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Thread: Turbo Oven

  1. #1
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    Turbo Oven

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi, Great forum and I am looking at doing a home roaster based on Koffee-Kosmo plan. (fantastic idea)
    I purchased a Homemaker Halogen Turbo Oven from K-mart and here is my concern.
    I have not been able to get the oven up to temperature. (it switch on and off which is apparently normal)
    When its set on 250 deg c and with a temperature probe touching the metal perforated plate it only records 230 deg c
    If I just measure air temperature it only records 215 - 220 deg c.
    Testing has been done in an insulated aluminium frying pan that is fairly well sealed and approximately 6 cm in depth.
    I am not sure if this is strong enough to roast coffee ?
    Will the air circulating as per KK plan increase the temperature ?
    Can any simple modification be done on the Turbo Oven ?
    Thank you

  2. #2
    Mal Dimal's Avatar
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    Welcome Pm...

    Probably better to ask about this under the "Roasters" category, where plenty of KKTO builders will see it...

    Mal.

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    Okay thanks.
    I will re-post in that category..
    John

  4. #4
    Senior Member flynnaus's Avatar
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    Quote Originally Posted by Postmaster View Post
    I am not sure if this is strong enough to roast coffee ?
    Will the air circulating as per KK plan increase the temperature ?
    Can any simple modification be done on the Turbo Oven ?
    I have been using a KKTO ever since the beta release back in 2010. At first I had problems with temp and roasting times were long - sometimes as long as 25 mins. I'm now up to my 4th turbo oven but my roast times are usually 15 - 16mins. The mods I have used are high temp silicon rubber tubing to seal gaps, a fire blanket for insulation and, at one stage, a metal plate to reduce the volume. The biggest difference to roast times has been pre-heating the oven before adding the beans. Other have used mods to insert additional heat such as electric frying pan bases or drilling holes in the heat shield of the turbo oven to increase air flow.

    I don't think your temperature measurements will give a proper indication of the effectiveness of your turbo oven. You really need to measure the temperature of the bean mass.

    As Mal suggests read through the Roaster posts on the forum. Use the Search function to search for KKTO. Here's one thread:,
    http://coffeesnobs.com.au/roasters/3...en-issues.html
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  5. #5
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    Thanks flynnaus, I have and still having a look through the Roaster posts on the forum. Its has some great ideas and information. What you have mentioned about the temperature of the bean mass makes good sense as they would
    naturally hold the heat.
    Once again tks
    John

  6. #6
    Senior Member nikko.the.scorpio's Avatar
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    Postmaster, in short your concerns are completely unfounded. KK style builds are many and varied and unless you have a very badly sealed roasting chamber or are using something completely unsuitable (a 6cm deep pan isn't going to work well at all in terms of allowing chaff removal etc - but you;ll have no issues getting it has hot as required) temperature is NOT an issue with any TO's I've encountered.

    I have my own build thread but I recommend you refer to the one done by Readeral.

    Do things vaguely correctly and temperature will definitely not be an issue. :-)

  7. #7
    Senior Member readeral's Avatar
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    I have a Kmart Turbo Oven - and I definitely don't have temperature issues... well, not ones where it doesn't get to temperature. What I _do_ have is temperature control issues - in that I'm sometimes scorching beans due to too much energy! (Flynnaus, any wisdom on this would be grand).

    You will be fine with your turbo oven unmodified, I promise. The suggestions of flynnaus like silicone hose, fire blanket and volume adjustment are all things I've implemented on the back of the collective efforts of many in this forum.

    That being said - given how cheap the TO was, I suspect quality control is very low - and it could be that my TO is overpowered, and yours is not.. but you'll only know it if you use it in situ. Build a KKTO and see what happens :P If you need a new TO, then just return it to Kmart suggesting it doesn't hit it's 250 degrees and they'll replace it, but my Kmart one is perfectly adequate.

    Also, I don't think the username is supposed to be Postmaster, surely that's just from when the posts were moved to the right place?

  8. #8
    Super Moderator Javaphile's Avatar
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    Quote Originally Posted by readeral View Post
    Also, I don't think the username is supposed to be Postmaster, surely that's just from when the posts were moved to the right place?
    As usual the nick was not changed when the thread was moved.


    Java "Change what?!" phile
    Toys! I must have new toys!!!

  9. #9
    Senior Member readeral's Avatar
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    Quote Originally Posted by Javaphile View Post
    As usual the nick was not changed when the thread was moved.


