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I need some help with my gogomo...uhh...Corretto

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  • I need some help with my gogomo...uhh...Corretto

    Hi all,

    I had the day off did what all other uni students would do - rip open a breadmaker and rewire it for coffee roasting! Anyway, long story short, Im having problems with the roast (Id say its currently worse than my Crazy Popper roasts).

    In my grubby little hands Ive got:

    - Tiffany breadmaker, paddle (bare metal), wiring placed to bypass electronic controls
    - GMC heatgun (the 2 speed variable temperature one)
    - Pedestal fan heatgun mount
    - Bathroom extractor fan bean cooler

    Okay, fired the Corretto up and did a few roasts as follows:

    1. Brazil yellow bourbon - Overestimated how much heat the HG puts out, so 1st crack at ~17 minutes. However, about 1 minute later, I hear the distinctive sound of 2nd crack (assuming its the same as popper roasting) as well as the associated smoke. Hmm...beans are dumped and cooled, arent too bad colour wise, could be a little more even, no oil on surface. Mainly worried about the tiny interval between 1st and 2nd crack...

    2. Brazil yellow bourbon attempt #2 - This time, first crack at 8-9mins, DMM reading around 210. Again, 1 or 2 minutes later, hearing/seeing second crack. All hands on deck to reduce temperature (not a good thing I know) as its around 220º. Anyway...too late so beans are dumped at ~13 mins. Darker than the first roast, still no oil.

    3. Tanzanian ameru? AA (or something like that) - Enough wasting the Yellow bourbon, so using up some of the older greens. Was aiming for a 8-9min 1st crack, maintaining at 205-210 for 4-5 mins then hopefully 2nd crack. 1st crack at 205-210 at around 9 mins, pulled the HG out a little and dropped the temp as well trying to maintain temperature. However, once again, 2nd crack rears its ugly head (I guess its not usually ugly...) as the temp shoots to 220º once again. Took my time getting them out @ 12-13 mins...appears quite disgusting - black, oily, Starbucks-esque. Dumped it straight into the hopper since it probably wasnt worth waiting for it to rest.

    Anyway, it appears that my problem is temperature control...I guess Id like a little help with:
    a) A nice basic roast profile to try and follow - currently using 1st @ 8-9, 210º. 2nd @ 15-16, 230º

    b) Some suggestions on controlling roast temperature - should I just keep it simple and move the HG in and out?

    c) Do I have thermocouple problems? Im using the Jaycar datalogging DMM (but cant datalog right now, waiting for my eBay USB-RS232 converter to get here (yay for laptops with no serial seems like just yesterday that I was plugging modems and ball mice into them...). Ive drilled a hole through the BM exterior into the bread tray, tip of the thermocouple is in the bean mass close-ish to the gap in the L-shaped paddle. Could it just be that the thermocouple temperature reading is incorrect and making me roast at higher temperatures than indicated?

    d) Does anyone have a datalogging solution for Mac OSX? Ive got I guess I could run Windows datalogging software in a window, but Id rather not if possible

    Thanks in advance for anyone reading through this


  • #2
    Re: I need some help with my gogomo...uhh...Corret

    Hi Aaron,

    Heat guns put out lots more heat than a popper.....

    Firstly your time to 1st crack could be a little longer - heatgun further away from the beans at the start......

    But once you get to first crack reduce the heat by taking the gun away a fair bit at 1st crack...... you will need to experiment with your particular gun.... but you want it far enough away so the temperature still goes up - but very slowly. You dont want the temperature to stall - and certainly not go backwards......

    The popper can barely get hot enough to reach second crack.... especially if the day is cool. A heatgun on the other hand can heat whatever is in its path to 600C if close enough..... beans to charcoal in seconds from the end of 1st crack..... so back off the heat quickly.

    That is where variable output heatguns make like so much easier... you just turn the output down rather than having to move the gun away.....

