Egholm Senior Member Joined: 24 Oct 2007 Posts: 55 Location: Denmark Expertise: I love coffee
Roaster: iRoast2
Posted Sun Nov 25, 2007, 2:51am Subject: Light roasts on an iRoast2? FC after 4-5 minutes...
Hi there,
All this talk about lighter roasts triggered this one: How many of you are doing (good) lighter roasts on the iR2?
I've mod'ed mine with a 2k7, but still I can't seem to extend FC beyond 5 minutes - and nothing like 7-8 minutes "prescribed" in http://www.bootcoffee.com/ROAST3.pdf. So I tend to cool my beans after 7 minutes, already, but I think they turn out a bit sour (maybe I'm brewing them wrong?)... When I did them in my oven, FC wasn't until 9-10 minutes, and pulling them at 11-12 made them taste fantastic - however, this is a couple of months ago, and maybe I'm just better at tasting now?!
I'm considering starting the roast with the top lid off for a couple of minutes, but just writing the idea out makes it sound kinda crazy :-)
Posted Sun Nov 25, 2007, 9:50am Subject: Re: Light roasts on an iRoast2? FC after 4-5 minutes...
I don't see where Mr. Boot prescribes a 7-8 minute light roast in that article. His example points more towards a 10-11 minute total roast time. In one of his roasting articles he sets some general guidelines that roasts should be no shorter than 8 minutes and not longer than 15. (I believe that was for a sample roaster) 5 minutes is too short to develop the roast for sure.
Egholm Senior Member Joined: 24 Oct 2007 Posts: 55 Location: Denmark Expertise: I love coffee
Roaster: iRoast2
Posted Sun Nov 25, 2007, 10:08am Subject: Re: Light roasts on an iRoast2? FC after 4-5 minutes...
Frost Said:
I don't see where Mr. Boot prescribes a 7-8 minute light roast in that article. His example points more towards a 10-11 minute total roast time. In one of his roasting articles he sets some general guidelines that roasts should be no shorter than 8 minutes and not longer than 15. (I believe that was for a sample roaster) 5 minutes is too short to develop the roast for sure.
Sure, the 7-8 is what it takes for him to reach FC - at least according to the graph... And yes, 10-11 minutes total; whereas I need stopping at around 7 minutes for a (visually) light roast...
Posted Sun Nov 25, 2007, 10:17am Subject: Re: Light roasts on an iRoast2? FC after 4-5 minutes...
Ahhh, I get confused with these 2 letter acronyms: FC can mean 'Full City' or 'First Crack' around here, depending on context. Which sometimes is still not clear. Got it.
Egholm Senior Member Joined: 24 Oct 2007 Posts: 55 Location: Denmark Expertise: I love coffee
Roaster: iRoast2
Posted Sun Nov 25, 2007, 11:26am Subject: Re: Light roasts on an iRoast2? FC after 4-5 minutes...
Frost Said:
Ahhh, I get confused with these 2 letter acronyms: FC can mean 'Full City' or 'First Crack' around here, depending on context. Which sometimes is still not clear. Got it.
hazbean Senior Member Joined: 21 May 2007 Posts: 15 Location: Adelaide, SA, Australia Expertise: I like coffee
Espresso: Isomac Mondiale Grinder: Mazzer Mini E, Gaggia MDF Vac Pot: Santos Roaster: Gene Cafe
Posted Sun Nov 25, 2007, 11:53pm Subject: Re: Light roasts on an iRoast2? FC after 4-5 minutes...
" ... still I can't seem to extend FC beyond 5 minutes"
That seems odd. With a modified iR2, I usually have first crack between six and seven minutes. Without the mod, often past FC at three minutes :(
I know 2k7 is on the high side already, but maybe you need it even higher. I did some experiments with a potentiometer set to various values, then hard wired a resistor of what seemed the best value (2k7 in fact).