    Java "Change what?!" phile

    Will John see these replies in his notifications?

  10. #10
    Senior Member flynnaus's Avatar
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    Quote Originally Posted by readeral View Post
    ... I'm sometimes scorching beans due to too much energy! (Flynnaus, any wisdom on this would be grand)
    Scorching means too much heat is being applied. Without knowing your roasting methodology or your set up, I couldn't advise. The bean type could also be a factor.

    I can tell you what I do. My tried and trusted method is to pre-heat to about 160 degrees. Add the beans and try to maintain a 10 degree/min rate up to first crack then 3 - 5 degrees from first to second crack. I always stop my roasts on or just before second crack. I control the temp via the controller on the TO to maintain the 1odeg/min ramp (+/- 2 degrees)

    I use a Coffeesnobs DMM with a k-type probe inserted through the side. My batch size is always 400-500 grams.

    It had some scorching on some Maui Mocka beans last time so I think a softer lowland bean will need a gentler profile.
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  11. #11
    Super Moderator Javaphile's Avatar
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    Quote Originally Posted by readeral View Post
    Will John see these replies in his notifications?
    If he doesn't it's not because of any Moderator action and seeing as he's responded to this thread since it was moved he clearly knows it's here.


    Java "See what?!" phile
    Toys! I must have new toys!!!

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    Thank you for the encouragement Nikko.the.scorpio. I have actually read all the threads from yourself and Readeral and I totally agree with you. I will emphasis again, what a fantastic forum.

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    Hi Readeral. I have actually read all your posts and well and nikko.the.scorpio and now tend to agree with you on that subject. In regard to the name I actually worked for Australia Post for 46 years and my designation was "Postmaster" before they decided to change the tile to "Postal Manager" so yes I do use that username.

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    Username is correct thanks guys

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    Yep no worries thanks have seen all the replies

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    Hi readeral, Can you suggest where I can get the silicone hose and what size do I need. Thanks

  17. #17
    Senior Member readeral's Avatar
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    Quote Originally Posted by Postmaster View Post
    Hi readeral, Can you suggest where I can get the silicone hose and what size do I need. Thanks
    Hey, I've PM'd you. Your username caught me by surprise! Postmaster is often the default name for mailing lists and forum admin (well.. in my IT experience! evidently not here..), and because you were new it was in italics :P So it totally threw me
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    Yeah it does generate a topic of conversation. Sorry about that and yes you are spot on with your comment. Some sites will not let you use that name. Thanks for the info.

  19. #19
    Mal Dimal's Avatar
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    Quote Originally Posted by Postmaster View Post
    Hi readeral, Can you suggest where I can get the silicone hose and what size do I need. Thanks
    G'day Pm....

    Yes mate, just head into a Supercheap Autos, Auto One or one of those sorts of shops and ask to be shown their selection of high-temp Silicone Hose/Tubing...

    Mal.

  20. #20
    Senior Member readeral's Avatar
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    Quote Originally Posted by Dimal View Post
    G'day Pm....

    Yes mate, just head into a Supercheap Autos, Auto One or one of those sorts of shops and ask to be shown their selection of high-temp Silicone Hose/Tubing...

    Mal.
    I've given him some eBay links. I did try supercheap when I was looking, but at the time couldn't get the right inner/outer diameters. Maybe Postmaster can better manage/has a better stocked store nearby

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    Hi Mal, Tried Supercheap. He said isle 7 and wasn't very helpful. But no luck there. Might try Autobarn or Repco tks
    John

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    Got those links thank you. I am in Echuca in Victoria, so stores do not carry a big range. I'll try Repco and autobarn and another auto shop, but I wont hold my breath
    tks
    John

  23. #23
    Senior Member sidewayss's Avatar
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    Hello Postmaster.
    If you dont have any luck with the silicone tubing, try the Koffeekosmo website and contact Paul.
    He may have them available or able to direct you.
    All the best and enjoy the roasting hobby.

    uploadfromtaptalk1448573734454.jpg
    This is a modification I did in order to do 1kg batches together with the fire blanket, plugging directly to the wall and pre heating the turbo before starting the roast.

  24. #24
    Senior Member readeral's Avatar
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    Paul has a heap of stuff on hand - he and I spent a few months talking it through, and I purchased some of his stuff. I recommend contacting him too.

