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Homeroasters.org » BUILDING A ROASTER » Turbo Oven Roasters
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KKTO - My Humble Turbo Roaster
JackH
baysidedweller wrote:

I also use the Sunpentown oven, but the one I have uses far infrared nano carbon fiber heating element that responds very quickly. Also, like halogen, it glows orange red
There are 2 models: SO-2002 which is discontinued and the other one still in production is the SO-2007 and sunpentown's website: http://www.sunpentown.com/coov.html.


Thanks, I will look into the 2007 model. I am familiar with how slowly my oven responds and will have to learn the roast timing again for a faster one.

You can buy just the model 2007 turbo oven head from their parts section for $65.
---Jack

KKTO Roaster.
 
baysidedweller
Hi Jack,
You are right, Sunpentown sells only the head so you save money that way.
I also have quartz heating element for toaster ovens and when you compare the FIR nano to quartz, the nano element is even faster.
Sunpentown "claims FIR penetrates deeper, but I am not sure if that applies to coffee beans or not. But one thing for sure, the heat is almost instantaneous
 
baysidedweller
One more thing Jack,
I use Artisan for chart only and do not use their power control to pulse the heat. I used to use their slide but find the result a bit confusing. Instead, I bypass the slide and use a variac to control power, which is constant.
I do not know if that makes a difference in the difference between pulsing for conventional heating element versus nano fiber, but from my experience, I like the variac method better for my application. Could it be the software for the power slide is programmed for the metal heating elements?
Maybe you can experiment with it should you decide to buy the nano one.
 
JackH
I eliminated the original thermostat and use a variac wired to the heating element. Been running it this way for about three years now.

I did try PWM control using a solid state relay controlled by the TC4, but it did not seem to have the power level that the variac had, especially at maximum power.

I run everything manual and just use the TC4 for graphing the roast.
---Jack

KKTO Roaster.
 
Koffee Kosmo
Just posting a timber base KKTO that I build

KK
Koffee Kosmo attached the following images:
aedd03e4-bda6-4afb-894d-10a938935133.jpeg b2381dbb-24f3-4c13-81bb-10b29cd2bb5a.jpeg f8947068-ef16-4b61-8919-09cd8fb64b1a.jpeg

I home roast and I like it
Blog - http://koffeekosm...gspot.com/
Bezzera Strega: Mazzer Robur Grinder: 5 Box hand grinders: Pullman Tamper Convex: (KKTO) Turbo Oven Home Roaster: CONA Glass Rod Syphon: Pyrex Brewer:
 
http://koffeekosmo.com.au
Koffee Kosmo
Here are a couple of KKTO roasters built from my instructions by enthusiasts

One is built on a roast table and has a cooler next to it

KK
Koffee Kosmo attached the following images:
692d0feb-9ee7-4ed2-bf77-33d67f4a8e18.jpeg 53474493-22af-4916-9d34-d0e212c7c269.jpeg

I home roast and I like it
Blog - http://koffeekosm...gspot.com/
Bezzera Strega: Mazzer Robur Grinder: 5 Box hand grinders: Pullman Tamper Convex: (KKTO) Turbo Oven Home Roaster: CONA Glass Rod Syphon: Pyrex Brewer:
 
http://koffeekosmo.com.au
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renatoa
What was the reason to use a smaller diameter pot ?
Isn't the peripheral heat enough, volume reduction... ?
Isn't easier for the heat to penetrate 3 layers of beans, as I measured 500 grams in a 26 cm plate, instead 4-5 layers as in the 20-22 cm I saw in your design.
 
Koffee Kosmo
renatoa wrote:

1” What was the reason to use a smaller diameter pot ?
2” Isn't the peripheral heat enough, volume reduction... ?
3” Isn't easier for the heat to penetrate 3 layers of beans, as I measured 500 grams in a 26 cm plate, instead 4-5 layers as in the 20-22 cm I saw in your design.



