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  • GrahamK
    replied
    Re: First Crack time

    Hi Summercrema,

    Not sure if it will be helpful and if you use the CS USB Monitor software, but if you do I have attached a template I use for quite a few beans which shows the Hottop changes I make at each point. My Hottop program (in this case saved in AD2), follows these adjustments, and it seems to work pretty well generally. F1-F4 are the Fan adjustments, xx% are the heat adjustments. A1=180deg, A2=210deg alarms or roughly when you can expect them to go off. The Load, first crack, RFC, second crack, RSC and Unload are also all notated. I allow the Hottop to follow the saved program until 1st crack then I manually adjust to suit the circumstances. Usually in fact I drop the temp to 30% immediately after first crack then adjust it up as required and to prevent stalling etc.

    So I load the template to show what the saved program is doing and as a guide.

    It is set for a 250g batch.

    Graham

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  • summercrema
    replied
    Re: First Crack time

    pardon me, 2 to 3 degrees per minute should be.

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  • shawty
    replied
    Re: First Crack time

    Originally posted by 5D5B43434B5C4D5C4B434F2E0 link=1280724741/4#4 date=1283126814
    2 to 3 degree rises every sec
    So this made second crack at about 1237ºC  

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  • summercrema
    replied
    Re: First Crack time

    after two more try with the Kenya Kagunyu AA I think I got the idea how to roast it properly, this time unloaded the beans at 213 degree, FC happened at 187 degree from then on 2 to 3 degree rises every sec, FC to SC took 7 minutes, unload 15 sec. into SC. Tasted it after 5 days later, good with or without milk but mostly latte I make. Thanks Andy for the beans, thanks Greg for a good machine, thanks Mal & Beabeabeaner for the links, now I dont have to put up with terrible coffee in Westfield food court.

    One thing interesting though, is that having both Panel & DMM temp displayed in front of me I can see when the Panel Temp slowed to a stall the DMM still rising slowly, I wonder where are the heat sensors located in the machine, must be different places in the roaster?

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  • pullman
    replied
    Re: First Crack time

    Hi Summercrema,

    The temperature at which a given bean cracks is about the same, so in short no you cant really change the temperature at which a bean cracks. What you CAN control is how long it takes to get to that temperature.

    Most of my profiles start with full power, drop to about 70% between 3 and 5 minutes with some fan (drying stage), then back up to full power; I normally drop back to about 70% just before FC and then 50% after FC. This slows the heating into a slow gentle ramp of a few degrees per minute. You can get more accuracy with a bean mass probe and drop this down to 1-2 with care.

    The Auto program is a waste of time in my opinion; its a very basic program and is very smokey because it doesnt make much use of the fan. Good I guess if you dont know where to start and just want to watch it do its thing, but with all our roasters we supply that sample program so that shouldnt be necessary. Ive used it once if that says anything :

    Id also say to increase your batch size to 250g if youre struggling getting the hang of the thing; thats the optimal size and while Ive roasted between 100 and 500g on my unit (and voided my warranty with the second figure there) it does require a closer watching of whats happening - with a small batch the heat can get away from you very quickly, with a large batch it takes a lot longer for program changes to take effect so again you can get caught out.

    Take a look at Randys guide on roasting with the B http://hottopusa.com/profile.pdf When we started there was nothing around like this but its an excellent resource for seeing what to do and why you should do it. My temperatures are a bit different to his but the basic elements are the same. Also you obviously have to convert F to C.

    The Hottop B allows excellent manual control so its all in the data you as the operator put into it

    Greg

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  • beabeabeaner
    replied
    Re: First Crack time

    I have been at it for about 18 months in the hottop B.
    It seems that first crack always happens at the same temp for a particular bean. Much easier to appreciate with a temp probe/DMM installed.
    I tend to set the 3 programs according to bean density - I use the AD1 for hard beans e.g ethiopians, AD2 for indonesian and central americans, AD 3 for low altitude coffees like Kona, Jamaica and Mountain Top. The main difference is how much heat in the early part of the roast, decreasing through these presets - the AD1 is pretty much full power, AD2 drops to 7-8 after a few minutes and increases temporarily towards FC, and AD 3 stays about 7 from the start.
    Roughly, anyway.
    Once I get a feel for when Fc occurs I drop the heat to 2-4 about 1-2 minutes before it happens, then increase it again to around 7 a couple of min later while FC is still going - this is to avoid stalling after FC, but you will need DMM to appreciate this!
    Fan can be used to finetune temp control but I generally start it and turn it up when smoke appears/reappears. I find this is better controlled for each roast as fan efficiency is affected by state of the rear filter.
    My tip is go and read the hottop roasting tips in the HOW TO pages of espresso!myespreso! website - http://www.espressomyespresso.com/

    I nearly always roast 250g and fiddle the other variables.

    The Kenya Kigunyu is probably my best so far. Try it with the AD1 or 2 profiles described above and go just past start of SC, then rest 1 week.

    To get a better feel for it, get a thermocouple. I really improved with this. I drilled a hole (actually 2 holes, got it right eventually!) at the back and popped the probe into the bean mass.

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  • Dimal
    replied
    Re: First Crack time

    Some excellent info about this sort of thing can be found pinned up above s_c....

    http://coffeesnobs.com.au/YaBB.pl?num=1280212804

    Mal.

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  • summercrema
    started a topic First Crack time

    First Crack time

    I have my HT KN8828B delivered to me three weeks ago, so far done five batches of Kenya Kagunyu AA, batch size is 150g each time, the last four roasts didnt come out right I stopped too early somewhere during rolling FC end up quite acidic, beans color cs7, this morning I tried again I waited until rolling Second Crack with bean color cs 9-10, fair bit of smoke but not as much as when roasted with AUTO setting.
    I know I can keep the temp rising slowly between FC & SC by changing the FAN & HEAT POWER, but is there any benefit in varying the FC & SC temperature? May be I should ask is it possible to change FC & SC temperature?
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