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    Hello sideways,
    Thank you for your input. I will do the mod if I cannot get the correct temperature.
    The main thing is that I am enjoying the project.
    John

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    Hello readeral,
    Thank you for your input.
    The main thing is that I am enjoying the project.
    John

  27. #27
    Senior Member readeral's Avatar
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    Quote Originally Posted by Postmaster View Post
    Hello readeral,
    Thank you for your input.
    The main thing is that I am enjoying the project.
    John
    Hey John,

    I certainly hope you enjoy it! I did. The satisfaction of finishing was great. My thread has a bunch of stuff I wish I had planned/thought through before doing the build. Heed those, and hopefully you'll be spared my frustration!

    Cheers,

    Al

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    Hello Al,
    I have read your thread and I can see some of the frustration, but in the finish you got there. Well done. I am actually building this for my son. He can have the frustration and the learning curve to roast.
    My 2nd hobby is brewing beer. (and drinking it of course) I done this from scratch and have just designed a machine to malt my grain from scratch (an old front loader washing machine geared down to 20 rpm)
    This KKTO machine will also enable me to kiln a darker malt like a Brown Malt or Cara Malt (200 grams at a time) for a Brown Ale etc. I will post some pics when I have completed the project.
    Thanks once again for your guidance.
    John

  29. #29
    Senior Member sidewayss's Avatar
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    Roasted peanuts in them too. Turned out great after some salt added.
    Wont go back to packet stuff anymore.
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  30. #30
    Mal Dimal's Avatar
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    Quote Originally Posted by Postmaster View Post
    Hi Mal, Tried Supercheap. He said isle 7 and wasn't very helpful. But no luck there. Might try Autobarn or Repco tks
    John
    Ah, too bad...

    I think we must be over represented here in Warwick by petrol-heads then, as our local car-parts stores are chocabloc with every go faster, go harder parts you can imagine. Thought it would be the same everywhere...

    Mal.

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    Good luck with the roaster, Postmaster.
    I am gathering the parts for my own right now as well, having read through nikko's and readerals threads. A great list of tips and hints can be gleaned from their combined experiences.
    Just awaiting the final parts' arrival, then I can begin assembly. Hopefully it will be up in time for a Christmas brew.
    All the best to you.

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    Good Luck Shano592,
    Hope you are having as much fun as I am. This eliminates the frustration that can develop. I am doing something a little different to the pasta pot, but the same principles as the KKTO and basically without this thread and all the contributions by
    fellow roasters, I would never have attempted it.
    Good Luck again
    John
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  33. #33
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    Hi John,
    Yeah, I'm the same. I have been using a corn popper forever, but it is too slow to make a good-sized batch of roast.
    The info on this site has been really valuable. Once I get my version up and running, then I can hit up the site sponsors for for a large batch of green beans.
    Let us all know when you are finished with your machine. I for one would like to see your take on this design.

    Shano

  34. #34
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    How is your project going, @Postmaster ?

    I got mine done and gave it first roast today... about 400g of Jamaican Blue. I am impressed with the speed and even roast of the beans. I have read about it, but the experience of it is even more gratifying.

    While i was at it, I made a 20 litre bucket cooler, which is very efficient at removing heat from the beans.

    Many thanks to @Koffee_Kosmo, @Nikko.the.Scorpio and @Readeral for their insights, design tweaks and modifications. Their ponderings and changes of direction have doubtless saved me a lot of grief along the way.

    I also hit up the Bean Bay store for 5kg of beans. Looks like I will see them on Monday.

    Fun times ahead over the holiday period.

  35. #35
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    Behmor Coffee Roaster
    Here is the simple fix for K Mart Homemaker Turbo Oven.
    Had real trouble getting to reach 240 deg.
    Problem solved even using the existing stainless steel halogen cover.
    1. Go to your steel supplier and get the steel bands they use around steel to hold the packs together. Its about 25 mm wide and grey in colour. (They throw it out)
    2. Cut a strip about 30mm long by 10mm wide. The same size as the thermostat switch under the halogen globe.
    3. Drill a 4mm hole in strip. (Its needs a sharp drill).
    4. Undo the screw holding the thermostat switch.
    5. Insert the strip on top of the existing strip. (This is the one that heats and bends and open the points to switch off the halogen globe). I actually put mine between this metal strip and the cover holding the halogen globe.
    So I undid the 3 cover screws etc. A bit fiddly putting it back together, but got there. I think you should be able to insert it without going to that trouble.
    6. Screw the screw back in and away you go.
    7. Result 240 deg C easily. thermostat still works.
    Note this temperature was measure in air at the bottom of the pan.
    Hope this is of some help.



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