A: No, you don’t use flux with a laser welder, but with some metals, you’ll get better welds if you use an inert gas shield, usually argon. And yes, they have vent fans that draw welding fumes out the back through a fine filter which traps the metallic fumes. The main danger is to your wallet, and occasionally annoying small burns to the fingers when you miss. They will sting, but don’t do major damage.

Note that welding platinum is the easiest, and 18K yellow gold is also easy. But lower karats of gold, or white golds, become increasingly trickier, and are more benefited by the use of argon shielding. Very high karat yellow gold, like 22K or 24K, is also difficult. Silver welds look better with argon, but it it’s necessary usually. However, silver is so reflective, and such a good heat conductor, that it takes considerably more energy to laser-weld than most other metals. If you’re doing lots of silver in heavier gauges of metal, you may need more than the lowest power lasers to get decent results in a reasonable amount of time. But for pieces that are mostly wire constructions, even the basic units should be fine.

Alpha Supply in Bremerton WA is a tools dealer who sells, among other things, new laser welders (I think mostly the current latest model CPP machines) to jewelry factories in India. They take back, in trade, the old units, which are usually Siro Alphalasers, either the ALS-35 or ALS-35S, or similar units. Depending on the degree of refurbishment needed to get them running, and which model (the ALS-35S is higher power) and its age, etc, they’ve been selling them here in the U.S. for prices between $13K and $17K or so. The Siro lasers are the same ones that B&D Sales sells, and also are the ones pictured in the Rio Grande tools catalog.

I don’t know how much the new versions differ from these older lasers, but it’s my impression that the design isn’t being modified a whole lot. They’re fairly simple, lacking lots of bells and whistles, but seem like reasonably sturdy lasers. They’re like used cars: don’t expect them to run like new, and some may need replacement parts sooner rather than later. These things are not like a rolling mill, which if cared for will last almost forever. They’re filled with high powered electronics. Power supplies can fail, optics can need replacement, computer control boards can go bad, and if you use it a lot, then expect to replace the flash lamp (for $400 to $600) yearly or near to it. But with that said, these lasers are of a generally well-accepted design that’s been working for a number of years, and are likely to work well for more years as well.