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Thread: readeral's KKTO

  1. #1
    Senior Member readeral's Avatar
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    readeral's KKTO

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    N.B. This is a design entirely developed by Koffee_Kosmo, merely partially implemented by me.

    With much thanks for help from KK and prompting from nikko, here's a new thread for my new KKTO build I've been putting together.

    As my frankenpopper has been a fun experiment, but no where near consistent enough for my needs - the KKTO was a necessity for keeping up the newly formed home coffee habit!

    I managed to score the correct pot set (Metal handled Arcosteel) on scumtree for $30 and so it all started.

    KK sent me a purpose-manufactured motor, drive shaft and washers, agitator materials, insulation and false floor.

    I purchased from fleabay some hi-temp hosing, a DMD and thermocouple.

    Still to get is the TO itself (hopefully it'll come back into ALDI, otherwise I'll get a Kmart one, they're the same), a power 12v 2.5A power supply for the motor, a silicone gasket maker, and materials for the pot platform.

    What follows are some pictures of the build so far.

    This is the pot set recommended for a 'standard build':
    1_pot_set.JPG

    This is the fitted silicone. Note that the top tube (green) has been split carefully down the middle to sit over the lip. The bottom tubing has been attached with a 2mm tube connector from Bunnings (I had to trim the connector down to make it sit flush against the pot as it's square). It sits above the small lip, and will fill the gap made between the two pots when they're put together.
    2_fitted_silicone.JPG

    This is a photo of the black tube filling the gap between the pots. I will later use some silicone gasket maker to hold it firmly in position.
    3_sitting_silicone.JPG

    I had to drill my own pots, so I used the following method to find the centre, as I wasn't willing to trust the rings on the pot itself. Note the lines drawn to intersect the pot edge at two points. I then found the centre of this line and drew a perpendicular line across and through the centre of the pot. I did this 3 times and approximated the meeting point. It was very slightly different to the lines already on the pot.
    4_pot_centre.JPG

    This is the resulting drilled hole. 18mm in diameter, which is good as the hole ended up having drifted 1mm off centre once we'd finished.
    5_drilled_hole.JPG

    The insert was also drilled at 14mm, but we just had to go with the already present drainage holes as our drilling guide.

    More to come...
    Last edited by readeral; 13th September 2015 at 01:15 PM.

  2. #2
    Senior Member readeral's Avatar
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    This is the drilled insert with the drive shaft fitted, one washer between the drive shaft collar and the insert
    6_shaft_underside.JPG

    This is the shaft from the inside, another washer between the holding plate and the insert
    8_shaft_inside.JPG

    This is the wire that will be agitating the beans - it's been marked to correct length so that the wire can be bent at 90 degrees to insert into the drive shaft.
    7_marked_wire.JPG

    Here's the bent wire:
    9_bent_wire.JPG

    Here's one of the wires inserted before the holding plate is put on:
    10_inserted_wire.JPG

  3. #3
    Senior Member readeral's Avatar
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    Here's the agitator wire inserted with the holding plate attached (backwards - so it would still hold the wire but not get in the way of bending the wire. This cup was my guide for getting the curve correct
    11_agitator_straight.JPG

    The finished bent wire agitator. Not perfect, but good enough.
    12_agitator_bent.JPG

    The finished bent wire agitator from another angle. I will probably trim off the excess wire at the top, and will probably bend the bottom wire back on itself and attach a metal spring for a bit more heft to move the beans around at the bottom.
    13_agitator_bent.JPG

    So what's next?
    At the moment I have to make some adjustments to the aluminium false floor that I have, and then I will be using the gasket maker to seal it in place at the correct depth, with gaskets made for the drive shaft on the external pot (reduce that 18mm hole) and the aluminium false floor (in my instance, 16mm hole)

    After that, I'll need to build a platform for the pots to sit on (and some centring posts) as my drive shaft protrudes by 46mm. I'm planning to sandwich 3 sheets of MDF together, and the motor provided by KK will be attached to the bottom of this MDF.

    I'll then likely put some castor wheels or legs on the bottom.

    Updates as it moves forward!

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    It comes together quite nice.
    Thanks for the photos.
    Adi

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    Senior Member readeral's Avatar
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    Thanks to adifoto for doing the drill holes in my pots!
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    Senior Member nikko.the.scorpio's Avatar
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    Nice work Al! Bloody heck I look at how quick and nicely thats come together for you and I think there's REALLY something to be said for buying the pre-made perfect bits from KK instead of putting together from this and that as I've done.

    Looks great and look forward to seeing how you finish it off.

  7. #7
    Senior Member readeral's Avatar
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    As I said to Paul yesterday, I measure thrice cut once :P But as you say, all credit to him for the excellent drive shaft and agitator.

    My biggest problem is how to mount the motor. It just seems crazy to join 3 pieces of MDF together, but I can't think of anything else that would be as stable!

    Picked up a round file today and some RTV gasket maker - so all the internals will be done this evening. Leaves mounting, electrics and the TO to go.
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  8. #8
    Senior Member readeral's Avatar
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    Think I've found a possible low effort solution, but not the cheapest if talking raw materials... but my time is worth something too, and right now with an erratic popper, I'm back to buying beans from my local roaster.

    This chopping board from Wiltshire ('Wiltshire Gourmet chopping board') is 45mm thick - only 1mm from my needed thickness. I'll just drill it, and then test it for suitability. If need be, I can cut a 1mm thick plate of aluminium to go between the motor and the chopping board to make up the extra distance, but my hunch is I might have enough room in my measurements. We'll see!

    89022652.jpeg
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    Necessity being the Momma of Invention again!!!

    Grand thread about your journey,readeral.

    Thanks for posting everything.

  10. #10
    Senior Member Koffee_Kosmo's Avatar
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    Glad to see that it's all coming together nicely for you, and my instructions were easy to follow @readeral

    KK

  11. #11
    Senior Member readeral's Avatar
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    Quote Originally Posted by Koffee_Kosmo View Post
    Glad to see that it's all coming together nicely for you, and my instructions were easy to follow @readeral

    KK
    The breadth of your documentation is sensational!

  12. #12
    Senior Member readeral's Avatar
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    I adjusted the aluminium floor to be a little more centred with the round file - I had issues with the drive shaft rubbing, but they've now been eliminated and everything sits nicely.

    Next I used a pacer pencil to draw little markers through the internal pot to the outer pot, so I could know exactly how deep the insert pot sat.
    1_markings.JPG
    These lowest holes were 15mm up the side of the insert, so I measured 15mm below this line for the bottom of the insert. My drive shaft collar sits 10mm further under that, and I wanted to have 5mm gap between shaft collar and the false floor - so I found the point 30mm below my markings by inserting my false floor, and using a set square I levelled it out at 30mm below my marks.
    2_square.JPG
    Then I took a sharpie and drew this line around the insert and pulled it all back out again.
    4_line_1.JPG5_line_2.JPG
    Then I went to work with the Permatex, placing a ring of silicone around my drive shaft exit hole from the inside of the outer pot.
    6_gasket.JPG
    Last edited by readeral; 16th September 2015 at 10:17 AM.