1- Smaller inner pot is the roast chamber
The way it's constructed as a perforated chamber is to use the heat as it's forced from the top and reuse it as it bounces back
The other reason is to let chaff pass through and settle on the base thus making it a cleaner roast and less of a fire risk

2- No
The heat available from a TO is finite and it will struggle to roast coffee
So a volume reduction to the pot set is needed to allow the TO to work in its comfort zone with a little in reserve to do the job
Best volume is 7 to 9 lt of total roaster chamber

3- No
Beans share heat with each other as they roast ( do some research on endothermic reaction )
This closeness allows for greater heat retention in the bean mass while roasting and heat is not lost
So a well agitated larger mass is best

Heat temperature is king when roasting coffee
Every effort must be made to use every ounce of it and loose as little as possible

KK
I home roast and I like it
Blog - http://koffeekosm...gspot.com/
Bezzera Strega: Mazzer Robur Grinder: 5 Box hand grinders: Pullman Tamper Convex: (KKTO) Turbo Oven Home Roaster: CONA Glass Rod Syphon: Pyrex Brewer:
 
http://koffeekosmo.com.au
Wiz Kalita
Does this mean that the pasta pot version performs worse than with the suspended colander?
Also: Will a motor with 2 kgf/cm torque be strong enough?
 
renatoa
I am using a 4 kgf/cm 14W 60 RPM motor and no sign to be at the limit of its potential, when turning 600 grams of greens.

Which RC shape is best is still debatable, I am using now more IR than convection, so my interest is to have as few layers as possible, to allow all the beans be seen by the radiated heat.
 
Koffee Kosmo
Wiz Kalita wrote:

Does this mean that the pasta pot version performs worse than with the suspended colander?
Also: Will a motor with 2 kgf/cm torque be strong enough?


Both fitted or suspended colander / roast chambers work
The pasta pot version was developed because its easier to construct and this current design followed the suspended roast chamber version first released about 2008/9

Re Motor
Always use a motor that can handle the job by a factor of 2 or as close as possible

KK
I home roast and I like it
Blog - http://koffeekosm...gspot.com/
Bezzera Strega: Mazzer Robur Grinder: 5 Box hand grinders: Pullman Tamper Convex: (KKTO) Turbo Oven Home Roaster: CONA Glass Rod Syphon: Pyrex Brewer:
 
http://koffeekosmo.com.au
Wiz Kalita
Thank you for the information. I don't doubt that it roasts equally well, but does the chaff collection work? Since there isn't much of a gap on the sides.
 
renatoa
I see an issue for both roasting recipients: the lateral holes.
I would close them with alu/kapton tape, if existing, and let only the holes in the bottom.
This way a circular/toroidal airflow is forced through the bean mass, without lateral losses/dispersion.
 
Koffee Kosmo
Wiz Kalita wrote:

Thank you for the information. I don't doubt that it roasts equally well, but does the chaff collection work? Since there isn't much of a gap on the sides.


I have completed over 3 thousand roasts in my roaster
The chaff removal to the outer chamber is in the ball park of over 95% on both designs

https://koffeekos...ogspot.com

KK
I home roast and I like it
Blog - http://koffeekosm...gspot.com/
Bezzera Strega: Mazzer Robur Grinder: 5 Box hand grinders: Pullman Tamper Convex: (KKTO) Turbo Oven Home Roaster: CONA Glass Rod Syphon: Pyrex Brewer:
 
http://koffeekosmo.com.au
Koffee Kosmo
renatoa wrote:

I see an issue for both roasting recipients: the lateral holes.
I would close them with alu/kapton tape, if existing, and let only the holes in the bottom.
This way a circular/toroidal airflow is forced through the bean mass, without lateral losses/dispersion.


If this design was fully manufactured then this would be an option
Possibly as a limited number of slits on the sides and several on the base

Exit points on the sides are needed as the chaff in the initial crack stages tends to fly above the roast in a vortex looking for a way out
As the chaff becomes dryer and collides to become smaller in size it exits from the side holes that are exposed above the agitating beans

However most of the chaff exits from the bottom
But that is not due to air pressure force alone - it’s the grinding action and weight of the agitating beans with fan assistance that pushes the chaff down and out from the base holes, the Turbo Oven has a mild fan

KK
I home roast and I like it
Blog - http://koffeekosm...gspot.com/
Bezzera Strega: Mazzer Robur Grinder: 5 Box hand grinders: Pullman Tamper Convex: (KKTO) Turbo Oven Home Roaster: CONA Glass Rod Syphon: Pyrex Brewer:
 
http://koffeekosmo.com.au
renatoa
As I see in my machine, the whole acts somewhat is a giant cyclone.
Or as a reversed flow Stronghold S7.
The air (and chaff) is sucked in the middle, by the turbine, then, passing through blades a peripheral vortex is generated along the lid and then the walls, where the chaff descend spiraling, relative slowly, due to rotating air stream.
If chaff not captured somewhere along the outer pot bottom corners, to be evacuated, it will be sucked in the middle of the roasting pot, obscuring about 1/4 of central area, around the shaft.
Will come later with a video of the machine fitted with some strings, to see air stream direction in the critical points.
 
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