PUK2 Welding with fixtures and shims

OK, so I’m a “newbie” with a Puk2…

Project: tack welding tube bezels of uneven height to round 14ga
wires on an earring.

Question: If I use the welding table to set an earring down, can I
shim under the tube bezels to make them the same height in
relationship to the round wire that’s on the earring? A 2.5 or 2mm
tube bezel is shorter than a 3mm tube bezel, but I want them all to
sit at the same height above the wire. If I can shim- what material
should the shim be or does that matter as long as I only touch the
spot to weld. Is there a preferred shim stock to use (copper, brass,
stainless?) Will aluminum cause problems?

Other question: If an earring has two different fabricated bezel
heights, should I position the piece before welding with some kind of
fixturing device such as a third hand, or should I shim under the
shorter bezel while the piece is on the welding table like the tube
bezels mentioned above?

Ruthie Cohen

Project: tack welding tube bezels of uneven height to round 14ga
wires on an earring. 

Why not place the bezels top-down on the welding table for tacking,
thereby insuring that all the tops are at the same level?

Matthew Crawford
www.MatthewDesigns.com