User made Thermocouple ideas and results

Gary V

TVWBB Fan
I decided to go this route because the thermocouples I was purchasing just seemed to have a shorter life than what I was expecting. After much thought and using products that I used in my last job, I decided to try my approach with a probe that works well for my grill. I purchased some solid wire, Kapton conductor insulated and outer jacketed Ktype thermocouple wire. My first probe was with the twisted welded tip and that came out fine. Only problem was that probe reacted way to fast. This was similar to the Thermoworks alligator clip style probe. My probe was slightly faster to respond, I believe, because it was solid conductor wire versus stranded. So to slow down I added a Kapton tape covering the tip. I believe that is used by others to make the tip less sensitive to air movement in grill. This worked better, but I still thought probe was too fast. So next thing I purchased was some 4mm x .6mm stainless tubing from Amazon. Cut tubing to about 1 1/4" long. Went to autoparts stores and got some JB Weld High Temp putty. Made a small batch up and started to pack the tubing a good half full with the stuff. Next cleaned up the thermocouple with 70% alcohol and re wrapped the tip with a little Kapton tape. Made a mark with sharpie to show how far the thermocouple will be pushed into the putty mix. Once done made sure both ends were packed well with putty and left it to cure overnight. Result was a much slower reacting thermocouple probe and it was very accurate. Only offset by -1 degree. Results were awesome. I compared this to an old clip to grate probe I had and it was slightly slower, but had a very smooth response. I liked the response more than my old clip style probe.

The Kapton wire is good to 750 degree F. This stuff is tough and if you do not expose it to flame, it works well. This stuff is used to validate sterilization furnaces which see 300 degree C temps. JB weld is good to 450 degrees F. 500 max. Last thing which was critical to the my results was placement of the thermocouple probe. I placed it slightly below the damper hole in the dome. I know some out there will think it needs to be closer to heat source, but on my grill, I have always had the best results with the probe up high in the ceramic grill. If you think the temp is too low, then place probe 1 and 2 where you think you need to control temp from and record results. If there is a big difference then adjust setpoint for pit probe accordingly.

Next cook will be ribs later in week so I will post results good or bad then.
 

WBegg

TVWBB Pro
I use a similar process to make my thermocouples, but I use a SS braided wire, and a jewelers welder to weld the tip. I also use SS tips I found on AliExpress (See link below). They are ideal because they have 1 closed end. Before inserting into tube, I wrap in a small piece of Kapton Tape to insulate from braid so it's isolated, and not grounded. I use a cement from Omega called Omegabond 600. It's a bit pricey, but 1 can will make 100s of thermocouples, and it's rated for 1400+ degrees F.

Thermocouple Tube
 
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