  13. #13
    Senior Member readeral's Avatar
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    Next went down a layer of insulation, and Permatex was placed on this layer, along with another ring around the exit hole. I kept doing this until all the insulation was in place.
    Attachment 10432Attachment 10433

    After that, I wrapped some aluminium foil around a pen and pushed through the hole, just to make sure that all the strands of insulation were neat against the side and that the hole was clear for the drive shaft. This didn't work as well as I had intended, but was ok.

    Finally the aluminium false floor was placed back in, and levelled up to my pre-drawn line and checked with a spirit level, and then I ran a ring of Permatex around the outside (This was freakin' hard by the way, this stuff is stiff and also in a metal tube, you need strong hands if you want to make it all the way round (I didn't)). I then used the edge of a display folder cover that I'd cut up to smooth it out (the folder had a nice curve on the edge) and I was done.

    Attachment 10434Attachment 10435
    Tomorrow once all is set, I'll probably turn it over and add another ring of Permatex at the bottom to try and centre the drive shaft, as the hole is 5mm larger than the shaft is.

    Thinking it through, if I had to do it again, I probably would put a ring of Permatex just below my drawn line before putting the insert back in, as that would mean it was supported from the underside, not just being upheld by the stuff I added from the top. However, I did have a small gap down between the wall where it may have seeped through - so here's hoping it holds ok.

    Anyway - that's it for today!

    Online, I purchased my chopping board to mount the motor on the underside, and for the pots to sit on. KK has warned against using this type as it's construction in blocks may mean it could be at risk of warping. Don't take this as my recommendation, but I'll take the risk I think, as it's already ordered. Instead of using aluminium to make up the 1mm distance (if even necessary) I think I'll use a thin amount of rubber, with the idea of isolating the motor to reduce vibration noise, but also protect it from any potential damage if the board does eventually warp out of shape.

  14. #14
    Senior Member readeral's Avatar
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    I also placed a ring of permatex on the aluminium false floor just inside the drive shaft hole - but unfortunately it didn't take (I put in the shaft, and it gripped to the shaft and came away from the aluminium.)

    That was a bummer - doesn't bode well for the rest of the permatex (without the support from underneath - see previous post) but maybe it will be ok. What I'll do is rough up the aluminium with some coarse sandpaper and put some more down.

  15. #15
    Senior Member readeral's Avatar
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    Ok, time for an update - been two weeks and I've just managed to pull almost everything together.

    Firstly - I didn't go ahead with the chopping board posted above. Two weeks after ordering it, I contacted the business I bought it from.. turned out it wasn't in stock. Not to worry, I went with another Wiltshire board, this time the 'Chop Chop' medium size, also 45mm in thickness. Ordered it from Harvey Norman online and arrived a few days ago.

    I must say - drilling the holes was a gigantic pain in the ass. Again I had help from adifoto to drill these holes. The thicker the material, the greater the possibility of not drilling straight down. Unfortunately the press drill was not big enough to reach the centre of my chopping board, and so we needed to use a wireless drill. I recommend getting access to a press drill the right size if anyone is following this up.

    The other recommendation I had from KK was instead of going with a 45mm thick board, to have a thinner platform and raise the pots up from the platform. This would have saved us the headache of less than straight holes - and I could have used some 20mm ply. Anyway - in my optimism for managing the thicker board, we went ahead. I just recommend considering this more carefully than me! Can be done, you just need some way of guiding your drill straight down.

    I don't have any photos of the drilling, but we drilled the shaft hole first, and after doing that, lined up the motor and drew with a pacer, the positions for the screw holes. I tapped a screw into the wood for a drill guide to start each hole and we got to it. This was our second mistake..

    What we should have done, was mark out and drill the first hole, screw down the motor with this one hole, ensure the shaft hole and the motor socket lined up perfectly, and then marked and tapped a drill guide for the second hole, repeating the process for each hole. Instead, we drilled 3 holes (having tapped a start for all 4) and realised the final one was going to be out of alignment. We needed to re-drill all our holes a little bigger to compensate.

    This wasn't the end of the world, as with the addition of countersinking our holes and KKs supplied washers, we could screw it down tight enough to secure the motor in proper alignment with the shaft hole and not move. Well... might need re-tightening in the future cause it's not guaranteed not to slip.

    KK did supply some bolts that were suitable for his manufactured base, but as I didn't have one of those, I went and bought some 50mm bolts with the correct thread.

    Here's the end result (yes I chose to put 'chop chop' top side up, because the board has built in handles that don't function upside down):
    IMG_1903.jpg

    So with all that securely in place, we then drilled some holes in a random bracket I had sitting around. Some sort of alloy, bent a bit under the pressure of the drill but didn't matter - we took to it with a hammer. Having drilled a hole, I then secured a 2.1mm DC socket to it, and we screwed it to the bottom of the board. I had grand plans for drilling holes through the board and securing the plate up the other way (as per an approach by KK on another forum) but by this point we'd been wielding the drill for 3 hours and couldn't be bothered anymore. Here's the result:
    IMG_1905.jpg

    Finally, I spend $9 on some clearance (ugly) furniture legs from Bunnings, got some wood glue and glued them to the bottom of the chopping board, let it set under pressure for 12 hours, and the foundations were complete!
    IMG_1911.jpg

    My wife soldered my motor to the socket (I'm _not_ an electronics guy) - we plugged in the 12v 2.5A power pack and gave it a go to test the alignment of the shaft hole. This youtube is the resulting effort.


    This second one is shorter but easier to see what's going on.


    I do have a bit more to go:
    - I've clamped my cable to the board using those little cable clips you can get from bunnings - but I want to cover the motor and the socket wiring with some sort of plastic casing (probably from Jaycar) so they can't get knocked around.
    - I've got a fire blanket I need to sew and cut holes in for the pot handles and use my cable ties to secure. Eventually I'd like to secure it with velcro (like a rectangle with velcro at each end, holding the fire blanket tautly to itself) but cable ties will do for now.
    - I need to put auto-centring guide to ensure my pot set does not shift and put pressure on the motor. In this regard, having a 45mm board is helpful as the risk of lateral pressure on the motor is lower. I'm considering either nailing down some leftover silicone tube I have from the build, or using wooden blocks.
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  16. #16
    Senior Member readeral's Avatar
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    Here's the photos that were meant to be visible in post #13
    3_balancing.JPG7_insulation.JPG8_insulation_2.JPG9_hole_prop.JPG

  17. #17
    Senior Member readeral's Avatar
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    A sneak peak of a tantalisingly close to finished KKTO ImageUploadedByTapatalk1444046666.739396.jpg
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  18. #18
    Senior Member Koffee_Kosmo's Avatar
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    Quote Originally Posted by readeral View Post
    A sneak peak of a tantalisingly close to finished KKTO ImageUploadedByTapatalk1444046666.739396.jpg

    You followed the instructions and recommendations to the letter and you have been rewarded with a well made roaster

    Give yourself a few settling in and training roasts and you should be roasting like a pro fairly quickly
    Again follow the instructions and tips I have provided and stick to the sweet spot green bean weight I have noted

    KK
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  19. #19
    Senior Member readeral's Avatar
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    Another update before I post some things later tonight about what I did with the fire blanket..

