Hi Thomas I always sweat solder on to the piece I’m putting the pin
backs on. I then hold the backs in place by gently placing third
hands on top of the pin components, not only to keep the piece from
moving, but also as a heat sink. You don’t want to put too much
pressure on them though (particularly the side w/swivel to hold pin
tip) otherwise you could cause it to collapse. Works for me, hope it
helps you.
Lisa in sunny Oregon: )
http://www.hawthornestudios.com