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Corretto build

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  • Corretto build

    Hi all.... I recently found out about the corretto coffee roaster through a friend, and as a result, I've spent the last two weeks trawling the roasting section of the CS forums (didn't think to look in the equipment section), gaining as much information about corretto builds as possible. I've learnt a lot from the people here and even blatantly copied some nifty features from some of you

    After spending every minute after work of the last week, I got to finish it off today and fired it up tonight. Having read a fair bit over the week about correttos and briefly taking in information about roasting techniques (specifically Matt/designingbycoffee seeing I purchased the digital Bosch HG), it came time to roasting and I realised I had no idea, only knowing what the roast profiles generally look like.

    I started off with a Palsonic bread maker that I picked up from Cash Converters for $25.
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    Ripped everything out, leaving the motor, and wired in a switch for the motor and a small fan which hadn't arrived yet.
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    I wanted at least a little insulation and felt a steel sheet lid wouldn't be the best for keeping heat in. I found some old sheets of fibro which I cut up and sandwiched together between two thin sheets of steel. Makes for a good, heavy lid. I also wanted some control over the chaff so I welded up a few bits of pipe from work as an exhaust. will go through 3/4's of a can of MAPP gas while welding objects with such large thermal mass. You can't see it in the photo, but the top sheet of steel did buckle from the heat and not being able to expand due to the bolts. Nothing major though. I don't blame it seeing it took me so long to heat it up with MAPP gas instead of an oxy/acc torch.
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    Finished product. That wooden knob and mini fan....yep, ideas stolen straight from user fg1972
    I've still got to weld another extension pipe to raise the heat gun to avoid scorching the beans with the element so close. I picked the wrong pipe from work and the diameter was too large for the heat gun to have a snug fit. Will raise it 100-150mm this week. I have also wrapped the pan in two 1x1 fire blankets.
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    First roast...trying to figure out how on earth to tackle it.
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    All up, I have to say that, even after my first roast which I'm sure isn't great, it's a huge step up on the supermarket beans my parents buy (it's their house, I can't complain...but I kind of do a little lol) and almost half the cost!

  • #2
    I was also going to try to dismantle the heat gun and fix only the element and fan stack to the lid with the controls mounted to a box on the side of the bread maker, which would have involved making an extension on the wires to the element and fan. It would have made for a much nicer looking setup, even if I did have an awkward cable connecting the lid to the bread maker.

    I was able to take the guts out but the way the fan speed selector board, which sits in the handle, connects to the main circuit board makes it difficult to separate cleanly. I have no problem with soldering and circuitry, I just found it wasn't worth unsweating the two boards and then also somehow mounting the switches and controls to a box. Possible? Yes. Worth the investment of time and likelyhood of cocking it up? Not really. At least now I have a working heatgun complete with a warranty I can still claim (if they don't figure out what it's used for).

    Anyway....I still took photos for anyone who is interested...
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    It's not really visible in the photo, but the grey board, which is in the place of the handle, houses four lines which all make a solid connection through the circuit board above it.
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    • #3
      Nice work, well done!

      Don't worry too much about details to start with, just roast , take lots of notes and enjoy!

      You might not need to raise the gun much. With a fully insulated pan you don't have to use such a high heat.

      Although the exhaust pipe seems a bit small for the heat gun flow? You don't want to "choke" your hear gun, might effect its longevity being chocked? Just talking out loud here.

      Are the edges of your fibre sheet "sealed" in some way? You don't want fibres escaping into your beans.

      I want to do a similar lid setup on mine, and will try to fit a large mesh collector at the end of the exhaust to collect all the chaff, which should make it pretty mess free.



      • #4
        I'll see how I go with the taste of the roasts in the coming weeks and decide on the gun height from there. I might even insulate the pipe with some fire blanket, just because I can.

        I was wondering about the restriction of the exhaust vs the flow of the gun. The pipe is around the same size as the outlet of the gun, and the outlet has a disc in the middle to direct the air through the veins of the nozzle. I also had a theory that a smaller, rather than larger, diameter pipe would have a higher velocity of air which would carry the chaff more effectively. Although I did notice a lot of smoke coming out of the vents of the bread maker, more so than the pipe, which would be getting through the hole used to carry the heating element from the electrical bay to the pan surround. I wouldn't have thought the two bends cause too much of a pressure drop at the sort of rates we're dealing with, but maybe it is having a slight effect. It's done, anyway. Maybe it's something to consider on version 2.0.

        The fibro isn't sealed. It's cement sheeting rather than a fiber sheet, if that makes it any better for consumption? Haha. But no, I didn't think of that. Will check it out and see if it's drops any fine amount of cement dust. It seemed to be ok. I guess no one can tell me to add a teaspoon of cement to my morning coffee, now.

        My initial thought on the strainer to catch the chaff was a smallish type that we use at work in chilled water systems. It'd be about the size of the pipe I'm using for the exhaust. Although on second thoughts, it'd restrict the air flow a bit as the chaff built up. It'd need to be a fairly large strainer. Might have to think that one through a little, and get creative. It's not too messy as it is now, it seemed to dump the chaff all in one place for an easy clean up.


        • #5
          Great work Dan...

          Much better effort than mine. Lots of happy roasting ahead mate...



          • #6
            Nice job Dan. Keep us updated with your progress.


            • #7
              I modified my standard bucket bean cooler last night. Seeing I have already posted it in my roasting thread, I'm going to blatantly copy and paste the post here....This is a build thread afterall

              I super charged my bucket bean cooler. I spotted a few small evaporator fans laying around that I'd scrapped from a fridge at work. They were fitted to brackets which would allow it to sit perfectly on top of the bucket lid. Whipped up an extension of the bracket, soldered the wires to a power cable, and it provided decent air flow onto the beans. It worked and it was good, on the first roast, but I thought I could do better.

              I've been annoyed by the little bits of chaff that remain in the beans. I'm not sure that there would be enough to be too noticeable in the cup (how much is an acceptable amount?), but I'd prefer there be none. I figured I could get some decent air flow moving up through the beans, along with the help of the exhaust fan currently in the bucket, causing the chaff to be blown away.

              Ended up flipping the exhaust fan the other way, so it blows upwards, and making more mounts for the evaporator fan to mount it within the bucket.

              Yep...No more chaff You only need to see the video to see how much power this thing has. All I need to do is stir the beans around a little and the chaff flies out....along with the odd, lighter bean here and there!

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