Fix Thermocouple

[capwizard]

I have 3 thermocouples which I bought from Aliexpress has 2 meters long, very inconvenience to use. my question is thermocouple is two metal welded together. can I cut it then weld to make multi thermocouple?

I cut open the one is not working, the wires are separated can I weld it and fix it?

[sam_sam_sam]

Re: Fix Thermocouple

Does it work when you put them together if so then yes if you can welded if you can do it with out distorting the two wires

Or you can twist the two wires together and use a wire crimp and cut the end off of it

I have done this on “ K “ type before and work very well

[momaka]

Re: Fix Thermocouple

If it's type-K, yes you can fix it.

I've done it quite a few times, actually. But my procedure isn't very exact, so bare with me as I try to explain. Basically, the idea is to overload the thermocouple wires with current at a certain point of interest, which will then weld together.

The first thing to do for this procedure is you twist the two thermocouple wires at one end so that the twisted segment is about 5 to 10 mm long. Next, put an alligator clip on the twisted section closer to where the wires untwist and go into their insulating sleeves (i.e. DON'T put the alligator clip at the end of the twisted segment.) After this, you will need a high current supply... but something that won't go kaboom when you short-circuit it, because that's what we will be doing pretty much. That is, you take the other end of the alligator clip and connect it to your high current power supply's ground. After this, you bring the thermocouple's twisted end close to the positive (or negative?) end of the high current power supply and you short it out - i.e. you are putting a short-circuit / high current through the twisted segment of the thermocouple wire ONLY (and not the entire probe). The high current will melt the two twisted wires of the thermocouple and _hopefully_ weld them. I say "hopefully", because you have to get the current/voltage (i.e. dissipated power) right.

When I fixed my probes, I actually didn't have a high-current power supply. So what I used instead... and note, THIS IS DANGEROUS ... is a small space heater set to low (about 6 to 8 Amps power draw from the wall normally, IIRC) and essentially powered it through that short twisted thermocouple segment. Because the two wires of the thermocouple are not able to carry the current load that the space heater requires, they melt and fuse together. Of course, for some thermocouples I had to try the above procedure a few times, mainly because I was probably running way too much current through them. Thus, if your twisted segment keeps "blowing up" and not welding, you current is probably too high. And if the twisted segment only starts glowing barely, then you're not supplying enough current.

And again, just to clarify with the abovementioned method: you are NOT running current through the entire length of the thermocouple probe, but ONLY the short twisted section at the end you want to "weld" together.

Also, another thing to clarify with MY method with the space heater above above: I was working with LIVE WIRES here, which IS VERY DANGEROUS. DO NOT ATTEMPT if you don't fully understand the risks of doing that or what you are doing.

Oh, and wear safety glasses if "welding" the thermocouple with the above procedure. Like I said, if you put too much power, the twisted segment will spark and blow up and not weld.
So any time you have things like that, you should be wearing safety glasses. I mean, this should go without saying, but I've seen people do silly things without any care too many times... and you only have TWO eyes. So better to protect them.

[sam_sam_sam]

Re: Fix Thermocouple

If it's type-K, yes you can fix it.

I've done it quite a few times, actually. But my procedure isn't very exact, so bare with me as I try to explain. Basically, the idea is to overload the thermocouple wires with current at a certain point of interest, which will then weld together.

The first thing to do for this procedure is you twist the two thermocouple wires at one end so that the twisted segment is about 5 to 10 mm long. Next, put an alligator clip on the twisted section closer to where the wires untwist and go into their insulating sleeves (i.e. DON'T put the alligator clip at the end of the twisted segment.) After this, you will need a high current supply... but something that won't go kaboom when you short-circuit it, because that's what we will be doing pretty much. That is, you take the other end of the alligator clip and connect it to your high current power supply's ground. After this, you bring the thermocouple's twisted end close to the positive (or negative?) end of the high current power supply and you short it out - i.e. you are putting a short-circuit / high current through the twisted segment of the thermocouple wire ONLY (and not the entire probe). The high current will melt the two twisted wires of the thermocouple and _hopefully_ weld them. I say "hopefully", because you have to get the current/voltage (i.e. dissipated power) right.

When I fixed my probes, I actually didn't have a high-current power supply. So what I used instead... and note, THIS IS DANGEROUS ... is a small space heater set to low (about 6 to 8 Amps power draw from the wall normally, IIRC) and essentially powered it through that short twisted thermocouple segment. Because the two wires of the thermocouple are not able to carry the current load that the space heater requires, they melt and fuse together. Of course, for some thermocouples I had to try the above procedure a few times, mainly because I was probably running way too much current through them. Thus, if your twisted segment keeps "blowing up" and not welding, you current is probably too high. And if the twisted segment only starts glowing barely, then you're not supplying enough current.

And again, just to clarify with the abovementioned method: you are NOT running current through the entire length of the thermocouple probe, but ONLY the short twisted section at the end you want to "weld" together.

Also, another thing to clarify with MY method with the space heater above above: I was working with LIVE WIRES here, which IS VERY DANGEROUS. DO NOT ATTEMPT if you don't fully understand the risks of doing that or what you are doing.

Oh, and wear safety glasses if "welding" the thermocouple with the above procedure. Like I said, if you put too much power, the twisted segment will spark and blow up and not weld.
So any time you have things like that, you should be wearing safety glasses. I mean, this should go without saying, but I've seen people do silly things without any care too many times... and you only have TWO eyes. So better to protect them.

Thanks for sharing this I have not tried it this way before but I will keep this in mind for next time

[momaka]

Re: Fix Thermocouple

^ You're welcome, Sam!
Hope it works for you too.