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Thermocouple placement and protection
DavidG
I spent several minutes scouring our forum to see if there was already a general thread on this. So, Super Admins, please move this around to a more appropriate place, if there is one.

I spent several trips to big box hobby and home improvement stores trying to find thin enough metal tubing to help place/protect thermocouple wire tips. I haven't tried plumbing supply houses yet, but that is next, if the below idea doesn't last.

I welcome your collective experience and suggestions.

As a make-shift make-do, this is what I've done:

1. Went to a chain office supply store. Bought a pack of ballpoint pen refills (the fancy metal kind -- emphasis on metal) for $3.

2. At home, gently pulled the tips off and gently blew out the bulk of the ink onto paper towel. Avoided any ink on teeth or mouth (bonus); forgot to wear gloves (blue fingers).

3. In a shallow plastic tray, poured a bath of rubbing alcohol. Submerged ink refill tubes in alcohol for a while as a solvent for the remaining ink. Gently blew thinned ink out. Repeated soak and gentle blowing.

4. Added pipe cleaner to alcohol bath. Ran soaked pipe cleaners through pen tubes until mostly clean. (At this point, the bath was blue alcohol and my hands were blue, too)

5. Dried and cleaned everything, and then did a final clean soak in a new alcohol bath with a clean set of pipe cleaners.

So, the TC wires fit perfectly without pinching etc. The pen tubes fit in the existing thermo holes drilled in my poppers and Bmakers. And, the pen tubes are rigid enough to hand the beans flying around and getting knocked around during dumping, stirring, etc.... for now.

It's just quite a few steps, just to have 2 clean pen tubes. If these turn out to be not a long term solution, then I'm back to the drawing board.

I've heard of steam wands being used, and 1/32" copper tube. What else are you using out there in your roasters?

DavidG
europiccola | yama + coryrod | chemex | AP | clever
wbp1 | wepp1 | bm/hg | co hybrid (still coming soon...)
bvwelch
Hi David,

This a great topic, thanks for getting us started!

I'm mostly using hobby brass tubing with the cheap 'bead-type' TCs. But it isn't entirely satisfactory. I find I still have to expose the bead else the readings are way too low. -bill
Edited by bvwelch on 04/02/2010 7:18 AM
seedlings
Love the innovation, David! Besides fit, does the temperature seem to measure accurate?

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
DavidG
CHAD, good question. So far, so good. I am careful to make sure the nib of the TC wire and junction are protruding just a wee bit beyond the end of the pen tube. A side benefit is that the plastic end cap on the pen can be snipped and slid down the shaft to create a collar, of sorts, so you can adjust the placement of the tube. I'll try to post a snapshot later.

DavidG

Here http://www.staple...rea=SEARCH is the pen refill example. In store, they were 2 for $3.
Edited by DavidG on 04/02/2010 9:06 AM
europiccola | yama + coryrod | chemex | AP | clever
wbp1 | wepp1 | bm/hg | co hybrid (still coming soon...)
nufsaid
just go on ebay and you can get great thermocouples with SS braid covered wire and ceramic lined SS probe all for around 5 bucks and free shipping. I sware by them and use them for ambient and bean mass. Gerry
seedlings

Quote

gerry wrote:
just go on ebay and you can get great thermocouples with SS braid covered wire and ceramic lined SS probe all for around 5 bucks and free shipping. I sware by them and use them for ambient and bean mass. Gerry


Plug them into... a multimeter?

CHAD
Roaster: CoffeeAir II 2# DIY air roaster
Grinder: Vintage Grindmaster 500
Brewers: Vintage Cory DCU DCL, Aeropress, Press, Osaka Titanium pourover
DavidG
OK, progress report:

http://www.facebo...1526104909

Ball point pen tubes are working well so far. They handle being bean-battered with no problems and do not bend out of shape.

Con: if there is one, it's that the thermocouple wires slide a bit inside the tube. So, I adjusted and added some tape at the back end of the tube.

Pro: Unexpected benefit! Threaded plastic sleeve comes in REALLY handy. It acts as a slideable stop, but EVEN BETTER, if the hole in your roaster is the right diameter, it simply screws in place holding the thermocouple snug!

Here is a photo:
http://www.facebo...1526104909

And: http://www.facebo...1526104909


DavidG

... strugglin' to get photos from facebook to show... maybe I just need to paste them in the old way.
Edited by seedlings on 04/12/2010 7:55 AM
europiccola | yama + coryrod | chemex | AP | clever
wbp1 | wepp1 | bm/hg | co hybrid (still coming soon...)
DavidG

Quote

DavidG wrote:
OK, progress report:



Ball point pen tubes are working well so far. They handle being bean-battered with no problems and do not bend out of shape.

Con: if there is one, it's that the thermocouple wires slide a bit inside the tube. So, I adjusted and added some tape at the back end of the tube.

Pro: Unexpected benefit! Threaded plastic sleeve comes in REALLY handy. It acts as a slideable stop, but EVEN BETTER, if the hole in your roaster is the right diameter, it simply screws in place holding the thermocouple snug!

Here is a photo:
[img]http://www.facebook.com/photo.php?pid=2585671&l=93855b838b&id=1526104909[/img]

And: [img]http://www.facebook.com/photo.php?pid=2585688&l=16424ff94d&id=1526104909[/img]


DavidG

... strugglin' to get photos from facebook to show... maybe I just need to paste them in the old way.
DavidG attached the following image:
23684_1395775944195_1526104909_2585671_6171430_n.jpg

europiccola | yama + coryrod | chemex | AP | clever
wbp1 | wepp1 | bm/hg | co hybrid (still coming soon...)
DavidG
photo 2
DavidG attached the following image:
23684_1395776504209_1526104909_2585683_6196551_n.jpg

europiccola | yama + coryrod | chemex | AP | clever
wbp1 | wepp1 | bm/hg | co hybrid (still coming soon...)
DavidG
photo 3
DavidG attached the following image:
23684_1395776904219_1526104909_2585688_4499711_n.jpg

europiccola | yama + coryrod | chemex | AP | clever
wbp1 | wepp1 | bm/hg | co hybrid (still coming soon...)
jsutton
David:
If you only needed one for your app, I'll buy the second!
Jim
jsutton
Gerry:

if you find or see a "just go on ebay and you can get great thermocouples with SS braid covered wire and ceramic lined SS probe all for around 5 bucks and free shipping. I sware by them and use them for ambient and bean mass. Gerry"

that operate in the right temperature range for roasting, for $5.00 please email me. I can't find them.

There are loads of cheap ones listed whose max temp is ~300dF which is not useful.
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