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Homeroasters.org » BUILDING A ROASTER » Turbo Oven Roasters
Who is here? 1 guest(s)
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Nothing about profiles...
renatoa
Searched this subforum about roasting profiling and the results found were been scarce.
Really, nothing else than "preheat, charge, then turn full power until first crack..." ?!
Is this the definitive answer to the perfect natural curve embedded in the machine ?
Those who fitted a variac or even using the embedded thermostat to control temperature, can you tell us more how are you controlling your roasting evolution ?
What change between naturals and washed?

Because I am using this oven with a drum, not being comfortable the horizontal agitation pan approach, I thought that this roasting method is very close to Gene roaster as heating principle, beans agitation, and air circulation, so borrowed some well tried routines from Gene user, like: preheat at 175C, charge, keep at 175C for 4 minutes, turn maximum (which for Gene is 245C), keep there until FC, lower to 238C, keep the desired development 1-2-3 minutes, drop.
Using this routine, I get FC at about 11 minutes for 500 grams, 12-13 minutes for 650 grams.
Tried also a 10 degrees per minute ramp from 175C to 245C, instead full turning full power, but no visible or taste differences.

What do you think about this process, worth trying significant profile changes, will the result in the cup surprise or we risk a batch of beans without reason ?
Again, what should change between naturals and washed for this machine type?

PS: forgot to specify that my oven has the diode mod in parallel on the thermostat ;)
DIY: TurboOven with drum, Popcorn
Moded commercial: Dieckmann RoestMeister, Nesco
PID/ramp/soak controllers
Grinder: mod'ed Porlex to 47 conical burrs
 
Koffee Kosmo
Jack H has a variac in his system with I believe a thermostat

I have found that the thing that can make the most noticeable difference is fan speed and will work in all design variants
I call it heat shear

Just remember that no 2 roasters work in exactly the same way, so what may work in your roaster may not work in another

KK
My web site > koffeekosmo.com.au I home roast and I like it :P
Blog - http://koffeekosm...gspot.com/
Bezzera Strega: BNZ MD74 Grinder: 5 Box hand grinders: Pullman Tamper Convex: (KKTO) Turbo Oven Home Roaster: CONA Glass Rod Syphon: Pyrex Brewer:
 
koffeekosmo.com.au
JackH
I removed the thermostat in my turbo oven and control the heating element with a Variac. No PID.

Preheat to 350F and dump the beans. Then raise the heater voltage (using the Variac) to maximum. Usually 10A read on my Kill-a-watt meter.

First Crack at about 9 minutes.

I use a TC4 connected to a laptop running RoastLogger to monitor both bean and environment temperature.

Monitoring the environment temperature and maintaining it no higher than 500F using the Variac, seems to reduce the temperature at the right time and let me control the roast at the end. My roasts are usually 12 to 13 minutes and I roast about 650g of beans.

I read some old study on roasting that says that environment temperatures greater than 500F and roasts longer that 15 minutes are not good. If I can find it, I will post a reference.

As KK said, turbo oven roasters can behave differently.....
Edited by JackH on 07/20/2017 03:14
---Jack

KKTO Roaster.
 
renatoa
The old study could be the Jim Schulman quote I based one of my other threads:
https://forum.hom...ad_id=5300

As you can see, some of his perfect roast requirements are checked in the turbo oven environment, whatever being the construction variation:
- start at 325F to 400F - checked
- no higher than 480F - checked

What is still debatable and open to experiments is the length of drying phase, and the evolution from 400F to 480F, ramp or jump full power.
From other sources I found that is not good to have more than 400F ET during drying phase, how this match with turning full power imediatelly after load ?

And, of course, naturals vs washed, really no difference in roast approach ?
Edited by renatoa on 07/20/2017 06:19
DIY: TurboOven with drum, Popcorn
Moded commercial: Dieckmann RoestMeister, Nesco
PID/ramp/soak controllers
Grinder: mod'ed Porlex to 47 conical burrs
 
JackH
renatoa wrote:

What is still debatable and open to experiments is the length of drying phase, and the evolution from 400F to 480F, ramp or jump full power.
From other sources I found that is not good to have more than 400F ET during drying phase, how this match with turning full power immediately after load ?

I think some of that is determined by the type of bean. Denser beans (like Africa) usually need more heat during drying and beans like Brazil (softer) need longer time with less heat.

In general, I just go full power and the time it takes to get to Max ET then I start reducing power


And, of course, naturals vs washed, really no difference in roast approach ?
I don't care much for the naturals so I don't roast them.


---Jack

KKTO Roaster.
 
allenb
renatoa stated:

As you can see, some of his perfect roast requirements are checked in the turbo oven environment, whatever being the construction variation:
- start at 325F to 400F - checked
- no higher than 480 F - checked


Many roasters that are capable of producing excellent coffee utilize ET temperatures well above 480 F.

