That is not quite what I said, or at least not what I intended to advise. Modified appropriate MOT's are regularly used for making spot welders. I have even made one. My recommendation was based on whether the OP should try to wind the primary too. That is usually connected to mains and presents the usual risks plus some,if it is not done right. If the OP were going from 220 V to 110 V without changing the primary, I would be far less worried. In fact, I ran my 110V MOT spot welder from a Variac. I also included a zero crossing timer to limit the weld time to just several cycles of the supply line frequency (60 Hz).
John