    So I hit a snag earlier today. The motor would run, and then slow after about 25 second, and eventually (almost) stopped at 30 seconds. I could pull the pots (with some force, as the shaft was sticking in the motor!) and put them back in again, and it would run fine for a further 30 or so seconds and stop. I wasn't sure what it was - so contacted KK, who gave me some suggestions.

    The issue was that the drive shaft hole Adifoto and I had made, although happily spinning freely in the workshop with our fingers twirling it, was not wide enough for motor driven use. This was indicated by the little aluminium shards that had begun to accumulate on the underside of the motor and in the walls of my wooden base. I suspect it may have been caking the walls and jamming the shaft, and also falling into the socket where the shaft and motor met, and holding the shaft tightly.

    So I pulled it all apart, went at the wooden base with a round file, widening the hole and smoothing it out - put it all back together again, and it's running happily with no problems (cross fingers!) - KK has also asked me to carefully inspect the motor internally for bits - anyone owning a KK motor should contact him about this step.

    So - I've learned that there does need to be enough room for the shaft to move and never rub - again another consideration for anyone considering a thicker base.

    KKs support and instruction throughout this build has been fantastic - suggestions at every step, feedback on my kooky ideas and recommendations to realign my thoughts.

    So later will be update about blanket, and details on first roast.

    Al
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  20. #20
    Senior Member readeral's Avatar
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    Ok. Here's the fire blanket update. Images are above so I won't repost them.

    I got the fireblanket from Adifoto - he'd used a small part of it in the bottom of his Corretto, so I used the rest. He hadn't used much, but the rest of it was perfect size for me to fold for the height of the roasting outer pot.

    I cut off the black tabs, and folded it lengthways, taking the outer quarter in to the middle (like folding bedsheets) and then folded it in half again so it was 1/4 of it's initial width. My wife sewed from the folded edge down to the open bottom 5 times at various points to keep it together.

    Next I took a length of baking paper and made a template of the outer pot of my roaster. I cut it to the correct width (the height of the outer pot) and cut one handle hole for one side, attached it and wrapped it around so I could mark the next spot for the next handle, then took it back off and cut that handle hole as well.

    After I had created my template, I put it on the stitched blanket, and drew the handle holes onto the blanket. Then I took a permanent marker and marked ~3mm around this rectangle hole. My wife then used a very tight zig-zag stitch to stitch around each marked rectangle. We wanted to to buttonhole stitch, but it wouldn't do it that big. Oh well. Also, the blanket didn't feed through because it's slippery, so needs to be carefully pulled along.

    Finally I took to it with a Stanley knife, cut a slip right through the centre of each rectangle (left to right) and ensured that it started and finished 1 cm from each side. From that edge, I then cut right into the corner to make little triangles. So the handle holes were made.

    I attached the blanket as you can see in the picture above, with the bottom folded over where there was an additional ~2cm of blanket. We then wrapped the rest of the blanket around, measured how much extra to cut off (with an inch of overlap) did another tight zig-zag stitch and cut it off.

    I haven't done this, but will be attaching some velcro, so it can be removed and replaced as necessary (for checking pot centring etc.) - right now it's being held with zip ties. This might be a more permanent option, but I suspect they will loosen over time, because the fire blanket does get warm.

    Why did we have the open side of the blanket at the bottom, and fold it over? Because if I want to I could slip in to each slot made by the downward stitches some more insulating material to make the fire blanket more effective during winter. I haven't worked out what that material might be (don't want it to be a heat sink instead!) but I'll keep you posted if I end up doing it.

    Any questions just ask me, here's two more pictures so you can see the stitching.

    IMG_1927.jpgIMG_1928.jpg
    Last edited by readeral; 7th October 2015 at 05:49 PM. Reason: Not sure why the pictures are sideways - they're right way up on my computer

  21. #21
    Senior Member readeral's Avatar
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    First roast! Would love some feedback and suggestions on how to better my roasts. That being said - it was really quite easy!!!

    I followed KKs instructions to "let the roaster do the work"... almost. Couldn't help myself.

    I started with 555g of some Brazil coffee (It's all I had left) and let the roaster preheat to 250 degrees. I opened it up and dumped the beans, and let her go!

    There were two points that I mucked around with the thermostat (told you I couldn't help myself), and to be honest, I should have just let it go. You can see it in the graph. The second time was right near the end of the roast, I turned it down, and then back up - might have been cause of my issues I'll talk about in a sec.

    The motor ran flawlessly - it did increase in it's noise a little bit after about 12 minutes, but nothing worrying.

    The one thing that worries me is that I couldn't hear 1st crack at all. Might be because of the beans, I know to expect various different volumes from different beans. Just sucked not to have that on the first roast. I'd intended to push to 7 degrees beyond first crack, but because I didn't know where it happened, I couldn't do that.

    So - the roast took 17 mins 30 sec, the total mass at the end of the roast was 475g, so a total mass loss of 15% (give or take for my dodgy scales) - the roast ended up darker than I would have liked (I don't have a CS scale to tell you what it was) but it was definitely a dark roast. No tipping, but maybe a little bit of scorching? Hard to tell. It's fairly even, just darker than I like my beans (and darker than I have seen from local roasters).

    Here's a picture of my roast log (using RoastLogger - I have a Mac, which isn't rating high on Andy's carefactor for CS Roast Monitor - but this software works just fine) - you can see the bit at the end where my RoR for the final 2 minutes. I couldn't tell because I forgot to put smoothing on, and so it was a bit all over the place... but post roast I smoothed it out and can clearly see the trend in the wrong direction!
    Brazil 7-10-15.png
    And here's a picture of my beans in my cooler (in natural light at 5pm) you can see there are darker beans consistently through there - a bit too far for my liking.
    IMG_1944.jpg

    And here's bonus pics of how I attached my temp probe. It's a 5mm probe, not the CS one, but I'll definitely be buying the 3mm from Andy soon, cause as you can tell from my graph above (and the bottom of my dip on the roast profile) that it's really not a very quick probe...
    I grabbed two M3 12mm bolts and nuts, with two spare M5 nuts I had lying around, and two M5 washers, and thread it through the roast chamber wall. Being M3 bolts, no extra drilling required, and with the M5 nuts keeping the thermocouple from slipping, and the washers keeping it in place, it barely moved throughout the whole roast! I could tighten it enough that the thermocouple was not touching right at the bottom of the roast chamber.
    IMG_1936.jpg
    IMG_1937.jpg
    Last edited by readeral; 7th October 2015 at 06:33 PM. Reason: Fixing images

  22. #22
    Senior Member chokkidog's Avatar
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    Hey readeral....those links in post#21 are invalid......
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  23. #23
    Senior Member readeral's Avatar
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    Ah dang it, that's twice I've not been able to post them. They work for me! Not that helpful for other people....