    So forget just about everything you learnt with a popper...... a heatgun is a far more serious heat source - and must be treated with respect.

    The temperature probe reads the air temp between the beans... not the actual bean temperature.... I tend to use it not as an absolute temperature indicator.... but to show how things are changing....

    e.g. if 1st crack is 195C..... back the heat off so that it goes up by say a degree every 30 seconds..... and if 2nd crack occurs at 215.... which is 10 minutes later.... thats great.... so I use it more as an indicator of rate of change than absolute temperature.....

    And now with PID control it is exactly the same... except the PID sets the ramp rate for me..... and repeats it exactly the same each time.


    • #3
      Re: I need some help with my gogomo...uhh...Corret

      Ive been happy with FC @ 9 min and SC @ 15 as a general profile.


      • #4
        Re: I need some help with my gogomo...uhh...Corret

        Ive got the GMC HG, but a different BM (Breville Ultimate Bakers Oven).

        I tend to get 1st crack around the 11 to 12 min mark and 2nd around 16 to 18 mins. Times are for 400g of green beans.

        This is with the HG going full ball, sitting about 1.5cm above the edge of the BM bowl (it has to sit at that height because I dont have a stand for it yet and its resting against the lid and body of the BM). I usually drop the temp on the HG a bit around 1st crack. Cant tell ya exact temps cause I dont have  DMM.

        I know when Ive held the HG any closer that 1st & 2nd crack tend be very close together.

        Could depend on the bowl of your BM. Mines got one of the full loaf, wide bowls (1.2 kg loaf size). A smaller bowl would probably heat up quicker.

        My Pedestal fan is also blowing just over the top of the machine to get rid of the chaff - so that probably helps too.


        • #5
          Re: I need some help with my gogomo...uhh...Corret

          Hi Futorima

          Im pretty new at the corretto too, and have had some fantastic sucess and at other times have had similar results to you where the 1st and 2nd cracks kind of blurr together.
          In the cup, the results are still pretty good, and hey the hands on approach is the best way to learn about bean behaviour

          I have temp control on my heat gun, but I find it more effective to move it further away rather than adjust the temp.
          Mine is mounted on a microphone boom stand with a HD spring loaded mike clip so it is easy to do this. [dont tell the drummer!]

          Being in Melbourne, air temperature and wind seem to be factors, Im getting better results with the tip of the gun just inside the BM, and its temp setting a bit lower [say 500-550]
          But of course the shape & size of the BM basin also dictates the most suitable placement.

          I never wanted to "stall" the roast between the cracks, but whilst your learning I think it may be easier to risk doing this, just to get a feel for it.
          Remember, 1st crack gives of heat so you need to drop the heat pretty rapidly.


          • #6
            Re: I need some help with my gogomo...uhh...Corret

            I use the corretto occasionally (usually iRoast) so its a pretty
            rudimentary setup. TC probe comes in from underneath about .5cm
            in corner diagonally opposite where I point the HG, so that Im measuring
            bean mass not air from HG.

            Temp adjustment is by moving the HG (I hold it, no stand yet). I warm
            the beans pretty slowly at first, trying for a drying phase of about 3 mins
            at around 150/160C. Then move the HG in to heat more quickly to get
            to FC (about 205C on my t/c). I take care here, FC is exothermic so Im
            trying not to inject too much heat, attempting a slow temp rise. I can
            usually get a reasonable gap (3 mins or so) before SC starts.

            It takes practice. Ive found it easier to work with batch size around

            The DMM s/w works fine with Parallels. Anything else is too much
            of a pain -- I tried


            • #7
              Re: I need some help with my gogomo...uhh...Corret

              Wow, thanks for all the info girls/guys - Ill have to do another roast sometime next week I guess and try control the temperature between 1st and 2nd better. Will probably try dropping the heat from 650 to 500 and see how it goes. Reubsters tip about sticking the HG nozzle into the BM pan will probably come in handy; the first roast I did had some trouble coming up to temp when the heat gun was 3-4cm or so above the rim of the pan (as well as the temperature going backwards because of the wind).

