Thermocouple welder/fixture
While not terribly safe, a welder for such thermocouples can be as simple
as a light bulb (to limit current), a carbon electrode, and a clip
to hold the twisted thermocouple wire just behind the weld.

And, an AC cord that plugs into the wall.   Like I said, not terribly safe.
We put the thermocouple wire into an insulated box, with the clamp holding
the stripped and twisted thermocouple wire end, and advanced the electrode until
it was nearly touching.   Plug in the AC, nudge the electrode (it will touch
the wire, start an arc, and the light bulb will light up).   When the bulb
is hot, and the wire melts and forms a bead, the arc will extinguish.
Unplug the AC before removing your thermocouple.







simulate this circuit &ndash; Schematic created using CircuitLab