.. you may want to be sure the "material is firmly locked into the head
o-ring. (continued)
You have two options. (1) you could re-machine the o-rings to give them
a dovetail shape (the wall on each side will taper back toward the
bottom, i.e., the bottom of the grove should be wider than the top. Be
forewarned, most machine shops cry and bitch about doing this. However,
this is a common approach in the vacuum industry to hold rubber o-rings
and seals into removable parts. By pounding in the wire it will be
locked into and fill up the taper and, essentially, become an integral
part of the head. (2) I don't think you would hurt the head if you very
carefully TIG welded a tiny spot weld in few places. You would make a
small fusion weld (be sure to leave enough metal above the surface for
later clean-up) in three, or more places. The key is to keep the weld
puddle size so small that little heat is added to effect your -T6 heat
treatment. Of course, you could always re-heat-treat the heads but that
adds cost and may not be needed. Try to determine the alloy properties
of your head and then find a aluminum wire with properties that closely
resemble that. (CTE & compressive strength). Best of luck, -Elon
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