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Thread: advice needed on hottop roaster

  1. #1
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    advice needed on hottop roaster

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi all
    I have recently bought a hottop B roaster and done my roasting a few times with it
    but I think I am having trouble with temperature control of my roast
    Like my last batch of 250g ended up reaching 220c too early which is the maximum temperature set by the roaster and got ejected by the machine
    I was trying to roast the batch a few second into second crack but the bean did not look dark enough
    They looked like city ~ city+ and the display temperature got to 220C a bit too early and it seems like bean mass temperature do not catch up with the air temperature of
    the drum ( assuming that air temperature is the one shown on display )

    I dropped the bean after preheat at 75c(full heating, no fan) and dropped the temperature by like 60% heating, 25% fan when first crack was heard, let it coast to second crack slowly with 30% heating, 25% fan. At around 211C ejected.

    Result: still look like a bit under roasted( looked like CS 7~8 where I am aiming for CS 9ish)

    As a newbie to home roasting, any help regarding temperature control would be greatly appreciated

    Thank you

  2. #2
    enjoy black coffee JamesM's Avatar
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    do you recall at what time you hit first crack and second crack? and may I ask which bean you are roasting?

    cheers

  3. #3
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    Hi
    I used guatemala organic single origin sourced from ministry grounds
    I hit first crack at around 10:45 and ejected at 12:55 which was the beginning of second crack

  4. #4
    Senior Member insomnispresso's Avatar
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    That is a very fast roast for the hottop!

    2mins between cracks sounds like the roast didn't slow down much, I usually drop heat to 50% and fan max approaching first crack to slow the rise of rate enough. Hard to measure without a DMM (which you should use!) but I am trying to hit R1C (or end of first crack) with a rate of rise of 3-8 deg which will let you get the 3-5 mins between cracks you'd want.

    The fan helps empty heat in the drum so that may be the one part your missing, of course be careful not to stall but its hard without a DMM

    Hope it helps!

    Cheers
    Matt

  5. #5
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    Thank you for your reply matt!!
    i will try what you told me
    Btw, how can i go about that DMM? Can i do it like DIY?
    If that helps give me better control of my roast, im willing to do it!!

  6. #6
    Senior Member insomnispresso's Avatar
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    There are some posts around te Internet about this, I found what worked for me was to fashion a wooden block which sits in the bean entry shoot and drill a whole through for the DMM

    You can get the DMM from here in BeanBay! And that will work with the RoastMonitor software which you can also get from this site. If you have trouble finding I just let us know!

  7. #7
    enjoy black coffee JamesM's Avatar
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    I was going to chime in but Matt nailed it. you need to slow that roast by reducing heat and adding fan without stalling it. There is a lot of info, including profiles to be found for hottop, but of course, every bean is different!

  8. #8
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    You need to reduce the temperature BEFORE you get to 1st crack. When roasting for espresso, I can stretch the time between 1st and 2nd crack to 4 minutes. I drop the heat to 60% when my Hottop display temp gets to 350 F.

    I posted some of my recent Hottop profiles in this thread: http://coffeesnobs.com.au/roasters/3...tml#post486077. One of them is for a roast of some Guatemala El Injerto. I was roasting for drip coffee, so I did not roast this bean up to second crack.

  9. #9
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    Be prepared for a few failures. I found learning to roast took quite a while. The hottop's were fairly new then and there wasnt the experience to draw on that currently exists.
    My roasting profile is fairly simple and doesn't vary a lot between beans. I aim for maximum rate of temp increase intil a bean temp of about 150 deg then progressively slow the rate of temp increase down to 6 - 7 deg per minute by the time of first crack. (that is one degree per 10 seconds, I do a fair bit of counting during the second half of a roast ) Hold the rate of temp increase at about 6 deg per minute beyond that. I put the fan on low setting at 100 deg and rarely adjust it. I do this to keep a bit of air moving through the drum to remove smoke. I try to reduce the heat leading up to first crack so there is enough internal heat so the roast doesn't stall and the beans won't need a blast of cool air to slow them down.
    As a starting point leave the roaster on full heat until the bean probe temp reaches 155 deg, then reduce to 8 and at 165 reduce to 7. Leave at 7 until well into first crack and then drop back to 5. Generally leave at 5 until finish of roast.
    Some beans are prone to stall at the start of first crack and that is an experience thing. Once they have past the stall the rate of temp increase will tend to race away. Watch the rate of temp increase during first crack and as soon as it starts to increase drop the heat back to 5 Some beans will give a similar stall approaching second crack.
    I generally work with one to two kg lots of green beans as it can take a one or two roasts to get the profile right for a new batch of beans and it also can take a few shots to get the grinder dialled in.
    I haven't got into recording or monitoring roast profiles electronically but have come back to coffe snobs to see what other roasters are doing and if I can tweek my roasting process.
    nickm likes this.

  10. #10
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    Behmor Coffee Roaster
    Good advice from Tony and rgrosz.
    I came to my hottop from a behmor that died an honorable death from overuse.
    It has taken a while to get where I am consistent in the roast levels and it remains to be seen how I cope with winter where I struggled to get consistency with the Behmor.
    I roast 300g at a time using the controls much as Tony does above
    If I feel the temp is getting away from me I also lift the filter to improve the cooling closer to the cracks , being careful not to stall.
    I use a temp probe through the bean shute.
    start of first crack is pretty consistently within a 5 degree or so variation between beans
    I now drop in a 1-2 degree difference at 2nd crack and I am happy with the results.
    This has helped me a lot with beans of variable size such as some of the ethiopians where I also find it hard to hear the second crack reliably
    I also tend to do 4 roasts back to back and use the roast monitor software to try and get similar (though not identical)profiles
    Hope this helps
    Last edited by lakeman; 21st December 2012 at 12:02 AM. Reason: spelling



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