing and then I started hearing what I think was a 2C plus the beans started smoking, becoming pretty dark and oil appeared.
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