If you look at Jim's statement below, he used the words "around 450 to 480F" and was not meaning it to be a not to exceed temperature.

Basically, this magic profile is a starting temperature of around 325F to 400F (163-204C), and a ramp up to around 450F to 480F(232-250C) in around 6 to 8 minutes, and holding it steady there to the end of the roast, whenever that may occur.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
renatoa
What about cracking the door... er, lid, in the FC stage, to calm down ROR?
Is there any "scientifical" evidence of the effect, and how long should keep open to obtain a desired raise?
Or is enough to keep ET fixed at a given value and no fresh air?
 
allenb
What about cracking the door... er, lid, in the FC stage, to calm down ROR?

If ones roaster isn't capable of a quick enough power level reduction and happens to have a "door" that can be cracked to reduce ET then this might be a good option.

Is there any "scientifical" evidence of the effect, and how long should keep open to obtain a desired raise?

I'm assuming you mean desired drop in RoR? This would be dependent on the roaster's thermodynamic properties and the amount of drop desired.

Or is enough to keep ET fixed at a given value and no fresh air?

Fixing ET at one set temperature throughout the roast would not be a good way to achieve a great roast.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
renatoa
Not fixing through the roast, but at the end...
In the final phase of FC, I see from most diagrams that ET is almost fixed, somewhere in a 240-260C range, so what should understand from this... ? :confused:

Something like this:
www.astounding.org.uk/ian/roaster/oven/roast01.png
 
bobbooks
I’ve studied scores of award winning profiles and there is a common thread. I’ve come to the conclusion that no batch of beans are the same, no grinder is the same, no water the same, roasting profile is not exactly the same every time, no brewing consistency and taste buds are not the same every day. Too many variables besides the roasting profile you’re trying to duplicate.

So just like my washing machine, dryer and dishwasher that have many different cycle options, I always use “normal” when using them. Same for roasting coffee. I use the same profile for all beans ( http://www.bobboo...et/ROR.htm ).

I know that the experts will disagree, but I think most are fooling themselves that every bean needs a different profile to get excellent results. I do understand that you need to have good beans to start with.

After roasting several years and having several people doing blind cupping for me many many times, I have found that the same roasted batch will give different cupping results, depending on the person, barometric pressure, weather, moon cycle, local baseball score and sun spot activity. The only thing I vary with the roast is the development time to get different roasts from light to city++.

90% of my roasts are pulled at just the beginning of second crack. I always have excellent results from all who get and taste my coffee.
 
renatoa
I heard the same from respected roasters, who are using same profile for years, for any beans, so there should be some truth inside... that the profiles are overrated.

I assume the table you linked means BT, right?
How do you measure BT in your (supposedly) turbo oven roaster ? Where is placed the probe ?
DIY: TurboOven with drum, Popcorn
Moded commercial: Dieckmann RoestMeister, Nesco
PID/ramp/soak controllers
Grinder: mod'ed Porlex to 47 conical burrs
 
JackH
Are we still talking about Turbo oven roasters? Or all roaster types?
---Jack

KKTO Roaster.
 
renatoa
This is what I want to hear too...

Though... BT evolution should be the same for any roaster type, ET is different depending how the heat is transferred.

For example if we remove the halogen protective tin in a turbo oven lid, the behavior change dramatical, convection become minoritar compared to IR radiation, and ET meaning became marginal in the final phase, when the brown beans eats a lot of heat from the halogen by direct radiation.
 
renatoa
Yep, seems that bobbooks is talking about turbo oven roasting, just go to the root page of this site to see the machine and article that ROR scale was he referring.
 
bobbooks
The thermocouple was mounted by drilling a small hole in the bottom of the Stir Crazy pan sticking up about 1/2 inch into the bean mass to measure the bean temperature.

See modifications on my SC/TO to roast 1+ pounds of beans at http://www.bobboo...

An additional modification was made by switching in and out a series diode with the Turbo heater. Either remove the thermostat and replace with a series switch and diode or put a diode across the thermostat and work the thermostat on the TO. I found that it is better to remove the thermostat because some of the TO thermostats start cycling before 500F.

Instead of turning the TO heater on and off to get the profile without the diode modification, I switch the diode in and out. This is usually done after the 1st crack to slow the ROR.

If the diode isn't used, and you switch the heater on and off without the diode, in my experience the heating element cools to quick, where as the diode in series simply slows it down.

Perfect roast profile every time.
 
renatoa
Or in parallel, as I wrote in OP, and in your other thread, this post:
https://forum.homeroasters.org/forum/viewthread.php?thread_id=5301&pid=63053#post_63025
 
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