Frankenturbo KKTO

[borat123]

Just finished a fun filled day of making some serious mods to the KKTO......

First up was to replace the simmer stat with full manual on/off control for the heating element. Requires a relay which I fitted inside the top section, in place of the simmerstat. Control is through a switch plumbed out the side of turbo oven.

Im hoping that it will significantly increase the max batch size of the roast.

Will post some pics and results of testing tomorrow....

Also fitting a variable speed control to the fan, and will see what impact speed has to the roast and max batch size.

[Bean_Bear]

Re: Frankenturbo KKTO

Hi Borat,

Ive put a relay in my TO as well, I use a PWM control to vary the power from 5% to 95% or on/off. I didnt remove the thermostat, but leave it set to 250C (I will probably readjust for about 300C or take it out completely). PWM period is about 6 seconds at the moment, mostly to allow for decent relay life. I will put an SSR in the cct. when Im happy with what Ive got.

From your post I am assuming that you’ve removed the thermostat from the circuit completely.
Looking forward to seeing how yours turns out.

BB

[Koffee_Kosmo]

Re: Frankenturbo KKTO

So its true that the KKTO is highly tweak-able :

I would be very interested in your test results so dont keep us waiting to long

There is nothing better than test roasting during Christmas
If the family get stroppy roast them some raw nuts to keep them on side

KK

[borat123]

Re: Frankenturbo KKTO

Update:

Variable fan speed doesnt work with a standard dimmer switch....

[Bean_Bear]

Re: Frankenturbo KKTO

Variable fan speed doesnt work with a standard dimmer switch....

Generally these are shaded pole motors (a 240V AC induction motor), you need to use a fan speed control or “universal” control.

Poppers tend to use a DC motor which can be controlled by a light dimmer.

BB

[borat123]

Re: Frankenturbo KKTO

Generally these are shaded pole motors (a 240V AC induction motor), you need to use a fan speed control or “universal” control.

Poppers tend to use a DC motor which can be controlled by a light dimmer.

Hi BB, yes I read that full speed control with shaded pole motors is not really possible, but Im only looking for the ability to reduce speed by say 50%.

Apparently, low wattage light dimmer switches should work.... Im going to buy one and give it a try.

[borat123]

Re: Frankenturbo KKTO

1.2kgs Yirgacheffe....................................... .  

This is the largest roast Ive ever done in the KKTO.    I actually tried 1.5kgs, which Ive no doubt with the switching mod is doable, but was a little too much for the agitator motor.

Anyway,  1.2kgs was a breeze.    Have to rethink my combo vac/cooler system now though, as the larger batch overheats the vac motor when cooling.  

Heres some pics.  Apologies for the quality, taken with an iphone.  The dig camera battery was flat....

The profile.  MUCH easier to roast at the larger batch.  Just set (Eg element on) and forget until approaching 1C.


Hows this for a full pot  


Frankenturbo after brain surgery....  The relay is mounted where the timer switch used to be.   Thats a light dimmer in place of the temp dial.


Element switch.    Probably better positioned off the side somewhere.

[rival81]

Re: Frankenturbo KKTO

Thanks for sharing your graph & pics.

I dont own a KKTO but am curious as to the longer roast time, and the slow increase in temp, assuming each line is 1 minute of time? Is this normal for a KKTO roast or because of the large roast size, or just how you prefer to roast it?

Would doing a smaller batch and pre-heating to around 190 degrees allow you to reach first crack more around the 11 min mark, rather than at 22mins?

cheers

[borat123]

Re: Frankenturbo KKTO

Hi rival.

Rest assured theres absolutely no baking going on there.... :P
The pre-heat or thaw I use is at about 50c, for approx 5mins, just to even out the temp and moisture content through the beans. With bigger batches I find it gives me a more even roast and no issues with tipping.

With smaller roast sizes, a much steeper ramp is possible, but with most beans Ive found the slower ramp actually improves the taste, particularly at lighter roasts.

Ive found that with long gentle roasts, the KKTO seems to work exceptionally well at bringing out flavours that are otherwise not there if the ramp is too quick.

For my taste, the only thing Id change might be to pull it a bit lighter, say just on 2C, rather then sometime after (as per the profile above).

[Dimal]

Re: Frankenturbo KKTO

Awesome Borat.... [smiley=thumbsup.gif] 8-)

Mal.

[A_M]

Re: Frankenturbo KKTO

Generally these are shaded pole motors (a 240V AC induction motor), you need to use a fan speed control or “universal” control.

Poppers tend to use a DC motor which can be controlled by a light dimmer.

Hi BB,  yes I read that full speed control with shaded pole motors is not really possible,  but Im only looking for the ability to reduce speed by say 50%.    

Apparently, low wattage light dimmer switches should work....   Im going to buy one and give it a try.

Care to provide a little more info as to your mod and how you manage the roast profile ?

[borat123]

Re: Frankenturbo KKTO

Care to provide a little more info as to your mod and how you manage the roast profile ?

Hi AM,

The simmerstat removal / relay for an on/off switch mod was such a success I never got around to trying the low wattage light dimmer.   It would still be nice to vary the fan speed down though, say when the element is switched off.   I found a low wattage dimmer switch at Ikea, so might try that when I get some time one day.

The relay was just $10, 30A from Jaycar, and the switch is the same as the agitator motor switch for the KKTO. The power for the relay was from an old power pack I had spare. Once the timer is removed it fits nicely on the underside of the base of where the timer was fitted. Once the simmerstat is removed I covered the hole with some tin and permatex to keep the heat out.

I had an uncle who is an electrician drop by who helped with the 240V stuff. He also provided some of those right angle fittings to clamp on the end of the cables that now power the element directly.

For larger roasts (say 800gms plus) I switch the element on and leave it on until about 180C.   If any reduction of ramp is required up to then, I just burp the KKTO occassionaly.

Once beyond about 180, I use a combination of switching the element and burping.    I try to burp more than switch, as its easier and more predictable.

With roasts around 1kg, the bigger bean mass seems to make it even easier.  I just switch the element on and leave it right up to 1C, no fiddling required.

I found the real benefit of the mod has been the ability to do much bigger roast sizes without a big reduction in the temp ramp. 

Up at around 1.2kgs, I reckon the motor is now the limiting factor rather than the heat input.

And the larger roasts killed my vac / cooler system 

[Bean_Bear]

Re: Frankenturbo KKTO

And the larger roasts killed my vac / cooler system

Bugger, time for a fan in a bucket, big fan big bucket by the sounds of things.

I saw some 30cm prospecting screens on special at Anaconda (Mile End) on the weekend, nearly bought them, might be a good start for a new cooler for you.

[borat123]

Re: Frankenturbo KKTO

I saw some 30cm prospecting screens on special at Anaconda (Mile End) on the weekend, nearly bought them, might be a good start for a new cooler for you.

Thanks, Ill check it out...