Job shops continue to have foot operated resistance welders in use. They are fewer but they are out there. The operators foot actually provides the initiation and force of the weld with leverage multipliers built into the machine design. To replace the persons foot a force mechanism must be provided. It must be capable of providing the force needed for the application.
FOOT OPERATED ROCKER ARM WELDER
To spot weld 1 mm (0.040 in) or 3 mm (0.120 in) steel a force of 3 Kn (700 lb) to 4.5 Kn (1000 lb) approximately might be used. A pneumatic cylinder which could produce that strength through the mechanical advantages built into the machine would be necessary. Stroke length would also need to be considered. These and other considerations can be discussed with local area Resistance Welding Machine Suppliers or Distributors. They will know the proper sources for the parts and information to make this conversion a success.
Machine design is beyond the scope of this discussion.