              I was thinking of roasting again tonight (just because I want to play with it ) but the ridiculous wind around the city today put me off the idea let alone the 400g of beans sitting next to the machine...

              Come to think of it, does anyone use the tips which come with the HG when roasting, or without attachments? I guess it wouldnt make too much of a difference since the beans are getting agitated anyway, but has anyone else had a play with this?



              • #8
                Re: I need some help with my gogomo...uhh...Corret

                Not yet but I thought Id try one next batch.
                Just the simple short extension one.
                It slightly reduces the output hole as well, so may concentrate the heat a touch.


                • #9
                  Re: I need some help with my gogomo...uhh...Corret

                  Nah havent used them, yet.


                  • #10
                    Re: I need some help with my gogomo...uhh...Corret

                    Originally posted by futorima link=1188476120/0#6 date=1188559599
                    Come to think of it, does anyone use the tips which come with the HG when roasting, or without attachments? I guess it wouldnt make too much of a difference since the beans are getting agitated anyway, but has anyone else had a play with this?
                    Gday Aaron,

                    Yes, I did at first with my Breville Big Loaf BM, as the pan lays on its side rather than vertically, so thought Id use the Spreader attachment to try and distribute the hot air over more of the bean surface.

                    Sounded fine in theory but didnt work well in practice as the extra surface area of the attachment acted as an efficient heat radiator so that the air was being cooled before it hit the bean mass. Went back to using the plain HG nozzle and found that this worked a lot better and more predictably than with an attachment, so have never bothered trying again :-?.



                    • #11
                      Re: I need some help with my gogomo...uhh...Corret

                      Originally posted by futorima link=1188476120/0#0 date=1188476120
                      d) Does anyone have a datalogging solution for Mac OSX? Ive got I guess I could run Windows datalogging software in a window, but Id rather not if possible
                      Hi Aaron,

                      This might not be suitable for you depending on how much trouble you want to go to but I will post it anyway for your benefit and any advanced macosx users that might want to try this.

                      First off, I havent looked for a mac datalogging solution since June 2007 so there might be something new since then.

                      What I found at that time was some software for linux/unix called QtDMM. Website is here:

                      If you are good at compiling software for UNIX type systems and good at getting all the requirements sorted (Such as getting Qt working) you might be able to get this working on macosx. You would also need to get your serial port working with macosx also. If you are not good at compiling software for UNIX, there is probably not much point reading the rest of this post (accept for the bit at the end regarding parallels).

                      I use QtDMM on linux and access its display remotely on macosx using X11, so I didnt put a lot of effort getting it to compile on macosx. It did not compile first go as it did not have Qt available.

                      One thing I did get working on macosx is just the datalogging part without all the graphing etc. To do this, I got QtDMM2 which at the moment just does the datalogging. By that I mean it reads the values off the multimeter and you can record these to a file for later interpretation. It does not do graphing of its own. The datalogging part of QtDMM2 does compile on macosx as it does not require Qt (at least it did compile for me, I have the developer tools installed for macosx, not everyone does).

                      Some random tips for getting this working on macosx:

                      - Download and ungzip/untar QtDMM2 0.2
                      - when doing a "./configure" I got errors indicating that there was no Qt. This can be ignored as it is not required.
                      - compile using "make"
                      - once it is compiled, the binary is called cdmm and will be located in the "bin" directory within the "QtDMM2-0.2" directory. You could move cdmm to somewhere appropriate.
                      - find out the name of your RS232 device. My RS232 port is builtin and is accessible from both /dev/tty.serial1 and /dev/cu.serial1
                      - you can run the binary from the command line specifying the multimeter type and RS232 port location (dont forget to plug in your multimeter and turn on the RS232 output). For me, the following command outputs readings from the meter to standard out:
                        ./bin/cdmm --device="Digitech QM-1538" --port="/dev/tty.serial1"

                      device = Digitech QM-1538
                      port = /dev/tty.serial1
                      opening: /dev/tty.serial1:2400:8:n:1SRTR
                      V0: 018.6  DU
                      V0: 018.6  DU
                      V0: 018.6  DU
                      V0: 018.6  DU
                      V0: 018.6  DU
                      V0: 018.7  DU
                      V0: 018.7  DU
                      V0: 018.7  DU

                      Note that the above sample output is in degrees Celsius even though it does not state that.

