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Thread: Behmor Roasted PNG Waghi AA CS8

  1. #1
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    Behmor Roasted PNG Waghi AA CS8

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hey guys,

    I just invested in a $30 drill from Bunnings and made a hole in my Behmor according to Andys template.

    After piercing the probe into the roaster, I pre-heated the roaster for 1.5 minutes. I noticed from the corner of my eye, the DMM recorded up to 130C. How is that possible all within a space of 1.5 minutes from a cold machine? Is the probe faulty?

    I closed an eye and decided to fill the basket with 207g of PNG Waghi AA green beans that I just received last week from BeanBay.

    I managed to roast it CS8 this evening, and used Intellidepths sexy Excel charting tool to come up with the attached graph. As you can see, the DMM recorded a peak of 267.7C at the 11th minute. I always thought the machine would go at max to about 240C or so.

    The graph, as you can see, seems pretty sketchy. Is this to be expected?

    Now, as part of my learning experience, with this graph in place (assuming no problems with the probe), how can I use it as my template for my next roast? I stopped the machine at the first sound of the 2nd crack. Does that mean I should learn to stop just before second crack in the future?

    Forgive me for being a n00b. Thanks again for your help.

    See you guys at Beanology Sydney!!!


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    Re: Behmor Roasted PNG Waghi AA CS8

    Anyone? :(

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    Re: Behmor Roasted PNG Waghi AA CS8

    Something strange there, I guess its because the probe is measuring environmental temp rather than bean temp. as second crack occurs at around 220[ch8451] give or take - so hitting such a high temp at first crack is odd.

    I reckon the graphs and temps are largely distracting anyway, if you are hitting first crack at just over 11 minutes then you are in the ball park, to me the gap between 1st and second is far too long, nearly 8 minutes, in fact i suspect you stalled the roast there.

    See if you can get to 2nd crack 4 minutes or so after 1st crack, cool to room temp as fast as you can and see how it tastes in the cup!

    Thats a good starting point regardless of what the graph looks like.

    Where you stop the roast is personal preference, the trend in so called 3rd wave cafes is to very light roasts, stopped before 2nd crack. I much prefer the flavours brought out by roasting just into second crack, but thats just me.

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    Senior Member brettreaby's Avatar
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    Re: Behmor Roasted PNG Waghi AA CS8

    I get similar graphs to this, and am convinced behmor logic is faulty ( I reckon the dip is far too great before main heater kicks in again) but got told I was soooooo wrong....

    Anyway there is a way to. Improve it as follows:
    1. Use p2. Behmor delivers most heat at this setting I have found through measurements.
    2. You can increase the heat applied after the afterburner comes on ( around 10 minute mark) by setting voltage to 220v. This increases the voltage on the afterburner from 188vac when it comes on to 240vac. It doesnt harm the machine, just the afterburner heater delivers more power and the temp dip after it comes on is way less.
    3. I also crack the door after c1 so can keep a close look at the roast.
    4. It would be great if the behmor instruction actually told you what its doing: it doesnt so totally ignore the p1,2,3,4,5 graphs in the manual.

    (not 100% certain of this but by some tests) I also found that the time setting adjustment only extends or shortens the end of the roast: basically the main heater comes on for the first stage and the afterburner kicks in at a set time. Changing the roast time from there just extends or truncated the time till cooling cycle..

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    Senior Member brettreaby's Avatar
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    Re: Behmor Roasted PNG Waghi AA CS8

    Btw I am using an environmental probe top left of the unit.

    Of course a bean probe would be better but not easy: I tried to drill out the hub of the drum left hand end to insert a probe but the material is hardened. Short of removing and making up a new mild steel hub I cannot find a way to get a bean probe in there. And even if the center hub idea worked you wouldnt be in the beans.

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    Re: Behmor Roasted PNG Waghi AA CS8

    Quote Originally Posted by 6E7E6978787E696D6E750C0 link=1331550786/3#3 date=1331674738
    You can increase the heat applied after the afterburner comes on ( around 10 minute mark)* by setting voltage to 220v. This increases the voltage on the afterburner from 188vac when it comes on to 240vac
    Hey Brettly - how do we increase the heat by changing the voltage? Is there a dial that we can turn on the side panel (after removing the side covers)?

    I have always wanted to learn how to manually increase the heat (bypassing the profile setting). I had the assumption the safest was to use P1 profile at the early stage of the roast, and then open the door to lower the roast temperature.

    Quote Originally Posted by 6B6D6079616D750C0 link=1331550786/2#2 date=1331640580
    I guess its because the probe is measuring environmental temp rather than bean temp
    Hey galumay - how can we ensure the probe measures the bean temperature? I would expect this to be pretty consistent across all Behmor users since the hole drilled is in accordance to Andys template.

