I learned my lesson after a couple of attempts. If this is on an
important part, I drop it off at a machine shop and pay a pro to do
it. Sounds like others may have had better luck.

On the welding group, several people have reported success welding a
washer to the end of the screw and then welding a nut to the washer.
Probably easier with larger bolts and may require more welding skill
than I have. I'll have to try it some day though.