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Roasting with a K-Mart convection oven

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  • #16
    Ok well here are the details of my attempts to night.

    1st batch
    1/2 cup Oven set at 200C on dial.

    5 mins - oven temp was 134C
    9 mins - oven temp 140C
    14 mins - still no first crack, turned oven dial to 225.
    16 mins - temp = 148C
    17 mins - temp = 152C
    17:30 mins - turned over up to full 250C
    18:20 mins - 1st crack, 1 bean
    18:42 mins - rolling crack temp = 167C
    19:30 mins - temp = 173C dial turned back to 225C
    20:30 mins - heard more cracks dial turned down to 200C. temp = 162C
    21:30 mins - more cracks not sure if still 1st or second crack but beans were black so pulled them out.

    Here is a photo
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    2nd batch

    75 grams (just under 1/2 a cup). Oven set at 225C.

    2 min - temp=133C
    6 min - temp=160C
    10 min - temp=160C, 1st crack, 1 bean.
    11:30 min - rolling crack, dropped oven dial to 200C
    Pulled around 14 mins, didnt hear second crack

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    3rd batch

    70 grams Oven set at 200C
    2 mins - temp=99C
    5 mins - temp=132C, set dial to 225C
    8 mins - temp=156C
    9 mins - temp=160C
    9:48 mins - 1 crack
    12:20 mins - 2 more cracks
    14:30 mins- few more cracks, could be considered rolling crack
    15:40 mins - drop oven setting dial to 200C
    17:30 mins - temp=143C
    19 mins - Pulled beans didn't hear a second crack at all.

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    So from what I can tell out of this is that I need to have my oven inside temp at around 160C before I am going to get 1st crack. Also that the 3rd attempt was probably the best one but I should maybe crack it to 250C after 5 mins and then drop it back to 225C after 1st crack. What are your thoughts??

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    • #17
      I think you are on the right path. Roasts 2 and 3 both look pretty good.
      Roast 3 is more like the profile I would aim for.

      The best feedback will be your taste buds.
      Let them rest for a few days (if you can) and do a side by side.
      If not possible due to the volume, then just jot down some tasting notes as you try each one.
      Make the notes relevant to YOU. EG: Don't try to describes notes of Juniper and Orange Blossom unless you have a palate that can actually make that sort of distinction.

      Enjoy the journey!

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      • #18
        Originally posted by fatboy_1999 View Post
        I think you are on the right path. Roasts 2 and 3 both look pretty good.
        Roast 3 is more like the profile I would aim for.

        The best feedback will be your taste buds.
        Let them rest for a few days (if you can) and do a side by side.
        If not possible due to the volume, then just jot down some tasting notes as you try each one.
        Make the notes relevant to YOU. EG: Don't try to describes notes of Juniper and Orange Blossom unless you have a palate that can actually make that sort of distinction.

        Enjoy the journey!
        LOL..Thanks mate, will give it a go and see how it tastes. Ill save the wanky tasting notes for wine lovers as I certainly dont have a sophisticated palate like that.

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        • #19
          I get very good results from a Hot Air Pop Corn pump. I have 2 types; The circular air motion and the vertical air. They both do a good job. I insert a metal (cloths dryer) pipe altered to fit both for the expansion. You can pick these up at Thrift Stores for approx. $5 -$6
          roger

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          • #20
            I have been roasting with a KMart rotisserie for some time but with considerably more beans. My load has generally been 400gm and to start with I was getting first crack at about 12 to 14 min and finishing at about 18 to 20 min. With the thermostat set on full (250deg) I was getting an oven temperature of about 220deg pre heating for about 15 min. I was dropping the temp to about 180deg a minute or so into first crack and then pulling the roast when the colour was about right. Lately however I am unable to get the same temperatures with the oven and wonder if the thermostat is dying, and the times have increased to the stage I am getting first crack at more than 20 min, so think I am baking rather than roasting, and the coffee is disappointing.
            I am thinking of modifying the oven by removing the thermostat and getting a power controller to give more direct control over the elements rather than the switching of the thermostat. This should then operate more like the proper drum roasters.

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            • #21
              I am thinking of modifying the oven by removing the thermostat and getting a power controller to give more direct control over the elements rather than the switching of the thermostat. This should then operate more like the proper drum roasters.
              G'day Ross...

              While an Electronic/PID Controller would afford you much better control over the temperature, have you checked that the heating elements haven't become encrusted with baked on coffee residues? Not uncommon unfortunately.

              Mal.

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              • #22
                Originally posted by RossWB View Post
                I am thinking of modifying the oven by removing the thermostat and getting a power controller to give more direct control over the elements rather than the switching of the thermostat. This should then operate more like the proper drum roasters.
                G'day RossWB,

                I 've been roasting for a few years now with a Behmor, and longer than that with a couple of heavily modified poppers, which I still use for most of my roasts. I prefer the better control and faster response that I get from the poppers.

                To control the voltage to the 1200W heaters of the poppers, I use 3800W SCR 's . Some overkill there maybe, but that's the way I like it.
                They are very effective and reliable, and I have only had to replace one of them after six or seven years of regular use, (maybe because of the extra wattage rating). I bought them on FleaBay for less than $10 each.

                If you want to mod your oven, there are 5000W , and even 10,000W versions for under $20
                They should be sufficient to handle the 2Kw of your oven, even if the ratings are a bit "optimistic" which is sometimes the case with stuff on the bay.

                Cheers, deegee.

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                • #23
                  The bottom elements are pretty clean. They get a bit of chaff falling on to them which gets burnt off. I’m away at the moment but will be home early April, so I’ll give them a clean and see if that makes a difference.

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                  • #24
                    I was looking at a 4Kw unit from a home brewing supplier for about $50. Will take a look on eBay as well.

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