  24. #24
    Senior Member readeral's Avatar
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    Images for post #21 (in reverse order)
    IMG_1936.JPGIMG_1937.JPGIMG_1944.JPGBrazil 7-10-15.png

  25. #25
    Senior Member readeral's Avatar
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    Follow up on the taste of that Brazil roast - after 4-5 days rest, the chocolatey smell coming from the bag was amazing! As espresso very smooth cocoa, in milk, milk chocolate and a little nutty. Quite nice!

    I roasted some Kenyan yesterday, very excited to taste it. Unfortunately I had to pull it early. The spring on the thermocouple I have, although happy to wrap over the side of the roaster, does not allow the turbo oven to rest entirely on the silicone tubing. So I'll be changing my thermocouple sooner than I might've intended... as the ramp and roast times I'm really happy with but my problem was that once the Kenyan hit 203, it stalled. I fiddled around with the placement of the TO a little bit and got it to 205, but I had to dump them out, cause I couldn't see it getting any higher. The result still seemed good though, very even roast, nice colour, smelled delicious.


    So - the thermocouple over the side would be fine with a TC like the one Andy sells. Has anyone ever tried using a surface mounted TC on the floor of the roasting chamber? I've seen a few screwed to the side, but I'm wondering if it might be easier/more accurate to measure the bean temp from a position that beans are permanently in contact with the TC? Getting a silicone mounted surface thermocouple would allow wrapping the silicone up to slip it through the holes in the inner chamber and place it on the floor of the chamber. Just a thought. I'll think it through some more.

    Some other things I'm thinking about:
    - Using the aluminium tray mod suggested by nikko.the.scorpio in his thread, on the underside of the glass, to help with those moments when big beans (like the Kenyans!) don't want to push out of first crack, and in general to limit heat loss/allow larger roasts.
    - Controlled repeatable way of increasing/decreasing airflow across the roast, either by slightly lifting the TO off the roaster lip with some mechanical process, or adjusting the way it interacts with the silicone tubing.

    - long term, it would be great to have some sort of mechanism to allow loading the drum without lifting the TO - but I think that's a long shot, would require welding, and tools and skills that I just do not have.

  26. #26
    Senior Member nikko.the.scorpio's Avatar
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    Al,

    Great build - it looks sensational, works very well and the quality is such that it should serve you for many years to come with scant items periodically replaced. Well done!

    Just a couple of very small suggestions:

    - I bought one of these from Ebay: 111597898626. Perhaps rather than over the lip of the pot you could go through the base of your outer pot and screw/silicone it into the inner pots base. You'd probably need to drill through your chopping board as well. Alternatively in through the side wall of the pot. Lots of options there, guess it depending if you're after the bean mass temp (which I think is a bit stetchy to accurately gauge) or the internal roaster temp (which is easier to set a friendly probe position with). Lots of probe options out there so just depends which one suits where you're hoping to place it - but your current over the lip one really would cost you a lot of heat loss so I agree you need to change it ASAP.

    - As far as the aluminium tray mod to the inside of the roof of the TO. I think it's of marginal benefit so if you do it don't do nuts or too perfectionist about it. I think they say generally 40-50% of the heat is lost through the roof/top of most homes so lets assume this is the same for the oven's environment. When I use one of the uncovered TO lids I can see that the exposed glass that is WITHIN the inner perimeter of the pot is perhaps 20% maximum of the overall surface area - the vast majority being the central section of the TO. So if you say insulation saves 50% of that heat then it's 50% of 20% of 40-50%. So perhaps 5% heat saving available but thats prolly being very generous. But it's easy enough to do so see how you go. Best case I'd say would be reflective insulation like foil on the interior and then insulative stuff on the outside (like some doubled over fire blanket etc). But again I think this is all 'luxury' stuff that really won't make much difference to your end roast.

    - I think the opinions on 'burping' the TO to decrease the internal temp are pretty mixed, but lifting the lid off for a set time period would be pretty repeatable in terms of the actual effect it has on the internal temp. So when you combine that with the fact you have a live graphical feed of the internal temp you should be able to get good repeatability. I personally prefer to just drop the TO's temp but either way should work to slow/decrease the temp.

    - I see what you're saying about the way to load the beans without opening the TO and you're right I can't see a way to do this without welding or something tricky mechanical. But again I feel this is perhaps complication for little real benefit. As if you're preheating the roaster I don't feel this is a critical part of the roasting cycle were a heat loss (and I find you can dump the beans in very quickly <2sec using an old 2L plastic icecream container that you squeeze to make it angle into a good pouring vessel) is potentially a real issue - like if you stalled it just prior to first crack etc. So I would think you can get better improvements for less hassle improving other aspects of your roaster.

    Again your roaster looks great - haha and seriously I think those bigass legs on it really are winners. Special credit to Mrs Readeral for not only sewing one great looking heat blanket mod but also for soldering!!!!

    BTW what espresso machine & grinder are you pairing this with? Is this your first forade into home roasting or have you used other methods previously? Great build anyway....I'm very impressed.

    PS. Have you loaded up buying green beans for your new toy yet? If so what'd you get or what are you planning on getting?

    Wish I could buy more myself as would like a few blenders/base beans but have around 12kg onhand and from what I've read it's best to consume within 12mths and that alone will take me a year to get through (at 500g every fortnight).
    Last edited by nikko.the.scorpio; 13th October 2015 at 01:23 PM.

  27. #27
    Senior Member readeral's Avatar
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    Thanks for the kudos and suggestions Nick. Angie has been great with helping me with my build! Marrying an engineer was a great decision. She's been a great sounding board, and helped me understand DC motor theory enough to make decisions around that.


    I think from here, any drilling etc. for improvements will be done as major surgery, so any little things would wait till then. That means no probe drilling for now. However with insulated pots and almost 5cm of wood base, through the side would've been my only option.
    The probes available through Bean Bay don't have the spring on the end of them, just a cable, which I could easily get over the lip of the pot between my cut silicone tube without causing measurable heat loss, as it'd sit below the thickness of the silicone. The other thing I'm keen for is a 3mm probe, as the 5mm is too slow to respond (I found a graph somewhere that showed the response time of ungrounded thermocouples to their relative diameter, 2mm makes a huge difference!) and Andy's is 3mm.


    My biggest concern is not accurate temperature readings per se, but precision. Consistency of environment and predictable repeatability, so, benchmarks that I can hit consistently that give an excellent result in the cup. I'd like to limit as many variables as possible - as the variability of the beans themselves is enough to deal with! I'm sure for most (eg. Ex-coretto users like yourself, ex-popper users like me) the closed environment would seem like a gigantic leap in consistency - and it is! - but having friends that are commercial roasters in Tasmania and talking through theory and practice with them (coupled with my over enthusiastic scientific bent) makes me eager to take what is already a great KKTO design, and find how I can make it as controllable as possible. So in a sense, I'm not fussed whether my probe is measuring bean temps accurately (there's always that person who points out that your probe isn't inside a bean!) but consistently. However, a more sensitive probe (3mm over 5mm) will allow me to see minor changes to the system that would have otherwise been smoothed out by the heat retention of the probe.

