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1lb Fluidbed build, progress and photos
Erichimedes
Top  #26 Print Post
Posted on 10/17/2013 10:04 PM
I installed the thermocouple in the heater outlet of my roaster, with great results! It seemed to follow the temperature really well, and responded really quickly to changes I made. I'm psyched!

i51.photobucket.com/albums/f400/Weasel9/Roast.png
 
allenb
Top  #27 Print Post
Posted on 10/18/2013 8:50 AM

Quote

Erichimedes wrote:

I tried a BT probe in the bottom of the RC about 3/4" below the glass, with a 1/2" probe, and it didn't get very accurate readings. I compared it with a thermocouple dropped in the top right in the middle of the rolling bean mass, and it was about 60 deg F off at the end of the roast.

My guess at this point is to try a longer thermocouple probe? What has been others' experience with this?



You're making great progress on this build!

From experimenting with many fluidbeds over the years I've found only a couple of locations for BT that produce beneficial results and don't vary depending on where ET happens to be at a given moment.

One is a little above the static green level and no further than 1/4" in from the roast chamber outer wall (round RC). The other is also near the RC outer wall but much further up near the top of the RC but this one has only been useful with my Sirocco sample roaster and Freshroast.

I've found when placing the sensor lower into the bean mass that environment temperature has too much influence on the bean temperature sensor.

You mentioned needing to move the sensor further into the RC. There is a minimum distance on sensor length extending into the RC that won't allow skewed readings from conduction to the RC wall or RC exterior. I'm not sure what the minimum is but I would not go less than 1" for a typical bare thermocouple and for 1/8" dia. sheathed probes not less than 2".

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
oldgearhead
Top  #28 Print Post
Posted on 10/18/2013 8:59 AM
I started out in 2011 with two TC 'K' probes: a 0.50 inch located 1.5 inches blow the perf plate mounted through the sink drain tube, and a very long one (BMT) through the top and down into the bean mass. What I quickly learned was the BMT probe was very accurate (400?F at first crack), and the lower one would track the BMT -30?F. Also by adding restriction to the RC air outlet I could measure the process varible (PV) temperature of the business end of the RC (perf plate), without beans. So, when I decided to trap all the chaff in the RC, I quit using the BMT probe, and rely on:
__ET = Total roast time
__PV = Hot air temperature
__Sight
__Smell
__Sound
__Temperature (0.50 inch probe)

Recently I've been adjusting only the blower speed, during the roast and set the temperature based on the test weight of the green beans.
oldgearhead attached the following image:
tc-k6a.jpg
No oil on my beans...
 
Airhan
Top  #29 Print Post
Posted on 11/15/2013 11:57 PM
Did you ever end up painting/staining your wooden enclosure?
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
 
Erichimedes
Top  #30 Print Post
Posted on 11/16/2013 1:29 PM
Airhan, no! I've been meaning to, and actually right now is a good time for it too, since I'm waiting on a power supply for the Arduino/TC4. I'll probably get to it in the next couple weeks, and I'll post photos when it's done.

I've also finally made a hot air return pipe, so that will be installed, and I will be experimenting with recirc and posting the results here.
 
SmokNmirz
Top  #31 Print Post
Posted on 01/15/2014 6:45 AM
Erichimedes, any updates to this project?

What type of welder were you using in the livingroom??!!?

If I tried that my wife would keep bringing up the name of Bobbit...
L-1p, HG-1-motorized, Monolith Flat, (ordered) mini500Plus.

If whatever you do does not put a smile on your face then rethink what you are doing.
 
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