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Thread: Turbo oven issues?

  1. #1
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    Turbo oven issues?

    Cafelat Coffee Tamper and Accessories
    I have been using a KKTO for several years now and it has been working well

    The oven died so I got a new one.

    The new oven is a halogen one however it seems to turn on and off as if it is up to temperature from about 75 C

    It took over 30 min to get to 180 C

    Is it a dud oven or can this be typical?

    Is the an easy way to fix this?

  2. #2
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    The easy way to to check if it's going to work is to remove the guard and test it again.

    If that gives better results then have a look in the original KKTO thread for the modifications that have been done to the guard by other users.

    Here are the tests I have done on a couple of different brands I have used since I have been roasting, so far the Cookwell TO is the best.


    Gary
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  3. #3
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    Thanks for that.
    It is suprising the difernce the gard makes.

  4. #4
    Senior Member sidewayss's Avatar
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    Don, how are you taking the temperature reading?

    Turbo ovens in normal working order is up to maximum 250 degrees in 7 minutes or less.

  5. #5
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    I had a probe in the bean mass

    I changed the gard yeaterday (cut a hole in the middle and tuned it upside down) this made a big diference when empty.

    It worked even faster with no gard bit I would inagine the IR globe would be fragile.

    I will have to roast some beans soon the lot that were slow are not to my taste.

  6. #6
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    Tried it today 18 minutes for a roast all seems good

    see photo for mods
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    Just a query on the halogen roasters. Has anyone tried running a variable controller on one? I seem to recall that letting the temperature of the filament fall too low causes blackening, but I wondered about it in this context. The more rapid response than the resistive elements would seem ideal for variable control, but not if it kills the halogen lamp.

    Russell

  8. #8
    Senior Member Koffee_Kosmo's Avatar
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    After 3 years of faithful service my original Tiffany TO has been retired
    I now use a halogen type and find the light it emits is great for my ageing eyes
    The deflector plate mod is an easy one but I don't recommend full removal for safety reasons

    This photo shows my preferred method of modifying the deflector plate
    Drill 4 holes one in the centre and three others in an equal triangle pattern
    Refitting the plate upside down may be better but haven't tried it yet so I can't comment



    KK
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  9. #9
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    Tried had the coffee that I roasted yesterday it seems good.

    The oven did flick off several times.

    I found the light very orange in colour and so roasting to a colour was challenging.

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    KK,
    Does the mod with the holes really make that much difference?
    I have a Cookwell TO that is stock standard, will the holes make it work that much better to warrant playing around with it?

  11. #11
    Senior Member Koffee_Kosmo's Avatar
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    Quote Originally Posted by marke View Post
    KK,
    Does the mod with the holes really make that much difference?
    I have a Cookwell TO that is stock standard, will the holes make it work that much better to warrant playing around with it?
    I just got a highlander TO a year ago just as a spare on hand just in case the Tiffany broke down
    I find the light white and bright

    The holes allow a greater intensity and faster delivery of heat to the bean mass, this is fuelled by the force of the fan and I have observed that it is easier to roast larger green bean weights

    See the graphs above
    With the standard deflector I feel that the heat bounces back to the thermostat and causes it to actuate ON OFF in an erratic nature

    The holes in the deflector, allow the heat to be directed lower in the roast chamber and thats why one can see a steady ON OFF in the graph.
    I feel the thermostat comes on and off quicker because its reading real heat rise and fall from low down in the roast chamber not deflected heat

    KK

  12. #12
    Senior Member sidewayss's Avatar
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    I used to have a heat issue with my Cookwell turbo oven initially when i had the KKTO, meaning my roasts were taking over 20 minutes ( more like 24 minutes) due to the extension cable of over 10 metres. The roasts were nice but did not have a sparkle to it. Smooth, but uninteresting.

    Previous member AM assisted me to angle the blades from straight up and down (90 degrees) to 40degrees angle in order to distribute heat better without the heat guard.
    If the blades were not angled when the heat guard was removed, the halogen elements would have had a shortened life expectancy.

    Temperature reading with the DMM read 274 degrees in the empty chamber with the dial reading at 250 degrees.

    Roast times have been at 17-18 minutes after the mods. Beans look better. Tastes balanced with sweetness, origin character and acidity.

    Don, try it without the heatguard and bend your blades to about 45 degrees. Make sure you bend it in order for heat to go into the chamber, not back up. Look at how your blades are rotating and work it out from there.

    Pics available later.

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    Hi Sidewayss, Any chance of posting some pictures of the angled blades. I have cut holes in my heat guard similar to the ones in the photo KK posted, but would also like to adjust the angle of the blades, just not sure which way they should go.

  14. #14
    Coffee+carbon=heaven Mono's Avatar
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    Hi marke, sorry to butt in but following Sidewayss' advise I angled mine. Start your TO and watch which way the fan rotates then bend the trailing edge of the blades AWAY from the direction of rotation as this will direct the heated air downwards.
    Last edited by Mono; 4th July 2013 at 08:49 AM. Reason: TYPO

  15. #15
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    Thanks mono, I'll give it a go tonight and see how much difference it makes to my roasting
    Last edited by marke; 4th July 2013 at 09:24 AM. Reason: typo

  16. #16
    Senior Member sidewayss's Avatar
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    Thanks Mono for filling in while I was absent.

    Here's a pic as requested.

    The blades are easy to bend with a pair of pliers. 45 degree angle is the recommendation in order to draw the heat from the halogen elements into the chamber to improve the convection cycle.

    Certainly look at how the blades are rotating. You get a better idea of rotation once you turn it off and see the fan slow down.
    Again, angle the blades in order for the heat to draw down to the beans.

    As illustrated, the heat shield has been removed.

    Keep in mind any warranty for the oven will be void with any modifications.

    The modifications may have an effect on the silicon ring sitting on the lip of the pot, so keep an eye on any bubbling occuring.
    You may have to reduce the heat setting when roasting if you notice any problems.

    Keep us posted.
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  17. #17
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    Behmor Coffee Roaster
    I did a roast last night with the holes in the heat shield, but with out changing the angle of the fan blades. It knocked 3-4 min's off my 600g roast, and the roast was a lot more even. I noticed that the TO cycled a lot less as well. I may leave it at that and not bend the fan blades until I am ready for much larger roasts...

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