    I'll definitely be looking at installing an ET probe as soon as I decide if I'm going the TC-4 direction, or another (as my DMM only takes one input).


    So, why things like the aluminium shielding appeals is because it may help with mitigating against weather changes. Having a consistent way of loading the beans means limiting ET changes as a result of loading variables (eg. Getting tangled up while pouring in, higher charge weight resulting in taking extra time to get the beans in etc.). Being able to hit my turning point at the same temp every time for my bean profile (once I'm onto a winner), so that my RoR is consistent. Things like that.

    Rather than lifting the TO for airflow changes, I thought maybe retrofitting something similar to item no 321574202808 (obviously not this one... but conceptually, think of a hand operated airflow valve with 'stops') to change the airflow might be an interesting thing to think through further. Maybe something for the next 6 months to mull over. I don't pull the trigger on things quickly.

    Re pairing with machine
    This is not only my first foray into roasting, but my first foray into home espresso at all. I started building this KKTO even before I'd bought my first espresso machine!! I wasn't flying blind though - my neighbour (adifoto) lent me his Silvia for a month while he went home to Romania. My acquiring of a popcorn popper for mucking around with was less than a week before I started committing to the KKTO build, so I can't say I've had much home roasting experience. Done more in the KKTO in the past week than I ever drank from my popper.

    My machine, which I've had for about a month, is an ECM Technika IV Profi. I bought it from Jetblack Espresso and they were fantastic. Unfortunately it's paired with a 6 year old Sunbeam Cafe Series grinder, which patiently ground 6 years worth of French Press on the promise of a coffee machine... that never eventuated (bought a freaking expensive drum kit instead...). So all my raving about consistency further up.. yep. The grinder is frustrating me no end. Waiting for someone to sell Super Jolly-E here, or will pick up a Macap M4D in the new year. I've never worked in a cafe, but some of my best friends are baristas and roasters, so you could say that it was an inevitability that I'd succumb to the bug.

    So, for cupping my roasts (which I did some of yesterday) I'm using a ceramic Hario grinder, just to ensure I'm able to set a grind setting on a second device that I'll never change. Consistency

    Re green beans
    Green Beans I've been getting from elsewhere in greater western Sydney, (not Beanbay, despite putting an order in on Beanbay this afternoon...). Cost/kilo is slightly higher, but shipping is lower, and I have the flexibility of buying 1kg lots to get a sense of different beans from different regions. At the moment I have (or have tried):

    - Sumatra Lake Tawar
    - Colombia Popayan Cauca Supremo (almost all out)
    - Brazil 'Toffee' Cerado (all out)
    - Indonesia Bunisora Honey processed
    - Guatamala Finca Ceylan Organic (all out)

    - Brazil Daterra RFA Bruzzi (all out)
    - Ethiopia Sidamo Chire Gr1 Natural
    - Kenya Kagumo AA

    I think I'll be getting a stock of the Brazil Daterra (milk chocolatey, quite delicious), another Colombia, another Guatamala, and I'll decide between the Kenya and Ethiopia which one I want a stock of, probably Kenya as I'd like to get some Ethiopia Harrar Longberry.
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  28. #28
    Senior Member nikko.the.scorpio's Avatar
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    Great post 'Al - well please post any little tweaks you make to your roaster. Understand completely where you're coming from with the controllable consistency etc - absolutely makes sense. Sounds like you're just a matching grinder away from Coffee Nirvana - should pop yourself up a WTB ad as you know it'll drive you nuts if the perfect one comes up but someone beats you to the punch plus you know there's LOADS of folks here just itching to upgrade their gear but too lazy to list them so your ad would be a godsend for them. :-)

  29. #29
    Senior Member readeral's Avatar
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    Haha thanks. I'm a bit OCD about it. I was just saying to Angie that at the end of all this, I won't have hit the consistency I'm after - but I will have learned a heap. And hopefully will have been able to add back into the R&D that has made the KKTO such an impressive roaster.

    Good idea with the WTB - will try to convince the Mrs. It's easier to persuade *ahem* purchase something when being an opportunist :P

    I was also thinking re: the aluminium shielding. You really want to avoid any heat returning to the glass, as although the amount of glass in contact with the inside of the system is small, the remaining surface area of the glass with which to transmit that heat into the outside environment is still 500 square cm or so. With aluminium shield, the air trapped between the aluminium and the glass will act as an insulating force as well. Even if one gains 10% efficiency, that's 10% more beans you can get into the roaster with controllable results

    What beans have you got in your stash?

  30. #30
    Senior Member readeral's Avatar
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    Wow just tried my Kenyan as an espresso. Blew my head off with it's brightness! First pour was too fast, so I ditched it (had a bit of a taste, but knew it was bad) - second pour I could smell the fruitiness of it, smelled delicious, and went down quick. Good acidity. Now I get why they say '10% African in blends'.

    Needless to say neither my roast, nor my grinder has done this coffee any favours. Hopefully tomorrow it pours even more tastily. Can't wait to have another go at roasting this gem.

  31. #31
    Senior Member nikko.the.scorpio's Avatar
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    Quote Originally Posted by readeral View Post
    I was also thinking re: the aluminium shielding. You really want to avoid any heat returning to the glass, as although the amount of glass in contact with the inside of the system is small, the remaining surface area of the glass with which to transmit that heat into the outside environment is still 500 square cm or so. With aluminium shield, the air trapped between the aluminium and the glass will act as an insulating force as well. Even if one gains 10% efficiency, that's 10% more beans you can get into the roaster with controllable results [/QUOTE
    Fair point and as I've said from the get go it's not overly hard to put the tray in place (unless you're looking for aesthetic perfection) so should only take ~15mins (not including any gueing on the inside). Cost is also very low ~$3 so worth doing from several perspectives.

    What beans have you got in your stash?
    I've currently got a couple of kg of the following:
    Ethiopian Gambella Sundried
    Panama Jaramillo SHB
    Peru Ceja de Selva AAA
    Sumatran Mandheling Jade

    Also around a 1/2 dozen <1kg scraps from previous bean buys. Try to go with 3-4 beans per roast along the rough KJM Blend type guidelines. Keep a very basic log of the batch but it's pretty spartan in detail. Don't mind that I don't ascertain much from it in this regard as I look at the varied combinations of beans as part of the fun of roasting - kind of a lucky dip but I've never had any be poor.

