"Terry Coombs" wrote in message news
Had another chat with the glass bead maker that wants me to fabricate
some tooling . She needs some mandrels made that are a piece of tungsten
rod welded/brazed to a stainless steel handle . The join is not subject
to the full heat of molten glass . Am I right in assuming that a TIG
torch set on DCEN will melt and fuse these two metals without filler ?
What filler is recommended ? I have on hand 308 309/309l , and some 312
in various sizes . I also have some ER70S2 on hand and some Invar42
nickel/iron filler . She indicates that these must be pretty straight ,
no wobbles when they are spun or rolled across a flat surface . I'm
thinking a long vee block with a cutout in the middle , maybe a spring
on one end to keep things pushed together . We're getting into uncharted
territory here for me , I'm open to suggestions - that pertain to the
task at hand , please .


I am sure you already considered silvalloy silver brazing, but silvalloy
(expensive) is stronger than your regular plumbing solder and has a higher
melting point. (around 1600 F I think) Having said that I kind of liked
the idea of a press fit, and maybe even a mandrel fit in case differential
heat expansion doesn't allow for a press fit to workwell enough. Drill,
thread, and taper the end of a rod to hold the insert. Slide a threaded
closer up over the other end to clamp down on the insert. If they drop it
and break the insert it may be replaceable if heat cycling hasn't frozen the
threads.