Egholm Senior Member Joined: 24 Oct 2007 Posts: 55 Location: Denmark Expertise: I love coffee
Roaster: iRoast2
Posted Mon Nov 26, 2007, 1:18am Subject: Re: Light roasts on an iRoast2? FC after 4-5 minutes...
hazbean Said:
" ... still I can't seem to extend FC beyond 5 minutes"
That seems odd. With a modified iR2, I usually have first crack between six and seven minutes. Without the mod, often past FC at three minutes :(
I know 2k7 is on the high side already, but maybe you need it even higher. I did some experiments with a potentiometer set to various values, then hard wired a resistor of what seemed the best value (2k7 in fact).
Hmm... That may be the reason! I never tried any higher - I read about 2k being the most often used one, then I saw somebody using 2k7 (maybe you), and settled with that one... For the fun of it, I could try even higher! However, it's not like it ever goes down in fan-speed when running at 320F (after the initial transient where running with lower fan-speed)... But maybe there is a fan speed even faster than what it settles on now for 320F... I should try that!
hazbean Senior Member Joined: 21 May 2007 Posts: 15 Location: Adelaide, SA, Australia Expertise: I like coffee
Espresso: Isomac Mondiale Grinder: Mazzer Mini E, Gaggia MDF Vac Pot: Santos Roaster: Gene Cafe
Posted Mon Nov 26, 2007, 2:26am Subject: Re: Light roasts on an iRoast2? FC after 4-5 minutes...
Egholm, I'm not entirely convinced that fan speed is the only variable used by the iR2 in trying to keep to a profile. In fact, even when I set a lowest temp possible profile of 160C/15mins, the fan varies occasionally even after the first couple of minutes. I've run it with the chamber off, looking directly at the heating elements, and noticed variation in both intensity and how many of them are active. The fan / element control system is a deep mystery :(
I read somewhere that the range of settings for the resistor was 1 to 5k. In another iR2, I was using 1k8, and was a bit surprised to have this come in 2k7. Our voltage is still 242-244V pretty consistently. I think there is a fair bit of manufacturing variation. I'm surprised actually that you need to set the resistor so high -- my iR2 the 230V version, as I'm sure yours is, but I doubt that your line voltage would be as high as 242V.
Egholm Senior Member Joined: 24 Oct 2007 Posts: 55 Location: Denmark Expertise: I love coffee
Roaster: iRoast2
Posted Mon Nov 26, 2007, 2:33am Subject: Re: Light roasts on an iRoast2? FC after 4-5 minutes...
hazbean Said:
Egholm, I'm not entirely convinced that fan speed is the only variable used by the iR2 in trying to keep to a profile. In fact, even when I set a lowest temp possible profile of 160C/15mins, the fan varies occasionally even after the first couple of minutes. I've run it with the chamber off, looking directly at the heating elements, and noticed variation in both intensity and how many of them are active. The fan / element control system is a deep mystery :(
I read somewhere that the range of settings for the resistor was 1 to 5k. In another iR2, I was using 1k8, and was a bit surprised to have this come in 2k7. Our voltage is still 242-244V pretty consistently. I think there is a fair bit of manufacturing variation. I'm surprised actually that you need to set the resistor so high -- my iR2 the 230V version, as I'm sure yours is, but I doubt that your line voltage would be as high as 242V.
Ahaa, I thought the fan was the only one... This being the fact, suggests that I should try with the higher resistor... And you're right about the 230V - as I recall it, I actually measured it to 231V - but that was 3 years ago... I'll try again tonight! But still, as you state, there is a bit of "manufacturing variation" - so that may explain it?!
When does 1 crack occur when running 160C/15mins (320F for you non standard guys)? How does the bean taste with such profile?
hazbean Senior Member Joined: 21 May 2007 Posts: 15 Location: Adelaide, SA, Australia Expertise: I like coffee
Espresso: Isomac Mondiale Grinder: Mazzer Mini E, Gaggia MDF Vac Pot: Santos Roaster: Gene Cafe
Posted Mon Nov 26, 2007, 2:51am Subject: Re: Light roasts on an iRoast2? FC after 4-5 minutes...
That profile I did almost entirely for experimental purposes :) The one batch I remember was OK, but it was a bean that I hadn't much experience with. It's not a good profile because it maximizes the time to reach FC; because the iR2 reaches 160-170C fairly quickly regardless of setting, the effect is to prolong the time between drying and first crack, which most people agree is not a good thing.
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