    I've historically ordered the lower mid range beans as I didn't find the more pricey ones made much difference in the cup (or could just be the entry level ones were very good!) - IMHO blending is definitely the way to go rather than SO's. And blending is where an expert can turn a good coffee into an unbelievably fantastic coffee......I don't profess to have any great prowess but try to balance out using the KJM template. :-)

  32. #32
    Senior Member readeral's Avatar
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    Yeah so my Kenya, Ethiopia aren't the cheapest on the shelf, but they were the cheapest africans in stock at the time :P Aside from the Brazil Daterra, the rest were all what came in a sample pack, and the Brazil was definitely worth its cost. Gonna be picking some more up asap as it's deliciously sweet, send some to my brother who "doesn't like coffee".. He'll like this one

    I wouldn't necessarily buy a bean because it's valuable - I think you're right, you can be totally satisfied with the less costly beans. It's unlikely I'd get all the potential out of roasting expensive beans right now. But one thing I would happily pay a few dollars per kilo more for (but thankfully one doesn't always need to...) is good graded coffee. Well graded beans are the ones that have given me the best, most consistent results as an amateur.

    I've done a little pre-blending in my popper, but had no idea what I was doing, so the result wasn't great. Also it was popper so the result wasn't great... :-/ I think at this point, my preference is for cupping each coffee individually, learning about its flavours, seeing if I can get some consistency from my roasts, and then from there start thinking about post-blending with various ratios till I find something I really enjoy. I'm totally happy to blow my own head off with SOs with high acidity, I've had many an african espresso in my time, and quite enjoy the ride.
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  33. #33
    Senior Member readeral's Avatar
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    So a very slight modification to my build.

    I purchased from Andy a 3mm thermocouple, and have installed it exactly where I had the last one.

    What I've done is purchased some 3mm fibreglass sheathing (rated to 450 degrees apparently) from Jaycar, and placed two layers of it over 95% of the thermocouple length. I pulled the spring from the top portion of the TC cable (came away easily) and so now the thickness of the cable will not inhibit the turbo oven. I've mounted the TC with a small plate behind so that the entire length sits away from the wall of the chamber. I've also ensured that it sits 5mm above the bottom of the chamber.

    So the thermocouple is basically entirely isolated from the chamber itself because of the fibreglass, except for the point where the cable touches the lip of the pot.

    The hope is that although the thermocouple will be subject to ET prior to beans being added, and so the length of the TC will still heat up, that it won't struggle to drop in temperature when beans come into the system like it might have if it was in direct contact to the preheated chamber. My previous 5mm thermocouple did not respond to temp drop sufficiently, bottoming out at 140 degrees, as the chamber itself retained a lot of heat (a good thing!!) but being in constant contact with it, I was fighting a losing battle. I'm also hoping the change will give me a little better accuracy in the bean temps as it climbs again, rather than chamber wall temps. Entirely granted BT is a combination of air temp, bean surface temp, airflow etc. (gosh imagine a tiny burn proof Bluetooth temp sensor. Give em 5 years.)

    Here's a photo or two ImageUploadedByTapatalk1444980596.311240.jpg ImageUploadedByTapatalk1444980619.021546.jpgl
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  34. #34
    Senior Member readeral's Avatar
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    I'll need to work out a better way of mounting eventually, as this collection of bits and pieces will accumulate cruft.

  35. #35
    Senior Member readeral's Avatar
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    Well as much as I might have a fancy looking KKTO, I absolutely haven't tamed the beast yet.

    I'm feel like a total rookie, and without someone much more experienced roasting beside me and giving me feedback, it's definitely a frustrating experience. I think out of all my roasts, there has only been two that I've been totally happy with (ironaically my first two listed in this thread!), and some that have been 'fine'. I drink (almost) everything I roast though. The only exception was an especially old and dry brazil that I tried to roast I threw out cause it really wasn't suitable for roasting in the end.

    Part of the trouble I think I'm having is because the turbo oven is just so sensitive to change, being fan forced AND a halogen element, that the pulsing of the element makes the temperatures hard to control. Preheating properly should help me mitigate this issue, but I don't feel like I've found the right pre-heat temperature yet.

    It's also evidently remarkably hot at times I think. I'll end up with underdeveloped roasts that seem plenty dark enough - and sometimes also quite uneven, which is even worse. I think I need to start quite gentle, and then ramp up, and not be too scared to let the roasts exceed 20 minutes.

    (The other thing I think that is impacting my roast is the spring that I added. I'll be removing that soon, because I suspect it is still pushing beans around a little bit, not helping with the unevenness)

    I've been consistently trying to roast 600g - I'll be dropping down to 450 or 500g with my next efforts I think, to see if I can master the lower weights before trying to increase again. Any insight y'all can offer me (especially you Nick!) would be great!

  36. #36
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    I have only done the one roast in mine so far, and it was about 400g.
    I think the roast time was around 20 minutes, but I didn't really time it. I just watched it until it hit the right colour for me. I also didn't preheat it, but let it heat up from ambient with the beans.
    2 days later, and the beans smell superb!
    Don't give in. You will hit on a system that works for your taste, and once you have it, then you will be set.

  37. #37
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    I think with a KKTO Roaster, even though it's not absolutely necessary, consistent roasts (and therefore results in the cup) benefit from preheating such that the internal temp is between 130C-150C and stable before you drop the beans in.

    A significant portion of the roasting in a KKTO is achieved by conduction with the sides and bottom of the vessel as well as convection and radiation from the TO itself. You're basically looking for a Turning Point of between 60-80C, so adjusting the batch mass and the TO heat setting may need to be juggled to get this.

    As mentioned at the beginning, there's no need to go to these lengths but it will help in getting full roast development of the bean, and consistency in the cup.

    A lot of people, of course, choose to go the simple path and use the KKTO as a set and forget kind of roaster, which it can do quite well; some of nicest results in the cup I have enjoyed, have been from a KKTO used in this way. All in all, I think the KKTO offers the best of both worlds, depending on how far you want to get into coffee roasting at home.

    Some TOs seem to have a wide dead-band temperature controller and it seems that you may have 'lucked' on to one of those "readeral", unfortunately. I do know of a few KKTO users out there who have modified their TOs with a better type of controller but can't remember the details. Maybe one or more of them will chime in with some advice....

    Mal.

  38. #38
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    I have a modded KKTO using a Steinel HG2300 heat gun fitted to a stainless steel top,shown in previous thread. By using 66% of available cyclonic airflow my main roast is 625grm of greens from ambient ,with full heat the roast takes 15-17 minutes to complete to CS9 @224deg.With my setup I have completed 1125 grm roast in the KKTO.My suggestion to you is to increase the batch size and let the beans roast them selves.Green beans will only use the heat they need to roast as Koffee Kosmo and I have agreed upon.

