New Thermocouple Welding Process


 
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WBegg

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Hey Y'all,

I've recently been making my own thermocouples, and if you know the process, it requires welding together (for best results) the two wires that consist of different compositions of metal.

I was previously accomplishing this by using a car battery to arc the wires together. Not only was this dangerous, but it pretty much destroys the battery after a while.

I saw a video on YouTube of a cheapish jewelry pulse welder, and thought it might just work. I bought one, and WOW. It puts a perfect weld bead on the two wires for temp measurements! Here's a pic of the weld (sorry for the blur, I don't have a macro lens).

9VJqSAP.jpg


And here's the finished TC, which has a much better response than the "battery" versions I've made before.

a7zUTLu.jpg


As a giveback to the forum, and as a way to test for me, I'm giving away 3 TCs to the first 3 forum members that let me know through PM.

And here's the link to the welder I bought..... https://www.amazon.com/exec/obidos/ASIN/B00BWO9LTE/tvwb-20


Cheers
 
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that looks great! The TC you generously sent me in the past works really well, so if this is improved then even better!

Any chance of putting a food-grade SS tip on it?

Your K-type connectors are great quality too, do you have a good/cheap source for them?
 
Interesting. Looks an awful lot like a TIG torch without gas, and a small pulsed power supply. I wonder....
 
DavidNP said:
that looks great! The TC you generously sent me in the past works really well, so if this is improved then even better!

Any chance of putting a food-grade SS tip on it?
I bought in bu
Your K-type connectors are great quality too, do you have a good/cheap source for them?
Click to expand...

I bought the connectors last year in bulk from Auber Instruments. Got a good deal. I've been looking for SS food probe sleeves for a while now with no success. Still looking.

The connector I bought is this

It's made by Omega, great quality.
 
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That rig looks like the actual welder you're supposed to use for this process. Also Begg, I threw away your thermocouple a while ago (forgot to tell ya), not because it didn't read well, but after a 700 degree cook the spring in the alligator clip was toast.
 
SteveCK said:
That rig looks like the actual welder you're supposed to use for this process. Also Begg, I threw away your thermocouple a while ago (forgot to tell ya), not because it didn't read well, but after a 700 degree cook the spring in the alligator clip was toast.
Click to expand...

You goof. The clip is just a way to connect. Any Radio Shack clip would have sufficed for a replacement. Drrrrrr.

The TC is in a sleeve that slip fits into the A Clip.
 
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I understood that, but I had 4 others that worked properly and were already setup to attach to my pit - no need for me to waste time to fix it. Bottom line is that it worked just fine. Do you fill the sleeve with a thermal conductive epoxy? What do you use?
 
SteveCK said:
I understood that, but I had 4 others that worked properly and were already setup to attach to my pit - no need for me to waste time to fix it. Bottom line is that it worked just fine. Do you fill the sleeve with a thermal conductive epoxy? What do you use?
Click to expand...

I've tried a few things, but I settled on an adhesive made for gluing BBQ seals. it has a rating of 1200 degrees. I haven't been able to find in the states, so now just using JB Weld. It's only rated for 500 degrees, but should be good for smoking.

I'll do some searching to find the brand name of the epoxy (glue actually) I was using before.
 
DAP makes a fire rated silicone sealant, I think good to 1200*. Not sure if JB Weld or this DAP product is safe from off gassing into food though
 
I'm trying hard to convince myself that I don't need to tinker.... I may have to order some of that, and see if I can get my TIG welder to join that.

You need a electrical path from ground to electrode to weld that bead. Are you trimming back the inner insulation far enough to attach a ground close to the bead?
 
JKalchik said:
I'm trying hard to convince myself that I don't need to tinker.... I may have to order some of that, and see if I can get my TIG welder to join that.

You need a electrical path from ground to electrode to weld that bead. Are you trimming back the inner insulation far enough to attach a ground close to the bead?
Click to expand...

Yep, with insulated tweezers connected to ground.
 
It does seem like a tiny little bit of overkill to use a 240v TIG welder to be welding up 22ga thermocouples.....lessee.... put the torch in the vice, use the foot pedal control, dial it WAY down (think I can get down to 10A or some such.) No filler necessary. Have to see if I can get some good insulated alligator clamps, I've got some good 12ga wire I can use for a ground extension from the welder clamp. DC process, doubt that AC would be necessary (or desired, FTM.)

I'm not sure if I should offer you a beer, or kick you in the shins. :D

Edit: Ha! HEMOSTATS! Need to pick up a couple of these, and solder/weld on a 12ga ground conductor. That'd be awfully nice for handling the junction during welding. Planning using gloves anyway, I'm not too concerned about inserting myself on the ground path.
 
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JKalchik said:
It does seem like a tiny little bit of overkill to use a 240v TIG welder to be welding up 22ga thermocouples.....lessee.... put the torch in the vice, use the foot pedal control, dial it WAY down (think I can get down to 10A or some such.) No filler necessary. Have to see if I can get some good insulated alligator clamps, I've got some good 12ga wire I can use for a ground extension from the welder clamp. DC process, doubt that AC would be necessary (or desired, FTM.)

I'm not sure if I should offer you a beer, or kick you in the shins. :D

Edit: Ha! HEMOSTATS! Need to pick up a couple of these, and solder/weld on a 12ga ground conductor. That'd be awfully nice for handling the junction during welding. Planning using gloves anyway, I'm not too concerned about inserting myself on the ground path.
Click to expand...

No worries, I wear shin pads.

I've actually done this with a friends wire feed welder (just used the wire to act as an electrode) and it worked well. Very important to insulate. I've been popped a few times even with the Jewelry Welder.

Maybe I'll make a video of the setup in use.
 
And now I'm thinking about another way..... serrated ground in the vice (which would be grounded by the welder ground clamp,) might let me get away with a shorter "stick-out" on the thermocouple joint. More than one way to skin this critter.
 
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