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First build failure..
jedovaty
Jack - good point on the other appliances, I did make sure of that the last few times. Fan wearing down is certainly a plausible theory, that could explain why the BT goes down without a very strong ET, as well as the more uneven roasts.

Would this also explain the inconsistent temps, where historically FC would occur between 392 and 400, and now all of a sudden it happens at 370 to 380? The only other explanation for this, I noticed my BT thermocouple has become quite a bit frayed, it's probably touching something metal. Hrrrm.
 
BenGeldreich
Jano,

Keep your head up!!! Coffee roasting isn't easy. I've failed more than I've succeeded. I've probably roasted 40 lbs of coffee and only 7 of the 40 were outstanding. 17.5 % success rate isn't something to write home about but the success out way the 33 lbs of mishaps or failed roasts.

I know you were tinkering with running a Variac and am not sure how you are powering your TO. Can you fill us in on your current electrical setup.

Ben
--------

Ben

Turbo Oven Roaster w/ Variac, TC4Cw/ Bourbon | Bezzera Strega | Baratza Vario Grinder | Yama 5 Cup Syphon | Aeropress
 
Lawnmowerman
Has anyone besides me noticed what appear to be internal heat leaks in a turbo oven between the element and thermostat sections? I have a 1200 watt flavor wave that shines light from the element up thru the holes that the elements themselves are mounted on into the thermostat area! This can cause serious temp swings i think, and i will be plugging these when i install a bypass switch. Still working the roaster.
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
Koffee Kosmo

Quote

Lawnmowerman wrote:
Has anyone besides me noticed what appear to be internal heat leaks in a turbo oven between the element and thermostat sections? I have a 1200 watt flavor wave that shines light from the element up thru the holes that the elements themselves are mounted on into the thermostat area! This can cause serious temp swings i think, and i will be plugging these when i install a bypass switch. Still working the roaster.


The design needs to be like this' as it draws in air for the fan to blow in to the chamber
If there is no expelling and the chamber is sealed it will create pressure and it will blow

Thats my take on it B)

KK
I home roast and I like it. Designer of the KKTO
Roaster Build information
https://homeroast...ad_id=1142

https://docs.goog...lide=id.i0
Blog - http://koffeekosm...gspot.com/

Bezzera Strega, Mazzer Robur Grinder, Pullman Tamper Convex,
(KKTO) Turbo Oven Home Roaster.
 
Lawnmowerman
Air is drawn into the top section of the co thru a cencentric vent. And there is a vent on top. I thought co systems use forced air. What i am seeing appears to be a design flaw. The plate that the element mounts to has 3 die cut holes in it to accept clips that hold the element. These appear to be causing heat leaks out of the r c area.
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
BenGeldreich

Quote

Lawnmowerman wrote:
Has anyone besides me noticed what appear to be internal heat leaks in a turbo oven between the element and thermostat sections? I have a 1200 watt flavor wave that shines light from the element up thru the holes that the elements themselves are mounted on into the thermostat area! This can cause serious temp swings i think, and i will be plugging these when i install a bypass switch. Still working the roaster.


Does the flavor wave model use a light tube as a heating element? If so they have more than one design flaw! I could never get an even roast with my flavorwave it had hot spots and air wasn't flowing in a conventional manner. If you get a chance pick up a Galloping Gourmet or a model that doesn't use a light bulb as a heat source. You will notice the difference just by Turing the fan on.

Look forward to seeing the roaster!!
--------

Ben

Turbo Oven Roaster w/ Variac, TC4Cw/ Bourbon | Bezzera Strega | Baratza Vario Grinder | Yama 5 Cup Syphon | Aeropress
 
jedovaty

Quote

BenGeldreich wrote:
I know you were tinkering with running a Variac and am not sure how you are powering your TO. Can you fill us in on your current electrical setup.


Ben, here's what it looks like:

AC -> TO's fan
AC -> HF Router Speed Control
HF Router Speed Control -> TO's heating element
AC -> LCD power brick
LCD Power brick -> 12V motor
LCD Power brick -> 12V-5V car cigarette cell phone power adapter
CCCPPA -> arduino

AC comes from a 20A circuit, and all appliances are off. I measure draw of all items at max through a heavy duty power strip, and it was something like 12-13A. No extension cords used. All power cables support 15A.

I'm really confused -- I was absolutely convinced last week the fan in the TO is to blame, but studying the past graphs, I'm not convinced as the ET continues to behave normally. My ET probe (***) sits just above the beans. The fact that ET is fine rules out the HF RSC item.

Regardless, going to take apart the TO in a couple weeks and see if it needs a cleaning. If I don't find anything out of the ordinary, will try another roast, and if that fails, I'm going to junk the project and find something commercial. I just don't feel like tinkering with this stuff any longer.

jano

*** -- ET Probe.. hahahahahhaha Grin
Edited by jedovaty on 03/15/2012 11:10 AM
 
Lawnmowerman
Please dont junk your project. A lot of people are drooling over all that stainless steel. At least let us know if you do so someone can retrieve it. Have you even considered hgbm? Been using mine for almost a year and very pleased with it. You coulduse a heat gun with your roaster with a different lid.
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
jedovaty
Few new developments. Inspected my deni TO and can't tell if the fan is performing accurately without taking it apart. I did manage to use the kkto to evenly roast some organic almonds which were then pulverized into a most excellent butter, but that's for another forum.

The past weekend I found an ad for one of the old 1470W galloping gourmets which I subsequently posted. Have to say, my first "weird" experience on craig's list. The guy was unbelievably desperate to sell the item, lied on multiple occasions, but fortunately, the thing works (albeit is gross and needs a major cleaning). He waited over an hour for me in a rainy parking, so I didn't have the heart to talk him down any lower than $20.

Soon as I have some time, going to sanitize and modify the GG and give this a second go-round. Until then, kean and portola will have to do.

Now to decide whether to go the SSR route or variac. The SSR is appealing as I'll be able to log in pCataui, however, I don't like the idea of having extra cables (one will have to connect the oven to the arduino). And the variac, well that thing's just a big ol' monster.

I will also need to find a better way to get the bean temp, I think the frayed TC was causing some issues if pushed up against the colander.
 
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