  39. #39
    Senior Member readeral's Avatar
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    Quote Originally Posted by Shano592 View Post
    Don't give in. You will hit on a system that works for your taste, and once you have it, then you will be set.
    Haha Shano, don't worry, I have absolutely no intention of giving in! Given I've nailed a few roasts, I know my built is capable so it's just a case (as you say) of getting the operator comfortable on a repeatable approach

    Quote Originally Posted by Dimal View Post
    I think with a KKTO Roaster, even though it's not absolutely necessary, consistent roasts (and therefore results in the cup) benefit from preheating such that the internal temp is between 130C-150C and stable before you drop the beans in.
    ...
    A lot of people, of course, choose to go the simple path and use the KKTO as a set and forget kind of roaster, which it can do quite well; some of nicest results in the cup I have enjoyed, have been from a KKTO used in this way. All in all, I think the KKTO offers the best of both worlds, depending on how far you want to get into coffee roasting at home.
    I think you're right here Mal. My best roasts have had a fairly high preheat (150-200 degrees) but I stopped preheating that high to try and avoid the tipping I was getting. But now I think about it, it was only the overly sensitive brazil green I had that was tipping with a preheat... possibly by lowering my preheat is causing more trouble than it solved.

    I was thinking last night that possibly the element-style TO (remarkably hard to get now! Found one at JB-HiFi for more than I was willing to spend) is more desirable, despite their lag in responsiveness, given that the element remains hot while it's not receiving current. The glass halogen element can cool down almost instantaneously, so relying on circulating existing heat in the system - making paramount the importance of the pre-heat! I know this because the fluctuations I'm getting on my bean temp probe (one of Andy's, its definitely accurate - I test it often) can be pretty wild. So I think you're right on the dead-band comment too - will try a different model TO in the future.

    A significant factor in my failed roast last night was that I tried roasting in Tasmania, not NSW, and my outdoor temperature dropped 10 degrees across the 20 minute roast. Learned my lesson - roast in the mid-morning/early-afternoon when in the south :P

    I know a fair amount of roasting theory for a rookie, I have a bunch of friends that roast commercially and we talk about it often. Also, the internet is a wonderful place, and I _think_ I know enough to filter out the rubbish. Obviously the problem is that I need to better learn my roaster to apply that theory - and what I'm just not going to be able to achieve with it - and also how it responds to environmental changes. One can learn to make coffee quickly, as you're able to make 2-3 a day. Roasting takes a lot more time unless you're perfectly willing to roast up 5kg of beans that you'll likely not be able to drink.

    I'm definitely not a set and forget fellow - I'm keen to roast to the benefit of getting the most from a bean, just need to work out how best to control this beast! So I think I'll return to my 175 degree 20 minute preheat, which usually gives me a turning point of around 60, and this will also reduce the number of step ups I'll need to take to increase my temperature across the roast - which will hopefully be a lot more consistent for me.
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  40. #40
    Senior Member Bosco_Lever's Avatar
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    Simplicity is the key.
    Follow the teachings of KK.
    Preheat at 250C for five minutes.
    Tip in at least 650g of green beans.
    Let the TO do its stuff at 250C. Tip at cusp of second crack, or slightly into it.
    Perfect results.
    Burping is only needed for SHB varieties. Once at first crack, and again, 2 minutes later. I only do this for Kenyans, Yemen and Costa Rican beans. All others including blends are left alone.
    The trick is to work out the capacity of your roaster, and adjust your technique accordingly.
    Playing around with temps is a waste of time.
    I followed KK's advice and have had great success. The only bad roasts were due to me becoming distracted and not ending the roast earlier. Even then, the roast was very good, just with some roast flavours becoming prominant, but no ashy taste.
    KISS is always the best approach.

  41. #41
    Senior Member readeral's Avatar
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    Depends what you mean by "best" and "perfect results". I've followed such an approach and it hasn't yielded results that I'm entirely happy with. Probably in the 'fine' category for some beans, and some beans ended up with charring or very roasty flavours, so there are more variables than temperature and time to consider. Maybe you roast in a closed environment, I'm not sure, wasn't part of your KISS explanation. I don't like to roast as dark as the cusp of 2nd - even though that's the most popular depth around here, so I need to be more careful with my development phase and know when to pull.
    At the moment I'm documenting everything. I'd sooner know how to tweak a roast to get the best out of a bean. But I'm still green to this game yet.

  42. #42
    Senior Member Bosco_Lever's Avatar
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    I roast in the garage with the door open and adequate ventilation. I do not use a fire blanket. Ambient temp is 22 to 24C.

    Your issue (putting it simply and diplomatically) is that you are complicating matters.
    Choose one bean, say an Ethiopian, and follow the above method.
    Start with 650g, then do the same with 700g, 750g, until you find the sweet spot.
    Forget about the length of time of the roast. Just do it and taste.
    You will find which load is best.
    This is what KK recommends, and my experience concurs.
    I do not get any charring or roasty flavours unless the roast goes into rolling second crack territory.
    You need to maintain the temp at 250C, and adjust the weight of beans.
    You went to the extreme when building your unit, to stop heat escaping, and can probably do 1kg roasts with no issue. Your problems stem from too small a load.

  43. #43
    Senior Member Bosco_Lever's Avatar
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    Quote Originally Posted by readeral View Post
    At the moment I'm documenting everything. I'd sooner know how to tweak a roast to get the best out of a bean.
    Before you can tweak a roast, the roast has to be drinkable. Tweaking it is by bean weight.
    You are trying to run before you walk.
    Concentrate on one bean, and learn what your roaster can do at different weights.
    Once you have mastered this, you can tweak the roast.

  44. #44
    Senior Member Koffee_Kosmo's Avatar
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    The KKTO roaster was designed to handle larger loads It's designed to roast loads of 650 grams to 750 grams and above ( roaster chamber volume setting dependent )
    Yes it can roast smaller loads but heat control needs to be monitored carefully and check that agitation is also adequate for complete mixing

    Also One mans profile using XYZ roaster will not result in the same roast on another roaster Only automation and control of heat source will get close

    KK
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  45. #45
    Senior Member readeral's Avatar
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    Yeah so that's what I think I was pushing back against KK - I'm not convinced that (for example) my KKTO wants a 250 degree 5 minute preheat, cause my RoR after loading at that temp is upwards of 30 degrees/minute. My best experience has been a preheat to 150 degrees, but with the whole roaster stable at that temperature.

    Absolute statements like "X approach is always best" gets my back up. I'm sure my roaster will behave differently to others.

    I'm hearing you on the charge size Bosco, and I appreciate the suggestion - I'll increase the charge to 800g and I'm sure I'll get a much more evened out roast given what you've said - but I still want to know what's going on, and I wouldn't say that keeping records means I'm trying to run before walking. Incidentally, I'm still putting 600 grams in, it's not like these are disastrously small batches or anything. In my conversations with KK and then with other KKTO owners, 600 grams seemed a reasonable starting point, and my method was learned from the info I received from KK. KKs documentation recommended starting with 450g charge, and my starting point for method was as follows (verbatim):

    Coffee Roasting Method 2 - Roast from hot start
    A Digital Multi Meter can be used for accuracy if a specific drop in temperature is wanted


    o Pre heat the roaster at 200 deg Celsius for 5 minutes or until all surfaces of the roaster are hot
    o Start the roasters agitator
    o Add green beans to hot roaster or a pre determined temperature
    o Roast in set increments of temperature settings:
    - Start at 200 deg Celsius on the dial for up to 2 minutes
    - Increase heat to 220 deg Celsius up to 6 minutes
    - Increase heat to 250 deg Celsius to first crack
    o Only reduce heat after a rolling first crack and to facilitate a longer time to second crack
    o Aim to reach second crack in the range of 6 to 8 minutes after first crack
    This was a great start for me - I learned a lot about it's behaviour, and I guess my next step is to increase the charge weight.
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  46. #46
    Senior Member readeral's Avatar
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    Ok so tonight I roasted 750 grams of a Brazil bean. 15 degrees outside.