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    Re: Behmor Roasted PNG Waghi AA CS8

    Darryl, I dont think you can. I forgot that was how they are setup on the Behmor. Not sure it really matters anyway, first crack is first crack - regardless of what temp your thermocouple displays. It still allows you to compare profiles regarding timing of first & second crack which is the main thing.

    I come back to the point that the main issue I see with that profile is too long between cracks.

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    Re: Behmor Roasted PNG Waghi AA CS8

    Quote Originally Posted by 35333E273F332B520 link=1331550786/6#6 date=1331722584
    I come back to the point that the main issue I see with that profile is too long between cracks.
    Will there be an improvement in flavors if I leave the door open for a lesser time? What should I be looking out for in terms of flavors?

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    Re: Behmor Roasted PNG Waghi AA CS8

    Quote Originally Posted by 62667D770F0 link=1331550786/5#5 date=1331715893
    Hey Brettly - how do we increase the heat by changing the voltage? Is there a dial that we can turn on the side panel (after removing the side covers)?

    I have always wanted to learn how to manually increase the heat (bypassing the profile setting). I had the assumption the safest was to use P1 profile at the early stage of the roast, and then open the door to lower the roast temperature.
    Well you arent really bypassing anything, but what is happening when you set the voltage to 220 is the behmor appies the full 240VAC to the afterburner heater rather than 188VAC)- increasing afterburner power by about 100W i reckon.

    When the afterburner fan comes on it tends to cool the air temp and the afterburner heater compenates for this.* by using 220v setting ( turn unit on holding A button) you apply more heat at this stage and temp doesnt drop as much.

    This makes for a shorter time to second crack and the ET doesnt plummet.

    I have also fitted a switchable 80k resistor in line with a the afterburner thermistor: this allows me to restart the roast any time i like even if machine is hot. BUT if you plan to do this you should use high temp silicon cable the this area and good luck with your warranty!

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    Re: Behmor Roasted PNG Waghi AA CS8

    Quote Originally Posted by 7E6E7968686E797D7E651C0 link=1331550786/8#8 date=1331781195
    I have also fitted a switchable 80k resistor in line with a the afterburner thermistor
    Dude youre insane! I wish I had that sort of skills to tweak the roaster. It was indeed refreshing to hear your thoughts. I held on to the A button today, and made a fresh batch of Ethiopian Limmu. I think the heat was pretty intense that second crack almost came immediately after first crack. I didnt know when it was but when I saw then beans, it was already pretty dark and thought I should really stop.

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    Re: Behmor Roasted PNG Waghi AA CS8

    Quote Originally Posted by 37313C253D3129500 link=1331550786/2#2 date=1331640580
    Something strange there, I guess its because the probe is measuring environmental temp rather than bean temp. as second crack occurs at around 220[ch8451] give or take - so hitting such a high temp at first crack is odd.
    I think I found out the reason for this - the fabric sheath at the connector end (to the DMM) has a little tear. When I press on it with my fingers, the temperature jumped up by about 30 degrees. I will probably need to take it to Jaycar to have it looked at. Unless you think its not the real reason for it?

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    Senior Member brettreaby's Avatar
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    Re: Behmor Roasted PNG Waghi AA CS8

    The sheath wouldnt be doing anything, more likely you have a loose connection in the cable or even inside the multimeter: check over as best you can, maybe go to jay car and plug in a thermocouple and wiggle the connectors: if you get the problem again it might be the multimeter and not the thermocouple.

    Note: unplug the thermocouple altogther and you should get a reading close to the ambient temperature.


    Quote Originally Posted by 7D796268100 link=1331550786/10#10 date=1331986785
    Quote Originally Posted by 37313C253D3129500 link=1331550786/2#2 date=1331640580
    Something strange there, I guess its because the probe is measuring environmental temp rather than bean temp. as second crack occurs at around 220[ch8451] give or take - so hitting such a high temp at first crack is odd.
    I think I found out the reason for this - the fabric sheath at the connector end (to the DMM) has a little tear. When I press on it with my fingers, the temperature jumped up by about 30 degrees. I will probably need to take it to Jaycar to have it looked at. Unless you think its not the real reason for it?

  13. #13
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    Re: Behmor Roasted PNG Waghi AA CS8

    Behmor Coffee Roaster
    Re-reading this it occurs to me the wires at the multimeter end of the thermocouple might be shorting out? Maybe twisted together? This could explain it as well.

    Quote Originally Posted by 3E3A212B530 link=1331550786/10#10 date=1331986785
    Quote Originally Posted by 37313C253D3129500 link=1331550786/2#2 date=1331640580
    Something strange there, I guess its because the probe is measuring environmental temp rather than bean temp. as second crack occurs at around 220[ch8451] give or take - so hitting such a high temp at first crack is odd.
    I think I found out the reason for this - the fabric sheath at the connector end (to the DMM) has a little tear. When I press on it with my fingers, the temperature jumped up by about 30 degrees. I will probably need to take it to Jaycar to have it looked at. Unless you think its not the real reason for it?



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