                      - You can send that output to a text or .csv file to save it so you could open it up in a something like a spreadsheet or graphing program:

                      ./bin/cdmm --device="Digitech QM-1538" --port="/dev/tty.serial1" > /Users/yourusername/Documents/multimeteroutput.csv

                      If you want to see other options to cdmm do the following:
                      ./bin/cdmm --help

                      If you have a different multimeter, run this to see a list of supported multimeters so that you have the right name to use in the --device= option:
                      ./bin/cdmm --list-devices

                      All of the above sounds like a lot of effort to me, though it might be suitable for some people. If you have linux available, I would recommend using QtDMM with that (it is available as an installable package for some linux distributions), or you might just have to use the windows software that was downloadable from jaycar last time I looked.

                      By the way, if you end up having to use parallels, you might find that it cant access the USB-RS232 port converter if macosx already has a driver loaded for it. I think there is an option in one of the parallels menus to access a plugged in usb device directly if no macosx driver is loaded. You might need to do that.

                      More details on using QtDMM with a QM-1538 available from here onwards

                      Good luck,


                      • #12
                        Re: I need some help with my gogomo...uhh...Corret

                        Hi all
                        Excellent post fabcat. Im a Linux user and didnt know of that site. It will be vey useful, particularly as it supports quite a few DMMs.


                        • #13
                          Re: I need some help with my gogomo...uhh...Corret

                          Hi all;

                          Im almost through that first batch of beans, surprisingly the Brazils didnt turn out too bad (with milk), pulled some OK naked PF shots with them too. Round 2 with the BM/HG will probably happen tomorrow, Im thinking of doing a popper roast just to compare the results as well. Ill run the HG without any attachment and see how that goes too.

                          Wow fabcat, looks pretty much like a how-to

                          Ive been trying to play about with that program, but initally got stumped at the qt error when entering ./configure in terminal. Im still waiting for my USB/RS232 converter to come from Hong Kong or somewhere, so Ill have more of a play when that gets here.
                          Pity I dont know more about terminal; Ive only been using a Mac for a few months and was purely a Windows/DOS user prior to that (I grew up writing batch files for my sisters to play games on the computer; Win3.11 seemed only like...umm...not quite yesterday, and I still remember that tanks/cannon game that came with my QBasic floppy...)

                          ...Anyway, I know diddly-squat about Terminal, so Ill have a play about with that later.

                          Time to sleep, patient to see @ 8.30am; I really hope the vacuum breaker valve doesnt stick so I can have an early coffee...touch wood...:S



                          • #14
                            Re: I need some help with my gogomo...uhh...Corret

                            Okay, looks like the problem is solved;

                            Ripped through about 1kg of beans (I love larger batch sizes now), now with a lot more control over temperature, rate of temperature change and roast time.

                            Things I did differently:
                            - Heatgun at around 500-550ºC (my 500º light was fully lit, the 650º light was flickering
                            - No nozzle on the HG, placed tip of nozzle at the lip of the BM bowl
                            - Paid CLOSE attention at the first sign on 1st crack and adjusted temperature accordingly

                            1st crack seemed to come around at 8-10 mins, 2nd crack at 15-18 mins. I even tried a 400g batch and it came out great (look/smell anyway, Ill see how it is in a few days)I can graph out my temperature log for anyone to analyse if anyone wants it.

                            Maybe I can even start using the popper for popcorn again...