Welding tiny beads on a tinier wire ?

Hi,

Does anybody have an idea just how I could weld a metal bead on a metal wire ?

The wire has 0.25 mm in diameter, the bead is about 4 mg or 0.8 mm in diameter.

The challenge is to center the bead on the wire - if the bead is not exactly centered, it will fall down once I heat the wire.

Usually, the bead material will have a much lower melting point than the wire, so in theory, I can use some alumina plate to hold the wire in place whilst melting the bead on it. For some reason, the bead never centers.

Any ideas ?

Thanks !

Robert