On Tue, 11 Sep 2007 12:52:56 -0500, Ignoramus26973
wrote:

On Tue, 11 Sep 2007 08:58:24 -0700, wrote:
I have a BUNCH of shafts that need to be welded (using tig) on the end
to secure an arm that is swaged onto the shaft. The weld will be
about .375 long, bonding the arm to the shaft. Directly behind the
arm, with about .250 clearance is a nylon bushing.... I don't want to
melt the bushing when welding. I have to weld a bunch of these... in
the hundreds. MIG welding puts too much of a bubble there, and the
tig looks OH soooo much nicer.

I do not think that there is any way to avoid damaging the bushing
that is .250 away from the weld.

i

Oh heck yes. Heat conduction in steel is not that fast. Immersing
the bushing works for sure, weld 'n dunk also works if you're quick
enough. I've TIG-welded to within 1/4" of paint without discoloring
or blistering it. It is important to block the heat-sensitive part
from radiant heat from the arc.