    Preheated to a steady 150 degrees. At charge I upped the temperature to 200, at 2 minutes to 220, and at 6 minutes to 250 (you can see this knee in my graph, but it was right on the cusp of the development stage, so I wasn't too worried) - from this point on I didn't touch anything. I had a turning point of 63.3 degrees 1:10 into the roast.

    After hitting around 170 degrees in bean temp, the RoR took a small dive - makes sense, the TO had started to heat the drum again as well as the beans. It recovered a little before continuing it's slow downward progression.

    The RoR increased (as expected I suppose) at first crack, but by this point I was teetering on the edge of a RoR of 1.5 degrees/minute so wasn't inclined to play around with the dial - but I should have because it rose up to 3 degrees/minute and plateaued there almost until I dumped the beans at 212 degrees at 26 1/2 minutes.

    Here's my graph:


    So the result? Well sure it was a much more even roast - I put that down to the increase charge weight (probably) allowing beans to experience a full range of exposure. But I still have tipping (or is it scorching - I'm not sure. Basically overdone right at the tip of the bean). Sorry, no pics, no natural light to photograph and I've bagged them all up.

    So where does this tipping come from? Too high a charge temp? An uneven mixing action? Hot spots on my roasting chamber? Too high MET? I'm not sure. Maybe a combination of all of them. It's not only a few beans, although not being all it does permeate the roast - so I suspect it's possibly a temp of drum issue, but in that case I'd have expected to see scorch spots on the body of the bean as well, which I'm not.

    It might be from the increased RoR at the end there, but I was having a look into the chamber as best I could, and I thought I saw it appear before that flick at the end.

    The greens are fine - I took delivery of them 2 weeks ago. Haven't got a density measurement, but I'm sure they're not dry.

    Part of me wonders that if I had a solid agitator, I'd be able to toss the beans around a little bit more like a traditional roaster and so better move them out of contact with each other and the drum. I don't know. I'm also wondering about airflow - maybe my TO doesn't extract as much air as some of the older models that snobs are using. So many variables - probably barely any of them matter - but I still need to solve my tipping issue.

    Anyone who has experienced it in a KKTO and successfully resolved the issue is particularly welcome to comment, although ideas from anyone would be great.

  47. #47
    Mal Dimal's Avatar
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    Some good info to be found here and in other articles in and around the website mate...

    http://www.roastmagazine.com/resourc...RoastGetIt.pdf

    Tipping.JPG

    Mal.

  48. #48
    Senior Member readeral's Avatar
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    Thanks Mal. I've read a few of Boot's articles floating around, although he does keep his cards close to his chest, his roasting defect articles have been great, so it's handy to be pushed back in that direction for some much needed revision. Chatting to a mate at a cafe down here confirmed my thoughts about reducing charge temp so I'll give that a go next roast.

    I know it's dangerous to question the status quo, but I'm going to float an idea anyway. This is only a thought experiment presently, and far too impractical to do anything about right now.

    I received Rao's book on roasting for Christmas (if you are reading this and want to bash the book, I'm not interested, sorry. Do that in another thread) and been enjoying his fleshing out of my skeletal knowledge. One thing that intrigued me as I was reading through his description of various roasters was his explanation of the "Classic" drum and double drum designs. The KKTO strikes me as (forgive the comparison) being as close to a double drum in physical build as any other "traditional" roaster. However this description falls down as the method of heating the whole chamber is entirely not like a double drum, but the heat comes directly to the beans, more like a fluid roaster.
    Rao gives some pros and cons (and any other observant roaster could tell you the same) that the downside of of the classic drum is that overheating the metal "can easily lead to bean-surface burning".

    I was heating my roaster quite high (to a stable temperature, not a few minute burst at high heat) in order to try to generate more conductive/radiant heat to balance the convection airflow, and reduce the amount of energy going into the roaster's metal during the roast, rather than the beans. In doing so carelessly, I was gaining all the downsides of the classic drum design, without its indirect heat benefits. So... After that long winded fluff, I'm thinking of what the impact might be of preheating the outer pot of the KKTO, without the roasting chamber inside, and "charging" the roaster by inserting the chamber quickly with the beans already inside it, thus gaining the benefit of the radiating heat from the already preheated chamber, without the downside of room temperature beans being poured directly onto a 150-200 degree surface and tipping/scorching, mimicking somewhat the way a traditional roasting chamber will quickly make the beans inside it airborne, avoiding the same issue. Anyway - just some thoughts to mull over!

    To be practical, a KKTO roaster really wouldn't be able to manage the (stable) high charge temps that traditional roasters manage without some sort of roasting defect.

  49. #49
    Mal Dimal's Avatar
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    Worth a try mate....

    With a Corretto for example, there is absolutely negligible benefit to preheating the Bread Pan, as the thermal mass is so low that the bean mass, once introduced, brings the temperature down to just above the bean mass temperature after introduction.

    With the KKTO, there is much more thermal mass available, so the concept of post introduction of the beans to a preheated roaster, does make some sense. It's been a while since I was able to play around with a KKTO so I can't remember what the Inner Bowl mass was, I don't think it was all that much but it should be able to buffer the 'rate of rise' of the bean mass enough, such that you should be able to avoid tipping or scorching.

    Will be interesting to read how you get on...

    Mal.

  50. #50
    Senior Member Koffee_Kosmo's Avatar
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    Behmor Coffee Roaster
    Technically speaking the most descriptive design features of the KKTO is
    Heat = Forced Fan " Convection"
    Roast Chamber = Would be closest to a "Packed Bed" design ( without the turning bowl & agitator used instead )

    I have conducted many many trial experimental roasts and most turn out good To be on topic with drop in heat temps I have experimented with Cold drop - works equally well with small and medium batches producing a slightly longer roast but with full body flavour
    So the method is Drop in cold Turn on the TO to 250 C and only turn down only " if required" after first crack

    Some KKTO builds may be more thermaly stable than others so the owners need to make small adjustments to suit ones own roast style and eventual taste they are trying to create
    There is no right or wrong Keep in mind that the key things that make this roaster work so well is
    1) Roaster Chamber Volume
    2) Heat - Convection type - and with preferrence to the 1400 Watts models
    3) Agitation - good constant mixing "Like a Rolling Stone" agitation - not a large mass of beans pushed around the roast chamber ( It took me a few months to get this right so agitation is very important ) Refresh and adjust agitation as needed by visiting the YouTube videos I have posted - there is one for a double solid blade with springs, and also one with the early model wire style

    Hope that helps
    KK
    Dimal, Shano592 and readeral like this.



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