Recent advances in spot-welding technology such as high frequency direct current (HFDC) inverter welders provide an improved and reproducible method to spot-weld difficult junctions. The importance of removing the oxide layers on metal surfaces, accurately delivering the weld pulse profile, and controlling the force applied to the materials during the welding process are discussed in the context of resistance spot-welding a molybdenum single crystal to a tantalum loop and attaching a tungsten-rhenium thermocouple to the crystal.